GOBOARD6

index · ← GOBOARD5 · GOBOARD7 →
:: On the Geometry of a Go-board
::  by Andrzej Trybulec
::
:: Received July 9, 1995
:: Copyright (c) 1995-2026 Association of Mizar Users
::           (Stowarzyszenie Uzytkownikow Mizara, Bialystok, Poland).
:: This code can be distributed under the GNU General Public Licence
:: version 3.0 or later, or the Creative Commons Attribution-ShareAlike
:: License version 3.0 or later, subject to the binding interpretation
:: detailed in file COPYING.interpretation.
:: See COPYING.GPL and COPYING.CC-BY-SA for the full text of these
:: licenses, or see http://www.gnu.org/licenses/gpl.html and
:: http://creativecommons.org/licenses/by-sa/3.0/.

environ

 vocabularies NUMBERS, SUBSET_1, REAL_1, PRE_TOPC, EUCLID, GOBOARD1, ARYTM_3,
      MCART_1, ARYTM_1, RELAT_1, XBOOLE_0, METRIC_1, XXREAL_0, CARD_1,
      PCOMPS_1, RCOMP_1, STRUCT_0, CONNSP_2, TOPS_1, TARSKI, SQUARE_1, FUNCT_1,
      FINSEQ_1, TREES_1, GOBOARD5, COMPLEX1, RLTOPSP1, SUPINF_2, NAT_1;
 notations TARSKI, XBOOLE_0, ORDINAL1, SUBSET_1, NUMBERS, XXREAL_0, XREAL_0,
      XCMPLX_0, COMPLEX1, REAL_1, NAT_1, SQUARE_1, NAT_D, BINOP_1, FINSEQ_1,
      MATRIX_0, STRUCT_0, METRIC_1, PRE_TOPC, TOPS_1, CONNSP_2, PCOMPS_1,
      RLVECT_1, RLTOPSP1, EUCLID, GOBOARD1, GOBOARD5;
 constructors REAL_1, SQUARE_1, NAT_1, COMPLEX1, NAT_D, TOPS_1, CONNSP_2,
      PCOMPS_1, GOBOARD1, GOBOARD5, FUNCSDOM, BINOP_2;
 registrations RELSET_1, XXREAL_0, XREAL_0, STRUCT_0, METRIC_1, PCOMPS_1,
      EUCLID, TOPS_1, PRE_TOPC, SQUARE_1, ORDINAL1;
 requirements REAL, NUMERALS, SUBSET, ARITHM;
 definitions TARSKI, XBOOLE_0;
 equalities EUCLID, SQUARE_1, XCMPLX_0, RLTOPSP1, RLVECT_1;
 expansions TARSKI;
 theorems GOBOARD5, TOPS_1, SPPOL_2, TOPMETR, METRIC_1, PCOMPS_1, PRE_TOPC,
      EUCLID, TOPREAL3, SQUARE_1, ABSVALUE, TARSKI, TOPREAL1, NAT_1, XBOOLE_0,
      XBOOLE_1, XCMPLX_1, COMPLEX1, XREAL_1, CONNSP_2, XXREAL_0, RLTOPSP1,
      MATRIX_0, RLVECT_1;

begin

reserve n for Nat,
  i,j for Nat,
  r,s,r1,s1,r2,s2,r9,s9 for Real,
  p,q for Point of TOP-REAL 2,
  G for Go-board,
  x,y for set,
  v for Point of Euclid 2;

Lm1: (p+q)`1 = p`1+q`1 & (p+q)`2 = p`2+q`2
proof
  p + q = |[ p`1 + q`1, p`2 + q`2]| by EUCLID:55;
  hence thesis by EUCLID:52;
end;

Lm2: (p-q)`1 = p`1-q`1 & (p-q)`2 = p`2-q`2
proof
  p - q = |[ p`1 - q`1, p`2 - q`2]| by EUCLID:61;
  hence thesis by EUCLID:52;
end;

Lm3: (r*p)`1 = r*(p`1) & (r*p)`2 = r*(p`2)
proof
  r*p = |[ r*p`1 ,r*p`2 ]| by EUCLID:57;
  hence thesis by EUCLID:52;
end;

theorem Th1:
  for M being non empty Reflexive MetrStruct, u being Point of M, r
  being Real holds r > 0 implies u in Ball(u,r)
proof
  let M be non empty Reflexive MetrStruct, u be Point of M, r be Real;
A1: Ball(u,r) = {q where q is Point of M:dist(u,q)<r} & dist(u,u) = 0 by
METRIC_1:1,17;
  assume r > 0;
  hence thesis by A1;
end;

Lm4: for M being MetrSpace, B being Subset of TopSpaceMetr(M),r being Real
, u being Point of M st B = Ball(u,r) holds B is open
proof
  let M be MetrSpace, B be Subset of TopSpaceMetr(M), r be Real, u be
  Point of M;
A1: TopSpaceMetr M = TopStruct (#the carrier of M,Family_open_set M#) & Ball
  (u,r ) in Family_open_set M by PCOMPS_1:29,def 5;
  assume B = Ball(u,r);
  hence thesis by A1,PRE_TOPC:def 2;
end;

theorem Th2:
  for p being Point of Euclid n, q being Point of TOP-REAL n, r
  being Real st p = q & r > 0 holds Ball (p, r) is a_neighborhood of q
proof
  let p be Point of Euclid n, q be Point of TOP-REAL n, r be Real;
  reconsider A = Ball (p, r) as Subset of TOP-REAL n by TOPREAL3:8;
A1: the TopStruct of TOP-REAL n = TopSpaceMetr Euclid n by EUCLID:def 8;
  then reconsider AA = A as Subset of TopSpaceMetr Euclid n;
  AA is open by TOPMETR:14;
  then
A2: A is open by A1,PRE_TOPC:30;
  assume p = q & r > 0;
  hence thesis by A2,Th1,CONNSP_2:3;
end;

theorem Th3:
  for B being Subset of TOP-REAL n, u being Point of Euclid n st B
  = Ball(u,r) holds B is open
proof
  let B be Subset of TOP-REAL n, u be Point of Euclid n;
A1: the TopStruct of TOP-REAL n = TopSpaceMetr Euclid n by EUCLID:def 8;
  then reconsider BB = B as Subset of TopSpaceMetr Euclid n;
  assume B = Ball(u,r);
  then BB is open by Lm4;
  hence thesis by A1,PRE_TOPC:30;
end;

theorem Th4:
  for M being non empty MetrSpace, u being Point of M, P being
Subset of TopSpaceMetr(M) holds u in Int P iff ex r being Real st r > 0
  & Ball(u,r) c= P
proof
  let M be non empty MetrSpace, u be Point of M, P be Subset of TopSpaceMetr(M
  );
  hereby
    assume u in Int P;
    then consider r be Real such that
A1: r > 0 and
A2: Ball(u,r) c= Int P by TOPMETR:15;
    take r;
    thus r > 0 by A1;
    Int P c= P by TOPS_1:16;
    hence Ball(u,r) c= P by A2;
  end;
  given r being Real such that
A3: r > 0 and
A4: Ball(u,r) c= P;
  TopSpaceMetr M = TopStruct (#the carrier of M,Family_open_set M#) by
PCOMPS_1:def 5;
  then reconsider B = Ball(u,r) as Subset of TopSpaceMetr(M);
A5: B is open by Lm4;
  u in Ball(u,r) by A3,Th1;
  hence thesis by A4,A5,TOPS_1:22;
end;

Lm5: for T being TopSpace, A being Subset of T, B being Subset of the
TopStruct of T st A = B holds Int A = Int B
proof
  let T be TopSpace, A be Subset of T, B be Subset of the TopStruct of T such
  that
A1: A = B;
  reconsider AA = Int A as Subset of the TopStruct of T;
  AA is open by PRE_TOPC:30;
  hence Int A c= Int B by A1,TOPS_1:16,24;
  reconsider BB = Int B as Subset of T;
  BB is open by PRE_TOPC:30;
  hence Int B c= Int A by A1,TOPS_1:16,24;
end;

theorem Th5:
  for u being Point of Euclid n, P being Subset of TOP-REAL n holds
  u in Int P iff ex r being Real st r > 0 & Ball(u,r) c= P
proof
  let u be Point of Euclid n, P be Subset of TOP-REAL n;
A1: the TopStruct of TOP-REAL n = TopSpaceMetr Euclid n by EUCLID:def 8;
  then reconsider PP = P as Subset of TopSpaceMetr Euclid n;
  u in Int PP iff ex r being Real st r > 0 & Ball(u,r) c= PP by Th4;
  hence thesis by A1,Lm5;
end;

theorem Th6: :: TOPREAL3:12
  for u,v being Point of Euclid 2 st u = |[r1,s1]| & v = |[r2,s2]|
  holds dist(u,v) =sqrt ((r1 - r2)^2 + (s1 - s2)^2)
proof
  let u,v be Point of Euclid 2 such that
A1: u = |[r1,s1]| & v = |[r2,s2]|;
A2: |[r1,s1]|`1 = r1 & |[r1,s1]|`2 = s1 by EUCLID:52;
A3: |[r2,s2]|`1 = r2 & |[r2,s2]|`2 = s2 by EUCLID:52;
  thus dist(u,v) = (Pitag_dist 2).(u,v) by METRIC_1:def 1
    .= sqrt ((r1 - r2)^2 + (s1 - s2)^2) by A1,A2,A3,TOPREAL3:7;
end;

theorem Th7:
  for u being Point of Euclid 2 st u = |[r,s]| holds 0 <= r2 & r2
  < r1 implies |[r+r2,s]| in Ball(u,r1)
proof
  let u be Point of Euclid 2 such that
A1: u = |[r,s]| and
A2: 0 <= r2 and
A3: r2 < r1;
  reconsider v = |[r+r2,s]| as Point of Euclid 2 by TOPREAL3:8;
  dist(u,v) = sqrt ((r - (r+r2))^2 + (s - s)^2) by A1,Th6
    .= sqrt ((-(r - (r+r2)))^2)
    .= r2 by A2,SQUARE_1:22;
  hence thesis by A3,METRIC_1:11;
end;

theorem Th8:
  for u being Point of Euclid 2 st u = |[r,s]| holds 0 <= s2 & s2
  < s1 implies |[r,s+s2]| in Ball(u,s1)
proof
  let u be Point of Euclid 2 such that
A1: u = |[r,s]| and
A2: 0 <= s2 and
A3: s2 < s1;
  reconsider v = |[r,s+s2]| as Point of Euclid 2 by TOPREAL3:8;
  dist(u,v) = sqrt ((r - r)^2 + (s - (s+s2))^2) by A1,Th6
    .= sqrt ((-(s - (s+s2)))^2)
    .= s2 by A2,SQUARE_1:22;
  hence thesis by A3,METRIC_1:11;
end;

theorem Th9:
  for u being Point of Euclid 2 st u = |[r,s]| holds 0 <= r2 & r2
  < r1 implies |[r-r2,s]| in Ball(u,r1)
proof
  let u be Point of Euclid 2 such that
A1: u = |[r,s]| and
A2: 0 <= r2 and
A3: r2 < r1;
  reconsider v = |[r-r2,s]| as Point of Euclid 2 by TOPREAL3:8;
  dist(u,v) = sqrt ((r - (r-r2))^2 + (s - s)^2) by A1,Th6
    .= r2 by A2,SQUARE_1:22;
  hence thesis by A3,METRIC_1:11;
end;

theorem Th10:
  for u being Point of Euclid 2 st u = |[r,s]| holds 0 <= s2 & s2
  < s1 implies |[r,s-s2]| in Ball(u,s1)
proof
  let u be Point of Euclid 2 such that
A1: u = |[r,s]| and
A2: 0 <= s2 and
A3: s2 < s1;
  reconsider v = |[r,s-s2]| as Point of Euclid 2 by TOPREAL3:8;
  dist(u,v) = sqrt ((s - (s-s2))^2 + (r - r)^2) by A1,Th6
    .= s2 by A2,SQUARE_1:22;
  hence thesis by A3,METRIC_1:11;
end;

theorem Th11:
  1 <= i & i < len G & 1 <= j & j < width G implies G*(i,j)+G*(i+1
  ,j+1) = G*(i,j+1)+G*(i+1,j)
proof
  assume that
A1: 1 <= i & i < len G and
A2: 1 <= j & j < width G;
A3: 1 <= j+1 & j+1 <= width G by A2,NAT_1:13;
A4: 1 <= i+1 & i+1 <= len G by A1,NAT_1:13;
  then
A5: G*(i+1,j+1)`1 = G*(i+1,1)`1 by A3,GOBOARD5:2
    .= G*(i+1,j)`1 by A2,A4,GOBOARD5:2;
A6: G*(i+1,j+1)`2 = G*(1,j+1)`2 by A4,A3,GOBOARD5:1
    .= G*(i,j+1)`2 by A1,A3,GOBOARD5:1;
A7: G*(i,j)`2 = G*(1,j)`2 by A1,A2,GOBOARD5:1
    .= G*(i+1,j)`2 by A2,A4,GOBOARD5:1;
A8: (G*(i,j)+G*(i+1,j+1))`2 = G*(i,j)`2+G*(i+1,j+1)`2 by Lm1
    .= (G*(i,j+1)+G*(i+1,j))`2 by A7,A6,Lm1;
A9: G*(i,j)`1 = G*(i,1)`1 by A1,A2,GOBOARD5:2
    .= G*(i,j+1)`1 by A1,A3,GOBOARD5:2;
  (G*(i,j)+G*(i+1,j+1))`1 = G*(i,j)`1+G*(i+1,j+1)`1 by Lm1
    .= (G*(i,j+1)+G*(i+1,j))`1 by A9,A5,Lm1;
  hence
  G*(i,j)+G*(i+1,j+1) = |[(G*(i,j+1)+G*(i+1,j))`1,(G*(i,j+1)+G*(i+1,j))`2
  ]| by A8,EUCLID:53
    .= G*(i,j+1)+G*(i+1,j) by EUCLID:53;
end;

Lm6: the TopStruct of TOP-REAL 2 = TopSpaceMetr Euclid 2 by EUCLID:def 8
  .= TopStruct (#the carrier of Euclid 2,Family_open_set Euclid 2#) by
PCOMPS_1:def 5;

theorem Th12:
  Int v_strip(G,0) = { |[r,s]| : r < G*(1,1)`1 }
proof
  0 <> width G by MATRIX_0:def 10;
  then 1 <= width G by NAT_1:14;
  then
A1: v_strip(G,0) = { |[r,s]| : r <= G*(1,1)`1 } by GOBOARD5:10;
  thus Int v_strip(G,0) c= { |[r,s]| : r < G*(1,1)`1 }
  proof
    let x be object;
    assume
A2: x in Int v_strip(G,0);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider r1 being Real such that
A3: r1 > 0 and
A4: Ball(u,r1) c= v_strip(G,0) by A2,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A5: p = |[p`1,p`2]| by EUCLID:53;
    set q = |[p`1+r1/2,p`2+0]|;
    r1/2 < r1 by A3,XREAL_1:216;
    then q in Ball(u,r1) by A3,A5,Th7;
    then q in v_strip(G,0) by A4;
    then ex r2,s2 st q = |[r2,s2]| & r2 <= G*(1,1)`1 by A1;
    then
A6: p`1+r1/2 <= G*(1,1)`1 by SPPOL_2:1;
    p`1 < p`1 + r1/2 by A3,XREAL_1:29,215;
    then p`1 < G*(1,1)`1 by A6,XXREAL_0:2;
    hence thesis by A5;
  end;
  let x be object;
  assume x in { |[r,s]| : r < G*(1,1)`1 };
  then consider r,s such that
A7: x = |[r,s]| and
A8: r < G*(1,1)`1;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
A9: Ball(u,G*(1,1)`1-r) c= v_strip(G,0)
  proof
    let y be object;
A10: Ball(u,G*(1,1)`1-r) = { v : dist(u,v)<G*(1,1)`1-r} by METRIC_1:17;
    assume y in Ball(u,G*(1,1)`1-r);
    then consider v such that
A11: v = y and
A12: dist(u,v)<G*(1,1)`1-r by A10;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (r - q`1)^2 >= 0 & (r - q`1)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A13: sqrt (r - q`1)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A14: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < G*(1,1)`1-r by A12,Th6;
    then sqrt (r - q`1)^2 <= G*(1,1)`1-r by A13,XXREAL_0:2;
    then
A15: |.r-q`1.| <= G*(1,1)`1-r by COMPLEX1:72;
    per cases;
    suppose
      r <= q`1;
      then
A16:  q`1-r >= 0 by XREAL_1:48;
      |.r-q`1.| = |.-(r-q`1).| by COMPLEX1:52
        .= q`1 - r by A16,ABSVALUE:def 1;
      then q`1 <= G*(1,1)`1 by A15,XREAL_1:9;
      hence thesis by A1,A11,A14;
    end;
    suppose
      r >= q`1;
      then q`1 <= G*(1,1)`1 by A8,XXREAL_0:2;
      hence thesis by A1,A11,A14;
    end;
  end;
  reconsider B = Ball(u,G*(1,1)`1-r) as Subset of TOP-REAL2 by TOPREAL3:8;
A17: B is open by Th3;
  u in Ball(u,G*(1,1)`1-r) by A8,Th1,XREAL_1:50;
  hence thesis by A7,A9,A17,TOPS_1:22;
end;

theorem Th13:
  Int v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 < r }
proof
  0 <> width G by MATRIX_0:def 10;
  then 1 <= width G by NAT_1:14;
  then
A1: v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 <= r } by GOBOARD5:9;
  thus Int v_strip(G,len G) c= { |[r,s]| : G*(len G,1)`1 < r }
  proof
    let x be object;
    assume
A2: x in Int v_strip(G,len G);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider r1 being Real such that
A3: r1 > 0 and
A4: Ball(u,r1) c= v_strip(G,len G) by A2,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A5: p = |[p`1,p`2]| by EUCLID:53;
    set q = |[p`1-r1/2,p`2+0]|;
    r1/2 < r1 by A3,XREAL_1:216;
    then q in Ball(u,r1) by A3,A5,Th9;
    then q in v_strip(G,len G) by A4;
    then ex r2,s2 st q = |[r2,s2]| & G*(len G,1)`1 <= r2 by A1;
    then G*(len G,1)`1 <= p`1-r1/2 by SPPOL_2:1;
    then
A6: G*(len G,1)`1+r1/2 <= p`1 by XREAL_1:19;
    G*(len G,1)`1 < G*(len G,1)`1 + r1/2 by A3,XREAL_1:29,215;
    then G*(len G,1)`1 < p`1 by A6,XXREAL_0:2;
    hence thesis by A5;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(len G,1)`1 < r };
  then consider r,s such that
A7: x = |[r,s]| and
A8: G*(len G,1)`1 < r;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
A9: Ball(u,r-G*(len G,1)`1) c= v_strip(G,len G)
  proof
    let y be object;
A10: Ball(u,r-G*(len G,1)`1) = { v : dist(u,v)<r-G*(len G,1)`1} by METRIC_1:17;
    assume y in Ball(u,r-G*(len G,1)`1);
    then consider v such that
A11: v = y and
A12: dist(u,v)<r-G*(len G,1)`1 by A10;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (r - q`1)^2 >= 0 & (r - q`1)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A13: sqrt (r - q`1)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A14: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < r-G*(len G,1)`1 by A12,Th6;
    then sqrt (r - q`1)^2 <= r-G*(len G,1)`1 by A13,XXREAL_0:2;
    then
A15: |.r-q`1.| <= r-G*(len G,1)`1 by COMPLEX1:72;
    per cases;
    suppose
      r >= q`1;
      then r-q`1 >= 0 by XREAL_1:48;
      then |.r-q`1.| = r - q`1 by ABSVALUE:def 1;
      then G*(len G,1)`1 <= q`1 by A15,XREAL_1:10;
      hence thesis by A1,A11,A14;
    end;
    suppose
      r <= q`1;
      then G*(len G,1)`1 <= q`1 by A8,XXREAL_0:2;
      hence thesis by A1,A11,A14;
    end;
  end;
  reconsider B = Ball(u,r-G*(len G,1)`1) as Subset of TOP-REAL2 by TOPREAL3:8;
A16: B is open by Th3;
  u in Ball(u,r-G*(len G,1)`1) by A8,Th1,XREAL_1:50;
  hence thesis by A7,A9,A16,TOPS_1:22;
end;

theorem Th14:
  1 <= i & i < len G implies Int v_strip(G,i) = { |[r,s]| : G*(i,1
  )`1 < r & r < G*(i+1,1)`1 }
proof
  0 <> width G by MATRIX_0:def 10;
  then
A1: 1 <= width G by NAT_1:14;
  assume 1 <= i & i < len G;
  then
A2: v_strip(G,i) = { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 } by A1,
GOBOARD5:8;
  thus Int v_strip(G,i) c= { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 }
  proof
    let x be object;
    assume
A3: x in Int v_strip(G,i);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider r1 being Real such that
A4: r1 > 0 and
A5: Ball(u,r1) c= v_strip(G,i) by A3,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A6: p = |[p`1,p`2]| by EUCLID:53;
    set q2 = |[p`1-r1/2,p`2+0]|;
A7: r1/2 < r1 by A4,XREAL_1:216;
    then q2 in Ball(u,r1) by A4,A6,Th9;
    then q2 in v_strip(G,i) by A5;
    then ex r2,s2 st q2 = |[r2,s2]| & G*(i,1)`1 <= r2 & r2 <= G*(i+1,1)`1 by A2
;
    then G*(i,1)`1 <= p`1-r1/2 by SPPOL_2:1;
    then
A8: G*(i,1)`1+r1/2 <= p`1 by XREAL_1:19;
    set q1 = |[p`1+r1/2,p`2+0]|;
    q1 in Ball(u,r1) by A4,A6,A7,Th7;
    then q1 in v_strip(G,i) by A5;
    then ex r2,s2 st q1 = |[r2,s2]| & G*(i,1)`1 <= r2 & r2 <= G*(i+1,1)`1 by A2
;
    then
A9: p`1+r1/2 <= G*(i+1,1)`1 by SPPOL_2:1;
    G*(i,1)`1 < G*(i,1)`1 + r1/2 by A4,XREAL_1:29,215;
    then
A10: G*(i,1)`1 < p`1 by A8,XXREAL_0:2;
    p`1 < p`1 + r1/2 by A4,XREAL_1:29,215;
    then p`1 < G*(i+1,1)`1 by A9,XXREAL_0:2;
    hence thesis by A6,A10;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 };
  then consider r,s such that
A11: x = |[r,s]| and
A12: G*(i,1)`1 < r and
A13: r < G*(i+1,1)`1;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
  G*(i+1,1)`1-r > 0 & r - G*(i,1)`1 > 0 by A12,A13,XREAL_1:50;
  then min(r-G*(i,1)`1,G*(i+1,1)`1-r) > 0 by XXREAL_0:15;
  then
A14: u in Ball(u,min(r-G*(i,1)`1,G*(i+1,1)`1-r)) by Th1;
A15: Ball(u,min(r-G*(i,1)`1,G*(i+1,1)`1-r)) c= v_strip(G,i)
  proof
    let y be object;
A16: Ball(u,min(r-G*(i,1)`1,G*(i+1,1)`1-r)) = { v : dist(u,v)<min(r-G*(i,1
    )`1,G*(i+1,1)`1-r)} by METRIC_1:17;
    assume y in Ball(u,min(r-G*(i,1)`1,G*(i+1,1)`1-r));
    then consider v such that
A17: v = y and
A18: dist(u,v)<min(r-G*(i,1)`1,G*(i+1,1)`1-r) by A16;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (r - q`1)^2 >= 0 & (r - q`1)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A19: sqrt (r - q`1)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A20: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < min(r-G*(i,1)`1,G*(i+1,1 )`1-r )
    by A18,Th6;
    then sqrt (r - q`1)^2 <= min(r-G*(i,1)`1,G* (i+1,1)`1-r) by A19,XXREAL_0:2;
    then
A21: |.r-q`1.| <= min(r-G*(i,1)`1,G*(i+1,1)`1-r) by COMPLEX1:72;
    then
A22: |.r-q`1.| <= r-G*(i,1)`1 by XXREAL_0:22;
A23: |.r-q`1.| <= G* (i+1,1)`1-r by A21,XXREAL_0:22;
    per cases;
    suppose
A24:  r <= q`1;
      then
A25:  q`1-r >= 0 by XREAL_1:48;
      |.r-q`1.| = |.-(r-q`1).| by COMPLEX1:52
        .= q`1 - r by A25,ABSVALUE:def 1;
      then
A26:  q`1 <= G*(i+1,1)`1 by A23,XREAL_1:9;
      G*(i,1)`1 <= q`1 by A12,A24,XXREAL_0:2;
      hence thesis by A2,A17,A20,A26;
    end;
    suppose
A27:  r >= q`1;
      then r-q`1 >= 0 by XREAL_1:48;
      then |.r-q`1.| = r - q`1 by ABSVALUE:def 1;
      then
A28:  G*(i,1)`1 <= q`1 by A22,XREAL_1:10;
      q`1 <= G*(i+1,1)`1 by A13,A27,XXREAL_0:2;
      hence thesis by A2,A17,A20,A28;
    end;
  end;
  reconsider B = Ball(u,min(r-G*(i,1)`1,G*(i+1,1)`1-r)) as Subset of TOP-REAL2
  by TOPREAL3:8;
  B is open by Th3;
  hence thesis by A11,A14,A15,TOPS_1:22;
end;

theorem Th15:
  Int h_strip(G,0) = { |[r,s]| : s < G*(1,1)`2 }
proof
  0 <> len G by MATRIX_0:def 10;
  then 1 <= len G by NAT_1:14;
  then
A1: h_strip(G,0) = { |[r,s]| : s <= G*(1,1)`2 } by GOBOARD5:7;
  thus Int h_strip(G,0) c= { |[r,s]| : s < G*(1,1)`2 }
  proof
    let x be object;
    assume
A2: x in Int h_strip(G,0);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider s1 being Real such that
A3: s1 > 0 and
A4: Ball(u,s1) c= h_strip(G,0) by A2,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A5: p = |[p`1,p`2]| by EUCLID:53;
    set q = |[p`1+0,p`2+s1/2]|;
    s1/2 < s1 by A3,XREAL_1:216;
    then q in Ball(u,s1) by A3,A5,Th8;
    then q in h_strip(G,0) by A4;
    then ex r2,s2 st q = |[r2,s2]| & s2 <= G*(1,1)`2 by A1;
    then
A6: p`2+s1/2 <= G*(1,1)`2 by SPPOL_2:1;
    p`2 < p`2 + s1/2 by A3,XREAL_1:29,215;
    then p`2 < G*(1,1)`2 by A6,XXREAL_0:2;
    hence thesis by A5;
  end;
  let x be object;
  assume x in { |[r,s]| : s < G*(1,1)`2 };
  then consider r,s such that
A7: x = |[r,s]| and
A8: s < G*(1,1)`2;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
A9: Ball(u,G*(1,1)`2-s) c= h_strip(G,0)
  proof
    let y be object;
A10: Ball(u,G*(1,1)`2-s) = { v : dist(u,v)<G*(1,1)`2-s} by METRIC_1:17;
    assume y in Ball(u,G*(1,1)`2-s);
    then consider v such that
A11: v = y and
A12: dist(u,v)<G*(1,1)`2-s by A10;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (s - q`2)^2 >= 0 & (s - q`2)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A13: sqrt (s - q`2)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A14: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < G*(1,1)`2-s by A12,Th6;
    then sqrt (s - q`2)^2 <= G*(1,1)`2-s by A13,XXREAL_0:2;
    then
A15: |.s-q`2.| <= G*(1,1)`2-s by COMPLEX1:72;
    per cases;
    suppose
      s <= q`2;
      then
A16:  q`2-s >= 0 by XREAL_1:48;
      |.s-q`2.| = |.-(s-q`2).| by COMPLEX1:52
        .= q`2 - s by A16,ABSVALUE:def 1;
      then q`2 <= G*(1,1)`2 by A15,XREAL_1:9;
      hence thesis by A1,A11,A14;
    end;
    suppose
      s >= q`2;
      then q`2 <= G*(1,1)`2 by A8,XXREAL_0:2;
      hence thesis by A1,A11,A14;
    end;
  end;
  reconsider B = Ball(u,G*(1,1)`2-s) as Subset of TOP-REAL2 by TOPREAL3:8;
A17: B is open by Th3;
  u in Ball(u,G*(1,1)`2-s) by A8,Th1,XREAL_1:50;
  hence thesis by A7,A9,A17,TOPS_1:22;
end;

theorem Th16:
  Int h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 < s }
proof
  0 <> len G by MATRIX_0:def 10;
  then 1 <= len G by NAT_1:14;
  then
A1: h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 <= s } by GOBOARD5:6;
  thus Int h_strip(G,width G) c= { |[r,s]| : G*(1,width G)`2 < s }
  proof
    let x be object;
    assume
A2: x in Int h_strip(G,width G);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider s1 being Real such that
A3: s1 > 0 and
A4: Ball(u,s1) c= h_strip(G,width G) by A2,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A5: p = |[p`1,p`2]| by EUCLID:53;
    set q = |[p`1+0,p`2-s1/2]|;
    s1/2 < s1 by A3,XREAL_1:216;
    then q in Ball(u,s1) by A3,A5,Th10;
    then q in h_strip(G,width G) by A4;
    then ex r2,s2 st q = |[r2,s2]| & G*(1,width G)`2 <= s2 by A1;
    then G*(1,width G)`2 <= p`2-s1/2 by SPPOL_2:1;
    then
A6: G*(1,width G)`2+s1/2 <= p`2 by XREAL_1:19;
    G*(1,width G)`2 < G*(1,width G)`2 + s1/2 by A3,XREAL_1:29,215;
    then G*(1,width G)`2 < p`2 by A6,XXREAL_0:2;
    hence thesis by A5;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(1,width G)`2 < s };
  then consider r,s such that
A7: x = |[r,s]| and
A8: G*(1,width G)`2 < s;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
A9: Ball(u,s-G*(1,width G)`2) c= h_strip(G,width G)
  proof
    let y be object;
A10: Ball(u,s-G*(1,width G)`2) = { v : dist(u,v)<s-G*(1,width G)`2} by
METRIC_1:17;
    assume y in Ball(u,s-G*(1,width G)`2);
    then consider v such that
A11: v = y and
A12: dist(u,v)<s-G*(1,width G)`2 by A10;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (s - q`2)^2 >= 0 & (s - q`2)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A13: sqrt (s - q`2)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A14: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < s-G*(1,width G)`2 by A12,Th6;
    then sqrt (s - q`2)^2 <= s-G*(1,width G)`2 by A13,XXREAL_0:2;
    then
A15: |.s-q`2.| <= s-G*(1,width G)`2 by COMPLEX1:72;
    per cases;
    suppose
      s >= q`2;
      then s-q`2 >= 0 by XREAL_1:48;
      then |.s-q`2.| = s - q`2 by ABSVALUE:def 1;
      then G*(1,width G)`2 <= q`2 by A15,XREAL_1:10;
      hence thesis by A1,A11,A14;
    end;
    suppose
      s <= q`2;
      then G*(1,width G)`2 <= q`2 by A8,XXREAL_0:2;
      hence thesis by A1,A11,A14;
    end;
  end;
  reconsider B = Ball(u,s-G*(1,width G)`2) as Subset of TOP-REAL2 by TOPREAL3:8
;
A16: B is open by Th3;
  u in Ball(u,s-G*(1,width G)`2) by A8,Th1,XREAL_1:50;
  hence thesis by A7,A9,A16,TOPS_1:22;
end;

theorem Th17:
  1 <= j & j < width G implies Int h_strip(G,j) = { |[r,s]| : G*(1
  ,j)`2 < s & s < G*(1,j+1)`2 }
proof
  0 <> len G by MATRIX_0:def 10;
  then
A1: 1 <= len G by NAT_1:14;
  assume 1 <= j & j < width G;
  then
A2: h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } by A1,
GOBOARD5:5;
  thus Int h_strip(G,j) c= { |[r,s]| : G*(1,j)`2 < s & s < G*(1,j+1)`2 }
  proof
    let x be object;
    assume
A3: x in Int h_strip(G,j);
    then reconsider u = x as Point of Euclid 2 by Lm6;
    consider s1 being Real such that
A4: s1 > 0 and
A5: Ball(u,s1) c= h_strip(G,j) by A3,Th5;
    reconsider p = u as Point of TOP-REAL 2 by Lm6;
A6: p = |[p`1,p`2]| by EUCLID:53;
    set q2 = |[p`1+0,p`2-s1/2]|;
A7: s1/2 < s1 by A4,XREAL_1:216;
    then q2 in Ball(u,s1) by A4,A6,Th10;
    then q2 in h_strip(G,j) by A5;
    then ex r2,s2 st q2 = |[r2,s2]| & G*(1,j)`2 <= s2 & s2 <= G*(1,j+1)`2 by A2
;
    then G*(1,j)`2 <= p`2-s1/2 by SPPOL_2:1;
    then
A8: G*(1,j)`2+s1/2 <= p`2 by XREAL_1:19;
    set q1 = |[p`1+0,p`2+s1/2]|;
    q1 in Ball(u,s1) by A4,A6,A7,Th8;
    then q1 in h_strip(G,j) by A5;
    then ex r2,s2 st q1 = |[r2,s2]| & G*(1,j)`2 <= s2 & s2 <= G*(1,j+1)`2 by A2
;
    then
A9: p`2+s1/2 <= G*(1,j+1)`2 by SPPOL_2:1;
    G*(1,j)`2 < G*(1,j)`2 + s1/2 by A4,XREAL_1:29,215;
    then
A10: G*(1,j)`2 < p`2 by A8,XXREAL_0:2;
    p`2 < p`2 + s1/2 by A4,XREAL_1:29,215;
    then p`2 < G*(1,j+1)`2 by A9,XXREAL_0:2;
    hence thesis by A6,A10;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(1,j)`2 < s & s < G*(1,j+1)`2 };
  then consider r,s such that
A11: x = |[r,s]| and
A12: G*(1,j)`2 < s and
A13: s < G*(1,j+1)`2;
  reconsider u = |[r,s]| as Point of Euclid 2 by TOPREAL3:8;
  G*(1,j+1)`2-s > 0 & s - G*(1,j)`2 > 0 by A12,A13,XREAL_1:50;
  then min(s-G*(1,j)`2,G*(1,j+1)`2-s) > 0 by XXREAL_0:15;
  then
A14: u in Ball(u,min(s-G*(1,j)`2,G*(1,j+1)`2-s)) by Th1;
A15: Ball(u,min(s-G*(1,j)`2,G*(1,j+1)`2-s)) c= h_strip(G,j)
  proof
    let y be object;
A16: Ball(u,min(s-G*(1,j)`2,G*(1,j+1)`2-s)) = { v : dist(u,v)<min(s-G*(1,j
    )`2,G*(1,j+1)`2-s)} by METRIC_1:17;
    assume y in Ball(u,min(s-G*(1,j)`2,G*(1,j+1)`2-s));
    then consider v such that
A17: v = y and
A18: dist(u,v)<min(s-G*(1,j)`2,G*(1,j+1)`2-s) by A16;
    reconsider q = v as Point of TOP-REAL 2 by TOPREAL3:8;
    (s - q`2)^2 >= 0 & (s - q`2)^2 + 0 <= (r - q`1)^2 + (s - q`2)^2 by
XREAL_1:6,63;
    then
A19: sqrt (s - q`2)^2 <= sqrt ((r - q`1)^2 + (s - q`2)^2) by SQUARE_1:26;
A20: q = |[q`1,q`2]| by EUCLID:53;
    then sqrt ((r - q`1)^2 + (s - q`2)^2) < min(s-G*(1,j)`2,G*(1,j+1 )`2-s )
    by A18,Th6;
    then sqrt (s - q`2)^2 <= min(s-G*(1,j)`2,G* (1,j+1)`2-s) by A19,XXREAL_0:2;
    then
A21: |.s-q`2.| <= min(s-G*(1,j)`2,G*(1,j+1)`2-s) by COMPLEX1:72;
    then
A22: |.s-q`2.| <= s-G*(1,j)`2 by XXREAL_0:22;
A23: |.s-q`2.| <= G* (1,j+1)`2-s by A21,XXREAL_0:22;
    per cases;
    suppose
A24:  s <= q`2;
      then
A25:  q`2-s >= 0 by XREAL_1:48;
      |.s-q`2.| = |.-(s-q`2).| by COMPLEX1:52
        .= q`2 - s by A25,ABSVALUE:def 1;
      then
A26:  q`2 <= G*(1,j+1)`2 by A23,XREAL_1:9;
      G*(1,j)`2 <= q`2 by A12,A24,XXREAL_0:2;
      hence thesis by A2,A17,A20,A26;
    end;
    suppose
A27:  s >= q`2;
      then s-q`2 >= 0 by XREAL_1:48;
      then |.s-q`2.| = s - q`2 by ABSVALUE:def 1;
      then
A28:  G*(1,j)`2 <= q`2 by A22,XREAL_1:10;
      q`2 <= G*(1,j+1)`2 by A13,A27,XXREAL_0:2;
      hence thesis by A2,A17,A20,A28;
    end;
  end;
  reconsider B = Ball(u,min(s-G*(1,j)`2,G*(1,j+1)`2-s)) as Subset of TOP-REAL2
  by TOPREAL3:8;
  B is open by Th3;
  hence thesis by A11,A14,A15,TOPS_1:22;
end;

theorem Th18:
  Int cell(G,0,0) = { |[r,s]| : r < G*(1,1)`1 & s < G*(1,1)`2 }
proof
  cell(G,0,0) = v_strip(G,0) /\ h_strip(G,0) by GOBOARD5:def 3;
  then
A1: Int cell(G,0,0) = Int v_strip(G,0) /\ Int h_strip(G,0) by TOPS_1:17;
A2: Int h_strip(G,0) = { |[r,s]| : s < G*(1,1)`2 } by Th15;
A3: Int v_strip(G,0) = { |[r,s]| : r < G*(1,1)`1 } by Th12;
  thus Int cell(G,0,0) c= { |[r,s]| : r < G*(1,1)`1 & s < G*(1,1)`2 }
  proof
    let x be object;
    assume
A4: x in Int cell(G,0,0);
    then x in Int v_strip(G,0) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: r1 < G*(1,1)`1 by A3;
    x in Int h_strip(G,0) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: s2 < G*(1,1)`2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : r < G*(1,1)`1 & s < G*(1,1)`2 };
  then
A9: ex r,s st x = |[r,s]| & r < G*(1,1)`1 & s < G*(1,1)`2;
  then
A10: x in Int h_strip(G,0) by A2;
  x in Int v_strip(G,0) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th19:
  Int cell(G,0,width G) = { |[r,s]| : r < G*(1,1)`1 & G*(1,width G )`2 < s }
proof
  cell(G,0,width G) = v_strip(G,0) /\ h_strip(G,width G) by GOBOARD5:def 3;
  then
A1: Int cell(G,0,width G) = Int v_strip(G,0) /\ Int h_strip(G,width G) by
TOPS_1:17;
A2: Int h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 < s } by Th16;
A3: Int v_strip(G,0) = { |[r,s]| : r < G*(1,1)`1 } by Th12;
  thus Int cell(G,0,width G) c= { |[r,s]| : r < G*(1,1)`1 & G*(1,width G)`2 <
  s }
  proof
    let x be object;
    assume
A4: x in Int cell(G,0,width G);
    then x in Int v_strip(G,0) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: r1 < G*(1,1)`1 by A3;
    x in Int h_strip(G,width G) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: G*(1,width G)`2 < s2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : r < G*(1,1)`1 & G*(1,width G)`2 < s };
  then
A9: ex r,s st x = |[r,s]| & r < G*(1,1)`1 & G*(1,width G)`2 < s;
  then
A10: x in Int h_strip(G,width G) by A2;
  x in Int v_strip(G,0) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th20:
  1 <= j & j < width G implies Int cell(G,0,j) = { |[r,s]| : r < G
  *(1,1)`1 & G*(1,j)`2 < s & s < G*(1,j+1)`2 }
proof
  cell(G,0,j) = v_strip(G,0) /\ h_strip(G,j) by GOBOARD5:def 3;
  then
A1: Int cell(G,0,j) = Int v_strip(G,0) /\ Int h_strip(G,j) by TOPS_1:17;
  assume 1 <= j & j < width G;
  then
A2: Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s & s < G* (1,j+1)`2 } by Th17;
A3: Int v_strip(G,0) = { |[r,s]| : r < G*(1,1)`1 } by Th12;
  thus Int cell(G,0,j) c= { |[r,s]| : r < G*(1,1)`1 & G*(1,j)`2 < s & s < G*(1
  ,j+1)`2 }
  proof
    let x be object;
    assume
A4: x in Int cell(G,0,j);
    then x in Int v_strip(G,0) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: r1 < G*(1,1)`1 by A3;
    x in Int h_strip(G,j) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: G*(1,j)`2 < s2 & s2 < G*(1,j+1)`2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : r < G*(1,1)`1 & G*(1,j)`2 < s & s < G*(1,j+1)`2 };
  then
A9: ex r,s st x = |[r,s]| & r < G*(1,1)`1 & G*(1,j)`2 < s & s < G*(1,j+1)`2;
  then
A10: x in Int h_strip(G,j) by A2;
  x in Int v_strip(G,0) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th21:
  Int cell(G,len G,0) = { |[r,s]| : G*(len G,1)`1 < r & s < G*(1,1 )`2 }
proof
  cell(G,len G,0) = v_strip(G,len G) /\ h_strip(G,0) by GOBOARD5:def 3;
  then
A1: Int cell(G,len G,0) = Int v_strip(G,len G) /\ Int h_strip(G,0) by TOPS_1:17
;
A2: Int h_strip(G,0) = { |[r,s]| : s < G*(1,1)`2 } by Th15;
A3: Int v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 < r } by Th13;
  thus Int cell(G,len G,0) c= { |[r,s]| : G*(len G,1)`1 < r & s < G*(1,1)`2 }
  proof
    let x be object;
    assume
A4: x in Int cell(G,len G,0);
    then x in Int v_strip(G,len G) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: G*(len G,1)`1 < r1 by A3;
    x in Int h_strip(G,0) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: s2 < G*(1,1)`2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(len G,1)`1 < r & s < G*(1,1)`2 };
  then
A9: ex r,s st x = |[r,s]| & G*(len G,1)`1 < r & s < G*(1,1)`2;
  then
A10: x in Int h_strip(G,0) by A2;
  x in Int v_strip(G,len G) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th22:
  Int cell(G,len G,width G) = { |[r,s]| : G*(len G,1)`1 < r & G*(1
  ,width G)`2 < s }
proof
  cell(G,len G,width G) = v_strip(G,len G) /\ h_strip(G,width G) by
GOBOARD5:def 3;
  then
A1: Int cell(G,len G,width G) = Int v_strip(G,len G) /\ Int h_strip(G, width
  G) by TOPS_1:17;
A2: Int h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 < s } by Th16;
A3: Int v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 < r } by Th13;
  thus Int cell(G,len G,width G) c= { |[r,s]| : G*(len G,1)`1 < r & G*(1,width
  G)`2 < s }
  proof
    let x be object;
    assume
A4: x in Int cell(G,len G,width G);
    then x in Int v_strip(G,len G) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: G*(len G,1)`1 < r1 by A3;
    x in Int h_strip(G,width G) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: G*(1,width G)`2 < s2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(len G,1)`1 < r & G*(1,width G)`2 < s };
  then
A9: ex r,s st x = |[r,s]| & G*(len G,1)`1 < r & G*(1,width G)`2 < s;
  then
A10: x in Int h_strip(G,width G) by A2;
  x in Int v_strip(G,len G) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th23:
  1 <= j & j < width G implies Int cell(G,len G,j) = { |[r,s]| : G
  *(len G,1)`1 < r & G*(1,j)`2 < s & s < G*(1,j+1)`2 }
proof
  cell(G,len G,j) = v_strip(G,len G) /\ h_strip(G,j) by GOBOARD5:def 3;
  then
A1: Int cell(G,len G,j) = Int v_strip(G,len G) /\ Int h_strip(G,j) by TOPS_1:17
;
  assume 1 <= j & j < width G;
  then
A2: Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s & s < G* (1,j+1)`2 } by Th17;
A3: Int v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 < r } by Th13;
  thus Int cell(G,len G,j) c= { |[r,s]| : G*(len G,1)`1 < r & G*(1,j)`2 < s &
  s < G*(1,j+1)`2 }
  proof
    let x be object;
    assume
A4: x in Int cell(G,len G,j);
    then x in Int v_strip(G,len G) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: G*(len G,1)`1 < r1 by A3;
    x in Int h_strip(G,j) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: G*(1,j)`2 < s2 & s2 < G*(1,j+1)`2 by A2;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume
  x in { |[r,s]| : G*(len G,1)`1 < r & G*(1,j)`2 < s & s < G* (1,j+1) `2 };
  then
A9: ex r,s st x = |[r,s]| & G*(len G,1)`1 < r & G*(1,j)`2 < s & s < G*(1,j+
  1)`2;
  then
A10: x in Int h_strip(G,j) by A2;
  x in Int v_strip(G,len G) by A3,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th24:
  1 <= i & i < len G implies Int cell(G,i,0) = { |[r,s]| : G*(i,1)
  `1 < r & r < G*(i+1,1)`1 & s < G*(1,1)`2 }
proof
  cell(G,i,0) = v_strip(G,i) /\ h_strip(G,0) by GOBOARD5:def 3;
  then
A1: Int cell(G,i,0) = Int v_strip(G,i) /\ Int h_strip(G,0) by TOPS_1:17;
  assume 1 <= i & i < len G;
  then
A2: Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r & r < G* (i+1,1)`1 } by Th14;
A3: Int h_strip(G,0) = { |[r,s]| : s < G*(1,1)`2 } by Th15;
  thus Int cell(G,i,0) c= { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & s < G*
  (1,1)`2 }
  proof
    let x be object;
    assume
A4: x in Int cell(G,i,0);
    then x in Int v_strip(G,i) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 by A2;
    x in Int h_strip(G,0) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: s2 < G*(1,1)`2 by A3;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & s < G*(1,1)`2 };
  then
A9: ex r,s st x = |[r,s]| & G*(i,1)`1 < r & r < G*(i+1,1)`1 & s < G*(1,1)`2;
  then
A10: x in Int h_strip(G,0) by A3;
  x in Int v_strip(G,i) by A2,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th25:
  1 <= i & i < len G implies Int cell(G,i,width G) = { |[r,s]| : G
  *(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,width G)`2 < s }
proof
  cell(G,i,width G) = v_strip(G,i) /\ h_strip(G,width G) by GOBOARD5:def 3;
  then
A1: Int cell(G,i,width G) = Int v_strip(G,i) /\ Int h_strip(G,width G) by
TOPS_1:17;
  assume 1 <= i & i < len G;
  then
A2: Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r & r < G* (i+1,1)`1 } by Th14;
A3: Int h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 < s } by Th16;
  thus Int cell(G,i,width G) c= { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 &
  G*(1,width G)`2 < s }
  proof
    let x be object;
    assume
A4: x in Int cell(G,i,width G);
    then x in Int v_strip(G,i) by A1,XBOOLE_0:def 4;
    then consider r1,s1 such that
A5: x = |[r1,s1]| and
A6: G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 by A2;
    x in Int h_strip(G,width G) by A1,A4,XBOOLE_0:def 4;
    then consider r2,s2 such that
A7: x = |[r2,s2]| and
A8: G*(1,width G)`2 < s2 by A3;
    s1 = s2 by A5,A7,SPPOL_2:1;
    hence thesis by A5,A6,A8;
  end;
  let x be object;
  assume
  x in { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,width G)`2 < s };
  then
A9: ex r,s st x = |[r,s]| & G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,width G)
  `2 < s;
  then
A10: x in Int h_strip(G,width G) by A3;
  x in Int v_strip(G,i) by A2,A9;
  hence thesis by A1,A10,XBOOLE_0:def 4;
end;

theorem Th26:
  1 <= i & i < len G & 1 <= j & j < width G implies Int cell(G,i,j
) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j)`2 < s & s < G*(1,j+1)
  `2 }
proof
  assume that
A1: 1 <= i & i < len G and
A2: 1 <= j & j < width G;
A3: Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s & s < G* (1,j+1)`2 } by A2
,Th17;
  cell(G,i,j) = v_strip(G,i) /\ h_strip(G,j) by GOBOARD5:def 3;
  then
A4: Int cell(G,i,j) = Int v_strip(G,i) /\ Int h_strip(G,j) by TOPS_1:17;
A5: Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r & r < G* (i+1,1)`1 } by A1
,Th14;
  thus Int cell(G,i,j) c= { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j
  )`2 < s & s < G*(1,j+1)`2 }
  proof
    let x be object;
    assume
A6: x in Int cell(G,i,j);
    then x in Int v_strip(G,i) by A4,XBOOLE_0:def 4;
    then consider r1,s1 such that
A7: x = |[r1,s1]| and
A8: G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 by A5;
    x in Int h_strip(G,j) by A4,A6,XBOOLE_0:def 4;
    then consider r2,s2 such that
A9: x = |[r2,s2]| and
A10: G*(1,j)`2 < s2 & s2 < G*(1,j+1)`2 by A3;
    s1 = s2 by A7,A9,SPPOL_2:1;
    hence thesis by A7,A8,A10;
  end;
  let x be object;
  assume x in { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j)`2 < s &
  s < G*(1,j+1)`2 };
  then
A11: ex r,s st x = |[r,s]| & G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j)`2 < s
  & s < G*(1,j+1)`2;
  then
A12: x in Int h_strip(G,j) by A3;
  x in Int v_strip(G,i) by A5,A11;
  hence thesis by A4,A12,XBOOLE_0:def 4;
end;

theorem
  1 <= j & j <= width G & p in Int h_strip(G,j) implies p`2 > G*(1,j)`2
proof
  assume that
A1: 1 <= j and
A2: j <= width G and
A3: p in Int h_strip(G,j);
  per cases by A2,XXREAL_0:1;
  suppose
    j = width G;
    then Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s } by Th16;
    then ex r,s st p = |[r,s]| & G*(1,j)`2 < s by A3;
    hence thesis by EUCLID:52;
  end;
  suppose
    j < width G;
    then
    Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s & s < G*(1,j+1)`2 } by A1,Th17
;
    then ex r,s st p = |[r,s]| & G*(1,j)`2 < s & s < G*(1,j+1)`2 by A3;
    hence thesis by EUCLID:52;
  end;
end;

theorem
  j < width G & p in Int h_strip(G,j) implies p`2 < G*(1,j+1)`2
proof
  assume that
A1: j < width G and
A2: p in Int h_strip(G,j);
  per cases by NAT_1:14;
  suppose
    j = 0;
    then Int h_strip(G,j) = { |[r,s]| : s < G*(1,j+1)`2 } by Th15;
    then ex r,s st p = |[r,s]| & G*(1,j+1)`2 > s by A2;
    hence thesis by EUCLID:52;
  end;
  suppose
    j >= 1;
    then
    Int h_strip(G,j) = { |[r,s]| : G*(1,j)`2 < s & s < G*(1,j+1)`2 } by A1,Th17
;
    then ex r,s st p = |[r,s]| & G*(1,j)`2 < s & s < G*(1,j+1)`2 by A2;
    hence thesis by EUCLID:52;
  end;
end;

theorem
  1 <= i & i <= len G & p in Int v_strip(G,i) implies p`1 > G*(i,1)`1
proof
  assume that
A1: 1 <= i and
A2: i <= len G and
A3: p in Int v_strip(G,i);
  per cases by A2,XXREAL_0:1;
  suppose
    i = len G;
    then Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r } by Th13;
    then ex r,s st p = |[r,s]| & G*(i,1)`1 < r by A3;
    hence thesis by EUCLID:52;
  end;
  suppose
    i < len G;
    then
    Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 } by A1,Th14
;
    then ex r,s st p = |[r,s]| & G*(i,1)`1 < r & r < G*(i+1,1)`1 by A3;
    hence thesis by EUCLID:52;
  end;
end;

theorem
  i < len G & p in Int v_strip(G,i) implies p`1 < G*(i+1,1)`1
proof
  assume that
A1: i < len G and
A2: p in Int v_strip(G,i);
  per cases by NAT_1:14;
  suppose
    i = 0;
    then Int v_strip(G,i) = { |[r,s]| : r < G*(i+1,1)`1 } by Th12;
    then ex r,s st p = |[r,s]| & G*(i+1,1)`1 > r by A2;
    hence thesis by EUCLID:52;
  end;
  suppose
    i >= 1;
    then
    Int v_strip(G,i) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 } by A1,Th14
;
    then ex r,s st p = |[r,s]| & G*(i,1)`1 < r & r < G*(i+1,1)`1 by A2;
    hence thesis by EUCLID:52;
  end;
end;

theorem Th31:
  1 <= i & i+1 <= len G & 1 <= j & j+1 <= width G implies 1/2*(G*(
  i,j)+G*(i+1,j+1)) in Int cell(G,i,j)
proof
  assume that
A1: 1 <= i and
A2: i+1 <= len G and
A3: 1 <= j and
A4: j+1 <= width G;
A5: j < j+1 by XREAL_1:29;
  set r1 = G*(i,j)`1, s1 = G*(i,j)`2, r2 = G*(i+1,j+1)`1, s2 = G* (i+1,j+1)`2;
A6: 1 <= i+1 & 1 <= j+1 by NAT_1:11;
  then
A7: G*(1,j+1)`2 = s2 by A2,A4,GOBOARD5:1;
  i < len G & j < width G by A2,A4,NAT_1:13;
  then
A8: Int cell(G,i,j) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j)
  `2 < s & s < G*(1,j+1)`2 } by A1,A3,Th26;
  G*(i,j) = |[r1,s1]| & G*(i+1,j+1) = |[r2,s2]| by EUCLID:53;
  then G*(i,j)+G*(i+1,j+1) = |[r1+r2,s1+s2]| by EUCLID:56;
  then
A9: 1/2*(G*(i,j)+G*(i+1,j+1)) = |[1/2*(r1+r2),1/2*(s1+s2)]| by EUCLID:58;
  i <= i+1 by NAT_1:11;
  then
A10: i <= len G by A2,XXREAL_0:2;
  then
A11: 1 <= len G by A1,XXREAL_0:2;
  j <= j+1 by NAT_1:11;
  then
A12: j <= width G by A4,XXREAL_0:2;
  then
A13: 1 <= width G by A3,XXREAL_0:2;
A14: G*(i,1)`1 = r1 by A1,A3,A10,A12,GOBOARD5:2;
  G*(1,j)`2 = s1 by A1,A3,A10,A12,GOBOARD5:1;
  then
A15: s1 < s2 by A3,A4,A7,A11,A5,GOBOARD5:4;
  then s1+s1 < s1+s2 by XREAL_1:6;
  then 1/2*(s1+s1) < 1/2*(s1+s2) by XREAL_1:68;
  then
A16: G*(1,j)`2 < 1/2*(s1+s2) by A1,A3,A10,A12,GOBOARD5:1;
A17: i < i+1 by XREAL_1:29;
  G*(i+1,1)`1 = r2 by A2,A4,A6,GOBOARD5:2;
  then
A18: r1 < r2 by A1,A2,A14,A13,A17,GOBOARD5:3;
  then r1+r2 < r2+r2 by XREAL_1:6;
  then 1/2*(r1+r2) < 1/2*(r2+r2) by XREAL_1:68;
  then
A19: 1/2*(r1+r2) < G*(i+1,1)`1 by A2,A4,A6,GOBOARD5:2;
  s1+s2 < s2+s2 by A15,XREAL_1:6;
  then 1/2*(s1+s2) < 1/2*(s2+s2) by XREAL_1:68;
  then
A20: 1/2*(s1+s2) < G*(1,j+1)`2 by A2,A4,A6,GOBOARD5:1;
  r1+r1 < r1+r2 by A18,XREAL_1:6;
  then 1/2*(r1+r1) < 1/2*(r1+r2) by XREAL_1:68;
  hence thesis by A9,A14,A19,A16,A20,A8;
end;

theorem Th32:
  1 <= i & i+1 <= len G implies 1/2*(G*(i,width G)+G*(i+1,width G)
  )+|[0,1]| in Int cell(G,i,width G)
proof
  assume that
A1: 1 <= i and
A2: i+1 <= len G;
  set r1 = G*(i,width G)`1, s1 = G*(i,width G)`2, r2 = G*(i+1,width G)`1;
  width G <> 0 by MATRIX_0:def 10;
  then
A3: 1 <= width G by NAT_1:14;
  i < len G by A2,NAT_1:13;
  then
A4: Int cell(G,i,width G) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & G
  * (1,width G)`2 < s } by A1,Th25;
  width G <> 0 by MATRIX_0:def 10;
  then
A5: 1 <= width G by NAT_1:14;
  i < i+1 by XREAL_1:29;
  then
A6: r1 < r2 by A1,A2,A5,GOBOARD5:3;
  then r1+r1 < r1+r2 by XREAL_1:6;
  then
A7: 1/2*(r1+r1) < 1/2*(r1+r2) by XREAL_1:68;
A8: i < len G by A2,NAT_1:13;
  then
A9: G*(1,width G)`2 = s1 by A1,A3,GOBOARD5:1;
  then
A10: G*(1,width G)`2 < s1+1 by XREAL_1:29;
A11: 1 <= i+1 by NAT_1:11;
  then G*(1,width G)`2 = G*(i+1,width G)`2 by A2,A3,GOBOARD5:1;
  then G*(i,width G) = |[r1,s1]| & G*(i+1,width G) = |[r2,s1]| by A9,EUCLID:53;
  then 1/2*(s1+s1) = s1 & G*(i,width G)+G*(i+1,width G) = |[r1+r2,s1+s1]| by
EUCLID:56;
  then 1/2*(G*(i,width G)+G*(i+1,width G))= |[1/2*(r1+r2),s1]| by EUCLID:58;
  then
A12: 1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]| = |[1/2*(r1+r2)+0,s1+1 ]|
  by EUCLID:56;
  r1+r2 < r2+r2 by A6,XREAL_1:6;
  then 1/2*(r1+r2) < 1/2*(r2+r2) by XREAL_1:68;
  then
A13: 1/2*(r1+r2) < G*(i+1,1)`1 by A2,A11,A3,GOBOARD5:2;
  G*(i,1)`1 = r1 by A1,A8,A3,GOBOARD5:2;
  hence thesis by A12,A7,A13,A10,A4;
end;

theorem Th33:
  1 <= i & i+1 <= len G implies 1/2*(G*(i,1)+G*(i+1,1))-|[0,1]| in
  Int cell(G,i,0)
proof
  assume that
A1: 1 <= i and
A2: i+1 <= len G;
  set r1 = G*(i,1)`1, s1 = G*(i,1)`2, r2 = G*(i+1,1)`1;
  width G <> 0 by MATRIX_0:def 10;
  then
A3: 1 <= width G by NAT_1:14;
  width G <> 0 by MATRIX_0:def 10;
  then
A4: 1 <= width G by NAT_1:14;
  i < i+1 by XREAL_1:29;
  then
A5: r1 < r2 by A1,A2,A4,GOBOARD5:3;
  then r1+r1 < r1+r2 by XREAL_1:6;
  then
A6: 1/2*(r1+r1) < 1/2*(r1+r2) by XREAL_1:68;
  i < len G by A2,NAT_1:13;
  then
A7: G*(1,1)`2 = s1 by A1,A3,GOBOARD5:1;
  then s1 < G*(1,1)`2+1 by XREAL_1:29;
  then
A8: s1-1 < G*(1,1)`2 by XREAL_1:19;
  1 <= i+1 by NAT_1:11;
  then G*(1,1)`2 = G*(i+1,1)`2 by A2,A3,GOBOARD5:1;
  then G*(i,1) = |[r1,s1]| & G*(i+1,1) = |[r2,s1]| by A7,EUCLID:53;
  then 1/2*(s1+s1) = s1 & G*(i,1)+G*(i+1,1) = |[r1+r2,s1+s1]| by EUCLID:56;
  then 1/2*(G*(i,1)+G*(i+1,1))= |[1/2*(r1+r2),s1]| by EUCLID:58;
  then
A9: 1/2*(G*(i,1)+G*(i+1,1))-|[0,1]| = |[1/2*(r1+r2)-0,s1-1]| by EUCLID:62
    .= |[1/2*(r1+r2),s1-1]|;
  r1+r2 < r2+r2 by A5,XREAL_1:6;
  then
A10: 1/2*(r1+r2) < 1/2*(r2+r2) by XREAL_1:68;
  i < len G by A2,NAT_1:13;
  then
  Int cell(G,i,0) = { |[r,s]| : G*(i,1)`1 < r & r < G*(i+1,1)`1 & s < G*(
  1,1)`2 } by A1,Th24;
  hence thesis by A9,A6,A10,A8;
end;

theorem Th34:
  1 <= j & j+1 <= width G implies 1/2*(G*(len G,j)+G*(len G,j+1))+
  |[1,0]| in Int cell(G,len G,j)
proof
  assume that
A1: 1 <= j and
A2: j+1 <= width G;
  set s1 = G*(len G,j)`2, r1 = G*(len G,j)`1, s2 = G*(len G,j+1)`2;
  len G <> 0 by MATRIX_0:def 10;
  then
A3: 1 <= len G by NAT_1:14;
  j < width G by A2,NAT_1:13;
  then
A4: Int cell(G,len G,j) = { |[r,s]| : G*(len G,1)`1 < r & G*(1,j)`2 < s & s
  < G* (1,j+1)`2 } by A1,Th23;
  len G <> 0 by MATRIX_0:def 10;
  then
A5: 1 <= len G by NAT_1:14;
  j < j+1 by XREAL_1:29;
  then
A6: s1 < s2 by A1,A2,A5,GOBOARD5:4;
  then s1+s1 < s1+s2 by XREAL_1:6;
  then
A7: 1/2*(s1+s1) < 1/2*(s1+s2) by XREAL_1:68;
A8: j < width G by A2,NAT_1:13;
  then
A9: G*(len G,1)`1 = r1 by A1,A3,GOBOARD5:2;
  then
A10: G*(len G,1)`1 < r1+1 by XREAL_1:29;
A11: 1 <= j+1 by NAT_1:11;
  then G*(len G,1)`1 = G*(len G,j+1)`1 by A2,A3,GOBOARD5:2;
  then G*(len G,j) = |[r1,s1]| & G*(len G,j+1) = |[r1,s2]| by A9,EUCLID:53;
  then 1/2*(r1+r1) = r1 & G*(len G,j)+G*(len G,j+1) = |[r1+r1,s1+s2]| by
EUCLID:56;
  then 1/2*(G*(len G,j)+G*(len G,j+1))= |[r1,1/2*(s1+s2)]| by EUCLID:58;
  then
A12: 1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]| = |[r1+1,1/2*(s1+s2)+0]| by
EUCLID:56;
  s1+s2 < s2+s2 by A6,XREAL_1:6;
  then 1/2*(s1+s2) < 1/2*(s2+s2) by XREAL_1:68;
  then
A13: 1/2*(s1+s2) < G*(1,j+1)`2 by A2,A11,A3,GOBOARD5:1;
  G*(1,j)`2 = s1 by A1,A8,A3,GOBOARD5:1;
  hence thesis by A12,A7,A13,A10,A4;
end;

theorem Th35:
  1 <= j & j+1 <= width G implies 1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|
  in Int cell(G,0,j)
proof
  assume that
A1: 1 <= j and
A2: j+1 <= width G;
  set s1 = G*(1,j)`2, r1 = G*(1,j)`1, s2 = G*(1,j+1)`2;
  len G <> 0 by MATRIX_0:def 10;
  then
A3: 1 <= len G by NAT_1:14;
  len G <> 0 by MATRIX_0:def 10;
  then
A4: 1 <= len G by NAT_1:14;
  j < j+1 by XREAL_1:29;
  then
A5: s1 < s2 by A1,A2,A4,GOBOARD5:4;
  then s1+s1 < s1+s2 by XREAL_1:6;
  then
A6: 1/2*(s1+s1) < 1/2*(s1+s2) by XREAL_1:68;
  j < width G by A2,NAT_1:13;
  then
A7: G*(1,1)`1 = r1 by A1,A3,GOBOARD5:2;
  then r1 < G*(1,1)`1+1 by XREAL_1:29;
  then
A8: r1-1 < G*(1,1)`1 by XREAL_1:19;
  1 <= j+1 by NAT_1:11;
  then G*(1,1)`1 = G*(1,j+1)`1 by A2,A3,GOBOARD5:2;
  then G*(1,j) = |[r1,s1]| & G*(1,j+1) = |[r1,s2]| by A7,EUCLID:53;
  then 1/2*(r1+r1) = r1 & G*(1,j)+G*(1,j+1) = |[r1+r1,s1+s2]| by EUCLID:56;
  then 1/2*(G*(1,j)+G*(1,j+1))= |[r1,1/2*(s1+s2)]| by EUCLID:58;
  then
A9: 1/2*(G*(1,j)+G*(1,j+1))-|[1,0]| = |[r1-1,1/2*(s1+s2)-0]| by EUCLID:62
    .= |[r1-1,1/2*(s1+s2)]|;
  s1+s2 < s2+s2 by A5,XREAL_1:6;
  then
A10: 1/2*(s1+s2) < 1/2*(s2+s2) by XREAL_1:68;
  j < width G by A2,NAT_1:13;
  then
  Int cell(G,0,j) = { |[r,s]| : r < G*(1,1)`1 & G*(1,j)`2 < s & s < G*(1,
  j+1)`2 } by A1,Th20;
  hence thesis by A9,A6,A10,A8;
end;

theorem Th36:
  G*(1,1)-|[1,1]| in Int cell(G,0,0)
proof
  set s1 = G*(1,1)`2, r1 = G*(1,1)`1;
  G*(1,1) = |[r1,s1]| by EUCLID:53;
  then
A1: G*(1,1)-|[1,1]| = |[r1-1,s1-1]| by EUCLID:62;
  s1 < G*(1,1)`2+1 by XREAL_1:29;
  then
A2: s1-1 < G*(1,1)`2 by XREAL_1:19;
  r1 < G*(1,1)`1+1 by XREAL_1:29;
  then
A3: r1-1 < G*(1,1)`1 by XREAL_1:19;
  Int cell(G,0,0) = { |[r,s]| : r < G*(1,1)`1 & s < G*(1,1)`2 } by Th18;
  hence thesis by A1,A2,A3;
end;

theorem Th37:
  G*(len G,width G)+|[1,1]| in Int cell(G,len G,width G)
proof
  set s1 = G*(len G,width G)`2, r1 = G*(len G,width G)`1;
  len G <> 0 by MATRIX_0:def 10;
  then
A1: 1 <= len G by NAT_1:14;
  width G <> 0 by MATRIX_0:def 10;
  then
A2: 1 <= width G by NAT_1:14;
  then G*(len G,1)`1 = r1 by A1,GOBOARD5:2;
  then
A3: r1+1 > G*(len G,1)`1 by XREAL_1:29;
  G*(len G,width G) = |[r1,s1]| by EUCLID:53;
  then
A4: G*(len G,width G)+|[1,1]| = |[r1+1,s1+1]| by EUCLID:56;
  G*(1,width G)`2 = s1 by A2,A1,GOBOARD5:1;
  then
A5: s1+1 > G*(1,width G)`2 by XREAL_1:29;
  Int cell(G,len G,width G) = { |[r,s]| : G*(len G,1)`1 < r & G*(1,width
  G)`2 < s } by Th22;
  hence thesis by A4,A5,A3;
end;

theorem Th38:
  G*(1,width G)+|[-1,1]| in Int cell(G,0,width G)
proof
  set s1 = G*(1,width G)`2, r1 = G*(1,width G)`1;
  len G <> 0 by MATRIX_0:def 10;
  then
A1: 1 <= len G by NAT_1:14;
  width G <> 0 by MATRIX_0:def 10;
  then 1 <= width G by NAT_1:14;
  then G*(1,1)`1 = r1 by A1,GOBOARD5:2;
  then r1 < G*(1,1)`1+1 by XREAL_1:29;
  then
A2: s1+1 > G*(1,width G)`2 & r1-1 < G*(1,1)`1 by XREAL_1:19,29;
  G*(1,width G) = |[r1,s1]| by EUCLID:53;
  then
A3: G*(1,width G)+|[-1,1]| = |[r1+-1,s1+1]| by EUCLID:56
    .= |[r1-1,s1+1]|;
  Int cell(G,0,width G) = { |[r,s]| : r < G*(1,1)`1 & G*(1,width G)`2 < s
  } by Th19;
  hence thesis by A3,A2;
end;

theorem Th39:
  G*(len G,1)+|[1,-1]| in Int cell(G,len G,0)
proof
  set s1 = G*(len G,1)`2, r1 = G*(len G,1)`1;
A1: r1+1 > G*(len G,1)`1 by XREAL_1:29;
  len G <> 0 by MATRIX_0:def 10;
  then
A2: 1 <= len G by NAT_1:14;
  width G <> 0 by MATRIX_0:def 10;
  then 1 <= width G by NAT_1:14;
  then G*(1,1)`2 = s1 by A2,GOBOARD5:1;
  then s1 < G*(1,1)`2+1 by XREAL_1:29;
  then
A3: s1-1 < G*(1,1)`2 by XREAL_1:19;
  G*(len G,1) = |[r1,s1]| by EUCLID:53;
  then
A4: G*(len G,1)+|[1,-1]| = |[r1+1,s1+-1]| by EUCLID:56
    .= |[r1+1,s1-1]|;
  Int cell(G,len G,0) = { |[r,s]| : G*(len G,1)`1 < r & s < G* (1,1)`2 }
  by Th21;
  hence thesis by A4,A3,A1;
end;

theorem Th40:
  1 <= i & i < len G & 1 <= j & j < width G implies LSeg(1/2*(G*(i
,j)+G*(i+1,j+1)),1/2*(G*(i,j)+G*(i,j+1))) c= Int cell(G,i,j) \/ { 1/2*(G*(i,j)+
  G*(i,j+1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 <= j and
A4: j < width G;
  let x be object;
  assume
A5: x in LSeg(1/2*(G*(i,j)+G*(i+1,j+1)),1/2*(G*(i,j)+G*(i,j+1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A6: p = (1-r)*(1/2*(G*(i,j)+G*(i+1,j+1)))+r*(1/2*(G*(i,j)+G*(i,j+1))) and
A7: 0<=r and
A8: r<=1 by A5;
  now
    per cases by A8,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i,j)+G*(i,j+1))) by A6,RLVECT_1:10

        .= 1*(1/2*(G*(i,j)+G*(i,j+1))) by RLVECT_1:4
        .= 1/2*(G*(i,j)+G*(i,j+1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i,j)+G*(i,j+1)) } by TARSKI:def 1;
    end;
    case
A9:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r1 = G*(i,1)`1, r2 = G*(i+1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A10:  r3*(s1+s1)+s3*(s1+s1) = s1;
      0 <> len G by MATRIX_0:def 10;
      then
A11:  1 <= len G by NAT_1:14;
A12:  j+1 <= width G by A4,NAT_1:13;
      j < j+1 by XREAL_1:29;
      then
A13:  s1 < s2 by A3,A12,A11,GOBOARD5:4;
      then
A14:  s1+s1 < s1+s2 by XREAL_1:6;
      then
A15:  s3*(s1+s1) <= s3*(s1+s2) by A7,XREAL_1:64;
      1 - r > 0 by A9,XREAL_1:50;
      then
A16:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(s1+s1) < r3*(s1+s2) by A14,XREAL_1:68;
      then
A17:  s1 < r3*(s1+s2)+s3*(s1+s2) by A15,A10,XREAL_1:8;
A18:  s1+s2 < s2+s2 by A13,XREAL_1:6;
      then
A19:  s3*(s1+s2) <= s3*(s2+s2) by A7,XREAL_1:64;
      0 <> width G by MATRIX_0:def 10;
      then
A20:  1 <= width G by NAT_1:14;
A21:  1 <= i+1 by A1,NAT_1:13;
A22:  Int cell(G,i,j) = { |[r9,s9]| : r1 < r9 & r9 < r2 & s1 < s9 & s9 <
      s2 } by A1,A2,A3,A4,Th26;
A23:  1 <= j+1 by A3,NAT_1:13;
A24:  G*(i,j+1) = |[G*(i,j+1)`1,G*(i,j+1)`2]| by EUCLID:53
        .= |[r1,G*(i,j+1)`2]| by A1,A2,A23,A12,GOBOARD5:2
        .= |[r1,s2]| by A1,A2,A23,A12,GOBOARD5:1;
A25:  r3*(s2+s2)+s3*(s2+s2) = s2;
      r3*(s1+s2) < r3*(s2+s2) by A16,A18,XREAL_1:68;
      then
A26:  r3*(s1+s2)+s3*(s1+s2) < s2 by A19,A25,XREAL_1:8;
A27:  i+1 <= len G by A2,NAT_1:13;
      i < i+1 by XREAL_1:29;
      then
A28:  r1 < r2 by A1,A27,A20,GOBOARD5:3;
      then r1+r1 < r2+r2 by XREAL_1:8;
      then
A29:  s3*(r1+r1) <= s3*(r2+r2) by A7,XREAL_1:64;
      r1+r2 < r2+r2 by A28,XREAL_1:6;
      then
A30:  r3*(r1+r2) < r3*(r2+r2) by A16,XREAL_1:68;
      r3*(r2+r2)+s3*(r2+r2) = r2;
      then
A31:  r3*(r1+r2)+s3*(r1+r1) < r2 by A30,A29,XREAL_1:8;
A32:  G*(i,j) = |[G*(i,j)`1,G*(i,j)`2]| by EUCLID:53
        .= |[r1,G*(i,j)`2]| by A1,A2,A3,A4,GOBOARD5:2
        .= |[r1,s1]| by A1,A2,A3,A4,GOBOARD5:1;
A33:  G*(i+1,j+1) = |[G*(i+1,j+1)`1,G*(i+1,j+1)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j+1)`2]| by A23,A12,A21,A27,GOBOARD5:2
        .= |[r2,s2]| by A23,A12,A21,A27,GOBOARD5:1;
A34:  r3*(r1+r1)+s3*(r1+r1) = r1;
      r1+r1 < r1+r2 by A28,XREAL_1:6;
      then r3*(r1+r1) < r3*(r1+r2) by A16,XREAL_1:68;
      then
A35:  r1 < r3*(r1+r2)+s3*(r1+r1) by A34,XREAL_1:6;
      p = r3*(G*(i,j)+G*(i+1,j+1))+r*(1/2*(G*(i,j)+G* (i,j+1))) by A6,
RLVECT_1:def 7
        .= r3*(G*(i,j)+G*(i+1,j+1))+s3*(G*(i,j)+G*(i,j+1)) by RLVECT_1:def 7
        .= r3*|[r1+r2,s1+s2]|+s3*(G*(i,j)+G*(i,j+1)) by A32,A33,EUCLID:56
        .= r3*|[r1+r2,s1+s2]|+s3*|[r1+r1,s1+s2]| by A32,A24,EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s2)]|+s3*|[r1+r1,s1+s2]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s1+s2)]|+|[s3*(r1+r1),s3*(s1+s2)]| by EUCLID:58
        .= |[r3*(r1+r2)+s3*(r1+r1),r3*(s1+s2)+s3*(s1+s2)]| by EUCLID:56;
      hence p in Int cell(G,i,j) by A35,A31,A17,A26,A22;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th41:
  1 <= i & i < len G & 1 <= j & j < width G implies LSeg(1/2*(G*(i
,j)+G*(i+1,j+1)),1/2*(G*(i,j+1)+G*(i+1,j+1))) c= Int cell(G,i,j) \/ { 1/2*(G*(i
  ,j+1)+G*(i+1,j+1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 <= j and
A4: j < width G;
  let x be object;
  assume
A5: x in LSeg(1/2*(G*(i,j)+G*(i+1,j+1)),1/2*(G*(i,j+1)+G*(i+1,j+1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A6: p = (1-r)*(1/2*(G*(i,j)+G*(i+1,j+1)))+r*(1/2*(G*(i,j+1)+G*(i+1,j+1)) ) and
A7: 0<=r and
A8: r<=1 by A5;
  now
    per cases by A8,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i,j+1)+G*(i+1,j+1))) by A6,RLVECT_1:10

        .= 1*(1/2*(G*(i,j+1)+G*(i+1,j+1))) by RLVECT_1:4
        .= 1/2*(G*(i,j+1)+G*(i+1,j+1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i,j+1)+G*(i+1,j+1)) } by TARSKI:def 1;
    end;
    case
A9:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r1 = G*(i,1)`1, r2 = G*(i+1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A10:  r3*(r1+r1)+s3*(r1+r1) = r1;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
A12:  i+1 <= len G by A2,NAT_1:13;
      i < i+1 by XREAL_1:29;
      then
A13:  r1 < r2 by A1,A12,A11,GOBOARD5:3;
      then
A14:  r1+r1 < r1+r2 by XREAL_1:6;
      then
A15:  s3*(r1+r1) <= s3*(r1+r2) by A7,XREAL_1:64;
      1 - r > 0 by A9,XREAL_1:50;
      then
A16:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(r1+r1) < r3*(r1+r2) by A14,XREAL_1:68;
      then
A17:  r1 < r3*(r1+r2)+s3*(r1+r2) by A15,A10,XREAL_1:8;
      0 <> len G by MATRIX_0:def 10;
      then
A18:  1 <= len G by NAT_1:14;
A19:  1 <= i+1 by A1,NAT_1:13;
      r1+r2 < r2+r2 by A13,XREAL_1:8;
      then
A20:  s3*(r1+r2) <= s3*(r2+r2) by A7,XREAL_1:64;
A21:  j+1 <= width G by A4,NAT_1:13;
      r1+r2 < r2+r2 by A13,XREAL_1:6;
      then
A22:  r3*(r1+r2) < r3*(r2+r2) by A16,XREAL_1:68;
      r3*(r2+r2)+s3*(r2+r2) = r2;
      then
A23:  r3*(r1+r2)+s3*(r1+r2) < r2 by A22,A20,XREAL_1:8;
A24:  Int cell(G,i,j) = { |[r9,s9]| : r1 < r9 & r9 < r2 & s1 < s9 & s9 <
      s2 } by A1,A2,A3,A4,Th26;
A25:  1 <= j+1 by A3,NAT_1:13;
      j < j+1 by XREAL_1:29;
      then
A26:  s1 < s2 by A3,A21,A18,GOBOARD5:4;
      then
A27:  s1+s1 < s1+s2 by XREAL_1:6;
A28:  G*(i+1,j+1) = |[G*(i+1,j+1)`1,G*(i+1,j+1)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j+1)`2]| by A25,A21,A19,A12,GOBOARD5:2
        .= |[r2,s2]| by A25,A21,A19,A12,GOBOARD5:1;
      s1+s2 < s2+s2 by A26,XREAL_1:6;
      then s1+s1 < s2+s2 by A27,XXREAL_0:2;
      then
A29:  s3*(s1+s1) <= s3*(s2+s2) by A7,XREAL_1:64;
A30:  G*(i,j) = |[G*(i,j)`1,G*(i,j)`2]| by EUCLID:53
        .= |[r1,G*(i,j)`2]| by A1,A2,A3,A4,GOBOARD5:2
        .= |[r1,s1]| by A1,A2,A3,A4,GOBOARD5:1;
A31:  r3*(s2+s2)+s3*(s2+s2) = s2;
A32:  G*(i,j+1) = |[G*(i,j+1)`1,G*(i,j+1)`2]| by EUCLID:53
        .= |[r1,G*(i,j+1)`2]| by A1,A2,A25,A21,GOBOARD5:2
        .= |[r1,s2]| by A1,A2,A25,A21,GOBOARD5:1;
A33:  r3*(s1+s1)+s3*(s1+s1) = s1;
      s1+s2 < s2+s2 by A26,XREAL_1:6;
      then r3*(s1+s2) < r3*(s2+s2) by A16,XREAL_1:68;
      then
A34:  r3*(s1+s2)+s3*(s2+s2) < s2 by A31,XREAL_1:8;
      r3*(s1+s1) < r3*(s1+s2) by A16,A27,XREAL_1:68;
      then
A35:  s1 < r3*(s1+s2)+s3*(s2+s2) by A29,A33,XREAL_1:8;
      p = r3*(G*(i,j)+G*(i+1,j+1))+r*(1/2*(G*(i,j+1)+G*(i+1,j+1))) by A6,
RLVECT_1:def 7
        .= r3*(G*(i,j)+G*(i+1,j+1))+s3*(G*(i,j+1)+G*(i+1,j+1)) by
RLVECT_1:def 7
        .= r3*|[r1+r2,s1+s2]|+s3*(G*(i,j+1)+G*(i+1,j+1)) by A30,A28,EUCLID:56
        .= r3*|[r1+r2,s1+s2]|+s3*|[r1+r2,s2+s2]| by A28,A32,EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s2)]|+s3*|[r1+r2,s2+s2]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s1+s2)]|+|[s3*(r1+r2),s3*(s2+s2)]| by EUCLID:58
        .= |[r3*(r1+r2)+s3*(r1+r2),r3*(s1+s2)+s3*(s2+s2)]| by EUCLID:56;
      hence p in Int cell(G,i,j) by A17,A23,A35,A34,A24;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th42:
  1 <= i & i < len G & 1 <= j & j < width G implies LSeg(1/2*(G*(i
,j)+G*(i+1,j+1)),1/2*(G*(i+1,j)+G*(i+1,j+1))) c= Int cell(G,i,j) \/ { 1/2*(G*(i
  +1,j)+G*(i+1,j+1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 <= j and
A4: j < width G;
  let x be object;
  assume
A5: x in LSeg(1/2*(G*(i,j)+G*(i+1,j+1)),1/2*(G*(i+1,j)+G*(i+1,j+1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A6: p = (1-r)*(1/2*(G*(i,j)+G*(i+1,j+1)))+r*(1/2*(G*(i+1,j)+G*(i+1,j+1)) ) and
A7: 0<=r and
A8: r<=1 by A5;
  now
    per cases by A8,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i+1,j)+G*(i+1,j+1))) by A6,RLVECT_1:10

        .= 1*(1/2*(G*(i+1,j)+G*(i+1,j+1))) by RLVECT_1:4
        .= 1/2*(G*(i+1,j)+G*(i+1,j+1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i+1,j)+G*(i+1,j+1)) } by TARSKI:def 1;
    end;
    case
A9:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r1 = G*(i,1)`1, r2 = G*(i+1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A10:  r3*(r1+r1)+s3*(r1+r1) = r1;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
A12:  i+1 <= len G by A2,NAT_1:13;
      i < i+1 by XREAL_1:29;
      then
A13:  r1 < r2 by A1,A12,A11,GOBOARD5:3;
      then
A14:  r1+r1 < r1+r2 by XREAL_1:6;
      r1+r2 < r2+r2 by A13,XREAL_1:6;
      then r1+r1 < r2+r2 by A14,XXREAL_0:2;
      then
A15:  s3*(r1+r1) <= s3*(r2+r2) by A7,XREAL_1:64;
      1 - r > 0 by A9,XREAL_1:50;
      then
A16:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(r1+r1) < r3*(r1+r2) by A14,XREAL_1:68;
      then
A17:  r1 < r3*(r1+r2)+s3*(r2+r2) by A15,A10,XREAL_1:8;
      0 <> len G by MATRIX_0:def 10;
      then
A18:  1 <= len G by NAT_1:14;
A19:  1 <= j+1 by A3,NAT_1:13;
A20:  Int cell(G,i,j) = { |[r9,s9]| : r1 < r9 & r9 < r2 & s1 < s9 & s9 <
      s2 } by A1,A2,A3,A4,Th26;
A21:  r3*(s2+s2)+s3*(s2+s2) = s2;
A22:  G*(i,j) = |[G*(i,j)`1,G*(i,j)`2]| by EUCLID:53
        .= |[r1,G*(i,j)`2]| by A1,A2,A3,A4,GOBOARD5:2
        .= |[r1,s1]| by A1,A2,A3,A4,GOBOARD5:1;
A23:  r3*(s1+s1)+s3*(s1+s1) = s1;
A24:  1 <= i+1 by A1,NAT_1:13;
A25:  G*(i+1,j) = |[G*(i+1,j)`1,G*(i+1,j)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j)`2]| by A3,A4,A24,A12,GOBOARD5:2
        .= |[r2,s1]| by A3,A4,A24,A12,GOBOARD5:1;
A26:  r3*(r2+r2)+s3*(r2+r2) = r2;
      r1+r2 < r2+r2 by A13,XREAL_1:6;
      then r3*(r1+r2) < r3*(r2+r2) by A16,XREAL_1:68;
      then
A27:  r3*(r1+r2)+s3*(r2+r2) < r2 by A26,XREAL_1:8;
A28:  j+1 <= width G by A4,NAT_1:13;
A29:  G*(i+1,j+1) = |[G*(i+1,j+1)`1,G*(i+1,j+1)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j+1)`2]| by A19,A28,A24,A12,GOBOARD5:2
        .= |[r2,s2]| by A19,A28,A24,A12,GOBOARD5:1;
      j < j+1 by XREAL_1:29;
      then
A30:  s1 < s2 by A3,A28,A18,GOBOARD5:4;
      then
A31:  s1+s1 < s1+s2 by XREAL_1:6;
      then
A32:  s3*(s1+s1) <= s3*(s1+s2) by A7,XREAL_1:64;
      r3*(s1+s1) < r3*(s1+s2) by A16,A31,XREAL_1:68;
      then
A33:  s1 < r3*(s1+s2)+s3*(s1+s2) by A32,A23,XREAL_1:8;
A34:  s1+s2 < s2+s2 by A30,XREAL_1:6;
      then
A35:  s3*(s1+s2) <= s3*(s2+s2) by A7,XREAL_1:64;
      r3*(s1+s2) < r3*(s2+s2) by A16,A34,XREAL_1:68;
      then
A36:  r3*(s1+s2)+s3*(s1+s2) < s2 by A35,A21,XREAL_1:8;
      p = r3*(G*(i,j)+G*(i+1,j+1))+r*(1/2*(G*(i+1,j)+G*(i+1,j+1))) by A6,
RLVECT_1:def 7
        .= r3*(G*(i,j)+G*(i+1,j+1))+s3*(G*(i+1,j)+G*(i+1,j+1)) by
RLVECT_1:def 7
        .= r3*|[r1+r2,s1+s2]|+s3*(G*(i+1,j)+G*(i+1,j+1)) by A22,A29,EUCLID:56
        .= r3*|[r1+r2,s1+s2]|+s3*|[r2+r2,s1+s2]| by A29,A25,EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s2)]|+s3*|[r2+r2,s1+s2]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s1+s2)]|+|[s3*(r2+r2),s3*(s1+s2)]| by EUCLID:58
        .= |[r3*(r1+r2)+s3*(r2+r2),r3*(s1+s2)+s3*(s1+s2)]| by EUCLID:56;
      hence p in Int cell(G,i,j) by A17,A27,A33,A36,A20;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th43:
  1 <= i & i < len G & 1 <= j & j < width G implies LSeg(1/2*(G*(i
,j)+G*(i+1,j+1)),1/2*(G*(i,j)+G*(i+1,j))) c= Int cell(G,i,j) \/ { 1/2*(G*(i,j)+
  G*(i+1,j)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 <= j and
A4: j < width G;
  let x be object;
  assume
A5: x in LSeg(1/2*(G*(i,j)+G*(i+1,j+1)),1/2*(G*(i,j)+G*(i+1,j)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A6: p = (1-r)*(1/2*(G*(i,j)+G*(i+1,j+1)))+r*(1/2*(G*(i,j)+G*(i+1,j))) and
A7: 0<=r and
A8: r<=1 by A5;
  now
    per cases by A8,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i,j)+G*(i+1,j))) by A6,RLVECT_1:10

        .= 1*(1/2*(G*(i,j)+G*(i+1,j))) by RLVECT_1:4
        .= 1/2*(G*(i,j)+G*(i+1,j)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i,j)+G*(i+1,j)) } by TARSKI:def 1;
    end;
    case
A9:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r1 = G*(i,1)`1, r2 = G*(i+1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A10:  r3*(r1+r1)+s3*(r1+r1) = r1;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
A12:  i+1 <= len G by A2,NAT_1:13;
      i < i+1 by XREAL_1:29;
      then
A13:  r1 < r2 by A1,A12,A11,GOBOARD5:3;
      then
A14:  r1+r1 < r1+r2 by XREAL_1:6;
      then
A15:  s3*(r1+r1) <= s3*(r1+r2) by A7,XREAL_1:64;
      r1+r2 < r2+r2 by A13,XREAL_1:8;
      then
A16:  s3*(r1+r2) <= s3*(r2+r2) by A7,XREAL_1:64;
A17:  1 <= i+1 by A1,NAT_1:13;
      1 - r > 0 by A9,XREAL_1:50;
      then
A18:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(r1+r1) < r3*(r1+r2) by A14,XREAL_1:68;
      then
A19:  r1 < r3*(r1+r2)+s3*(r1+r2) by A15,A10,XREAL_1:8;
      r1+r2 < r2+r2 by A13,XREAL_1:6;
      then
A20:  r3*(r1+r2) < r3*(r2+r2) by A18,XREAL_1:68;
      r3*(r2+r2)+s3*(r2+r2) = r2;
      then
A21:  r3*(r1+r2)+s3*(r1+r2) < r2 by A20,A16,XREAL_1:8;
A22:  Int cell(G,i,j) = { |[r9,s9]| : r1 < r9 & r9 < r2 & s1 < s9 & s9 <
      s2 } by A1,A2,A3,A4,Th26;
A23:  j+1 <= width G by A4,NAT_1:13;
A24:  G*(i+1,j) = |[G*(i+1,j)`1,G*(i+1,j)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j)`2]| by A3,A4,A17,A12,GOBOARD5:2
        .= |[r2,s1]| by A3,A4,A17,A12,GOBOARD5:1;
A25:  1 <= j+1 by A3,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A26:  1 <= len G by NAT_1:14;
A27:  G*(i,j) = |[G*(i,j)`1,G*(i,j)`2]| by EUCLID:53
        .= |[r1,G*(i,j)`2]| by A1,A2,A3,A4,GOBOARD5:2
        .= |[r1,s1]| by A1,A2,A3,A4,GOBOARD5:1;
      j < j+1 by XREAL_1:29;
      then
A28:  s1 < s2 by A3,A23,A26,GOBOARD5:4;
      then s1+s2 < s2+s2 by XREAL_1:6;
      then
A29:  r3*(s1+s2) < r3*(s2+s2) by A18,XREAL_1:68;
A30:  G*(i+1,j+1) = |[G*(i+1,j+1)`1,G*(i+1,j+1)`2]| by EUCLID:53
        .= |[r2,G*(i+1,j+1)`2]| by A25,A23,A17,A12,GOBOARD5:2
        .= |[r2,s2]| by A25,A23,A17,A12,GOBOARD5:1;
A31:  r3*(s1+s1)+s3*(s1+s1) = s1;
A32:  s1+s1 < s1+s2 by A28,XREAL_1:6;
      then r3*(s1+s1) < r3*(s1+s2) by A18,XREAL_1:68;
      then
A33:  s1 < r3*(s1+s2)+s3*(s1+s1) by A31,XREAL_1:8;
      s1+s2 < s2+s2 by A28,XREAL_1:6;
      then s1+s1 < s2+s2 by A32,XXREAL_0:2;
      then
A34:  s3*(s1+s1) <= s3*(s2+s2) by A7,XREAL_1:64;
      r3*(s2+s2)+s3*(s2+s2) = s2;
      then
A35:  r3*(s1+s2)+s3*(s1+s1) < s2 by A29,A34,XREAL_1:8;
      p = r3*(G*(i,j)+G*(i+1,j+1))+r*(1/2*(G*(i,j)+G* (i+1,j))) by A6,
RLVECT_1:def 7
        .= r3*(G*(i,j)+G*(i+1,j+1))+s3*(G*(i,j)+G*(i+1,j)) by RLVECT_1:def 7
        .= r3*|[r1+r2,s1+s2]|+s3*(G*(i,j)+G*(i+1,j)) by A27,A30,EUCLID:56
        .= r3*|[r1+r2,s1+s2]|+s3*|[r1+r2,s1+s1]| by A27,A24,EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s2)]|+s3*|[r1+r2,s1+s1]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s1+s2)]|+|[s3*(r1+r2),s3*(s1+s1)]| by EUCLID:58
        .= |[r3*(r1+r2)+s3*(r1+r2),r3*(s1+s2)+s3*(s1+s1)]| by EUCLID:56;
      hence p in Int cell(G,i,j) by A19,A21,A33,A35,A22;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th44:
  1 <= j & j < width G implies LSeg(1/2*(G*(1,j)+G*(1,j+1)) - |[1,
0]|,1/2*(G*(1,j)+G*(1,j+1))) c= Int cell(G,0,j) \/ { 1/2*(G*(1,j)+G*(1,j+1)) }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|,1/2*(G*(1,j)+G*(1,j+1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|)+r*(1/2*(G*(1,j)+G* (1,j+
  1))) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(1,j)+G*(1,j+1))) by A4,RLVECT_1:10

        .= 1*(1/2*(G*(1,j)+G*(1,j+1))) by RLVECT_1:4
        .= 1/2*(G*(1,j)+G*(1,j+1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(1,j)+G*(1,j+1)) } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r2 = G*(1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A8:   r3*(s1+s1)+s3*(s1+s1) = s1;
A9:   j+1 <= width G by A2,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A10:  1 <= len G by NAT_1:14;
      j < j+1 by XREAL_1:29;
      then
A11:  s1 < s2 by A1,A9,A10,GOBOARD5:4;
      then
A12:  s1+s1 < s1+s2 by XREAL_1:6;
      then
A13:  s3*(s1+s1) <= s3*(s1+s2) by A5,XREAL_1:64;
A14:  1 - r > 0 by A7,XREAL_1:50;
      then
A15:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(s1+s1) < r3*(s1+s2) by A12,XREAL_1:68;
      then
A16:  s1 < r3*(s1+s2)+s3*(s1+s2) by A13,A8,XREAL_1:8;
      r2 < r2+(1-r) by A14,XREAL_1:29;
      then
A17:  r2-(1-r) < r2 by XREAL_1:19;
A18:  1 <= j+1 by A1,NAT_1:13;
A19:  G*(1,j+1) = |[G*(1,j+1)`1,G*(1,j+1)`2]| by EUCLID:53
        .= |[r2,s2]| by A18,A9,A10,GOBOARD5:2;
A20:  s1+s2 < s2+s2 by A11,XREAL_1:6;
      then
A21:  s3*(s1+s2) <= s3*(s2+s2) by A5,XREAL_1:64;
A22:  Int cell(G,0,j) = { |[r9,s9]| : r9 < G*(1,1)`1 & G*(1,j)`2 < s9 &
      s9 < G*(1,j+1)`2 } by A1,A2,Th20;
A23:  r3*(s2+s2)+s3*(s2+s2) = s2;
      r3*(s1+s2) < r3*(s2+s2) by A15,A20,XREAL_1:68;
      then
A24:  r3*(s1+s2)+s3*(s1+s2) < s2 by A21,A23,XREAL_1:8;
A25:  G*(1,j) = |[G*(1,j)`1,G*(1,j)`2]| by EUCLID:53
        .= |[r2,s1]| by A1,A2,A10,GOBOARD5:2;
      p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1)))-(1-r)*|[1,0]| +r*(1/2*(G*(1,j)+
      G*(1,j+1))) by A4,RLVECT_1:34
        .= r3*(G*(1,j)+G*(1,j+1))-(1-r)*|[1,0]|+r*(1/2*(G*(1,j)+G*(1,j+1)))
      by RLVECT_1:def 7
        .= r3*(G*(1,j)+G*(1,j+1))-|[(1-r)*1,(1-r)*0]|+r*(1/2*(G*(1,j)+G* (1,
      j+1))) by EUCLID:58
        .= r3*(G*(1,j)+G*(1,j+1))-|[1-r,0]|+s3*(G*(1,j)+G* (1,j+1)) by
RLVECT_1:def 7
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+s3*(G*(1,j)+G*(1,j+1)) by A19,A25,
EUCLID:56
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+s3*|[r2+r2,s1+s2]| by A19,A25,EUCLID:56
        .= |[r3*(r2+r2),r3*(s1+s2)]|-|[1-r,0]|+s3*|[r2+r2,s1+s2]| by EUCLID:58
        .= |[r3*(r2+r2),r3*(s1+s2)]|-|[1-r,0]|+|[s3*(r2+r2),s3*(s1+s2)]| by
EUCLID:58
        .= |[r3*(r2+r2)-(1-r),r3*(s1+s2)-0]|+|[s3*(r2+r2),s3*(s1+s2)]| by
EUCLID:62
        .= |[r3*(r2+r2)-(1-r)+s3*(r2+r2),r3*(s1+s2)+s3*(s1+s2)]| by EUCLID:56;
      hence p in Int cell(G,0,j) by A17,A16,A24,A22;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th45:
  1 <= j & j < width G implies LSeg(1/2*(G*(len G,j)+G*(len G,j+1)
) + |[1,0]|,1/2*(G*(len G,j)+G*(len G,j+1))) c= Int cell(G,len G,j) \/ { 1/2*(G
  *(len G,j)+G*(len G,j+1)) }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|, 1/2*(G*(len G,j)+
  G*(len G,j+1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|) +r*(1/2*(G*(len
  G,j)+G*(len G,j+1))) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(len G,j)+G*(len G,j+1))) by A4,
RLVECT_1:10
        .= 1*(1/2*(G*(len G,j)+G*(len G,j+1))) by RLVECT_1:4
        .= 1/2*(G*(len G,j)+G*(len G,j+1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(len G,j)+G*(len G,j+1)) } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set r2 = G*(len G,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A8:   r3*(s1+s1)+s3*(s1+s1) = s1;
A9:   j+1 <= width G by A2,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A10:  1 <= len G by NAT_1:14;
      j < j+1 by XREAL_1:29;
      then
A11:  s1 < s2 by A1,A9,A10,GOBOARD5:4;
      then
A12:  s1+s1 < s1+s2 by XREAL_1:6;
      then
A13:  s3*(s1+s1) <= s3*(s1+s2) by A5,XREAL_1:64;
A14:  1 - r > 0 by A7,XREAL_1:50;
      then
A15:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(s1+s1) < r3*(s1+s2) by A12,XREAL_1:68;
      then
A16:  s1 < r3*(s1+s2)+s3*(s1+s2) by A13,A8,XREAL_1:8;
A17:  r2+(1-r) > r2 by A14,XREAL_1:29;
A18:  1 <= j+1 by A1,NAT_1:13;
A19:  s1+s2 < s2+s2 by A11,XREAL_1:6;
      then
A20:  s3*(s1+s2) <= s3*(s2+s2) by A5,XREAL_1:64;
A21:  Int cell(G,len G,j) = { |[r9,s9]| : G*(len G,1)`1 < r9 & G*(1,j)`2
      < s9 & s9 < G*(1,j+1)`2 } by A1,A2,Th23;
A22:  r3*(s2+s2)+s3*(s2+s2) = s2;
      r3*(s1+s2) < r3*(s2+s2) by A15,A19,XREAL_1:68;
      then
A23:  r3*(s1+s2)+s3*(s1+s2) < s2 by A20,A22,XREAL_1:8;
A24:  G*(len G,j) = |[G*(len G,j)`1,G*(len G,j)`2]| by EUCLID:53
        .= |[r2,G*(len G,j)`2]| by A1,A2,A10,GOBOARD5:2
        .= |[r2,s1]| by A1,A2,A10,GOBOARD5:1;
A25:  G*(len G,j+1) = |[G*(len G,j+1)`1,G*(len G,j+1)`2]| by EUCLID:53
        .= |[r2,G*(len G,j+1)`2]| by A18,A9,A10,GOBOARD5:2
        .= |[r2,s2]| by A18,A9,A10,GOBOARD5:1;
      p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1)))+(1-r)*|[1,0]| +r*(1/2*(
      G*(len G,j)+G*(len G,j+1))) by A4,RLVECT_1:def 5
        .= r3*(G*(len G,j)+G*(len G,j+1))+(1-r)*|[1,0]|+ r*(1/2*(G*(len G,j)
      +G*(len G,j+1))) by RLVECT_1:def 7
        .= r3*(G*(len G,j)+G*(len G,j+1))+|[(1-r)*1,(1-r)*0]|+ r*(1/2*(G*(
      len G,j)+G*(len G,j+1))) by EUCLID:58
        .= r3*(G*(len G,j)+G*(len G,j+1))+|[1-r,0]|+ s3*(G*(len G,j)+G*(len
      G,j+1)) by RLVECT_1:def 7
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+s3*(G*(len G,j)+G*(len G,j+1)) by A25
,A24,EUCLID:56
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+s3*|[r2+r2,s1+s2]| by A25,A24,EUCLID:56
        .= |[r3*(r2+r2),r3*(s1+s2)]|+|[1-r,0]|+s3*|[r2+r2,s1+s2]| by EUCLID:58
        .= |[r3*(r2+r2),r3*(s1+s2)]|+|[1-r,0]|+|[s3*(r2+r2),s3*(s1+s2)]| by
EUCLID:58
        .= |[r3*(r2+r2)+(1-r),r3*(s1+s2)+0]|+|[s3*(r2+r2),s3*(s1+s2)]| by
EUCLID:56
        .= |[r3*(r2+r2)+(1-r)+s3*(r2+r2),r3*(s1+s2)+s3*(s1+s2)]| by EUCLID:56;
      hence p in Int cell(G,len G,j) by A17,A16,A23,A21;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th46:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,1)+G*(i+1,1)) - |[0,1
  ]|,1/2*(G*(i,1)+G*(i+1,1))) c= Int cell(G,i,0) \/ { 1/2*(G*(i,1)+G*(i+1,1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|,1/2*(G*(i,1)+G*(i+1,1)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|)+r*(1/2*(G*(i,1)+G* (i+1,
  1))) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i,1)+G*(i+1,1))) by A4,RLVECT_1:10

        .= 1*(1/2*(G*(i,1)+G*(i+1,1))) by RLVECT_1:4
        .= 1/2*(G*(i,1)+G*(i+1,1)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i,1)+G*(i+1,1)) } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set s2 = G*(1,1)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A8:   r3*(r1+r1)+s3*(r1+r1) = r1;
A9:   i+1 <= len G by A2,NAT_1:13;
      0 <> width G by MATRIX_0:def 10;
      then
A10:  1 <= width G by NAT_1:14;
      i < i+1 by XREAL_1:29;
      then
A11:  r1 < r2 by A1,A9,A10,GOBOARD5:3;
      then
A12:  r1+r1 < r1+r2 by XREAL_1:6;
      then
A13:  s3*(r1+r1) <= s3*(r1+r2) by A5,XREAL_1:64;
A14:  1 - r > 0 by A7,XREAL_1:50;
      then
A15:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(r1+r1) < r3*(r1+r2) by A12,XREAL_1:68;
      then
A16:  r1 < r3*(r1+r2)+s3*(r1+r2) by A13,A8,XREAL_1:8;
      s2 < s2+(1-r) by A14,XREAL_1:29;
      then
A17:  s2-(1-r) < s2 by XREAL_1:19;
A18:  1 <= i+1 by A1,NAT_1:13;
A19:  G*(i+1,1) = |[G*(i+1,1)`1,G*(i+1,1)`2]| by EUCLID:53
        .= |[r2,s2]| by A18,A9,A10,GOBOARD5:1;
A20:  r1+r2 < r2+r2 by A11,XREAL_1:6;
      then
A21:  s3*(r1+r2) <= s3*(r2+r2) by A5,XREAL_1:64;
A22:  Int cell(G,i,0) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,1)`1 &
      s9 < G*(1,1)`2 } by A1,A2,Th24;
A23:  r3*(r2+r2)+s3*(r2+r2) = r2;
      r3*(r1+r2) < r3*(r2+r2) by A15,A20,XREAL_1:68;
      then
A24:  r3*(r1+r2)+s3*(r1+r2) < r2 by A21,A23,XREAL_1:8;
A25:  G*(i,1) = |[G*(i,1)`1,G*(i,1)`2]| by EUCLID:53
        .= |[r1,s2]| by A1,A2,A10,GOBOARD5:1;
      p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1)))-(1-r)*|[0,1]| +r*(1/2*(G*(i,1)+
      G*(i+1,1))) by A4,RLVECT_1:34
        .= r3*(G*(i,1)+G*(i+1,1))-(1-r)*|[0,1]|+r*(1/2*(G*(i,1)+G*(i+1,1)))
      by RLVECT_1:def 7
        .= r3*(G*(i,1)+G*(i+1,1))-|[(1-r)*0,(1-r)*1]|+r*(1/2*(G*(i,1)+G* (i+
      1,1))) by EUCLID:58
        .= r3*(G*(i,1)+G*(i+1,1))-|[0,1-r]|+s3*(G*(i,1)+G* (i+1,1)) by
RLVECT_1:def 7
        .= r3*|[r1+r2,s2+s2]|-|[0,1-r]|+s3*(G*(i,1)+G*(i+1,1)) by A19,A25,
EUCLID:56
        .= r3*|[r1+r2,s2+s2]|-|[0,1-r]|+s3*|[r1+r2,s2+s2]| by A19,A25,EUCLID:56
        .= |[r3*(r1+r2),r3*(s2+s2)]|-|[0,1-r]|+s3*|[r1+r2,s2+s2]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s2+s2)]|-|[0,1-r]|+|[s3*(r1+r2),s3*(s2+s2)]| by
EUCLID:58
        .= |[r3*(r1+r2)-0,r3*(s2+s2)-(1-r)]|+|[s3*(r1+r2),s3*(s2+s2)]| by
EUCLID:62
        .= |[r3*(r1+r2)+s3*(r1+r2),r3*(s2+s2)-(1-r)+s3*(s2+s2)]| by EUCLID:56;
      hence p in Int cell(G,i,0) by A17,A16,A24,A22;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th47:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,width G)+G*(i+1,width
G))+ |[0,1]|, 1/2*(G*(i,width G)+G*(i+1,width G))) c= Int cell(G,i,width G) \/
  { 1/2*(G*(i,width G)+G*(i+1,width G)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|, 1/2*(G*(i,
  width G)+G*(i+1,width G)));
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|) +r*(1/2*(G*(
  i,width G)+G*(i+1,width G))) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(1/2*(G*(i,width G)+G*(i+1,width G))) by A4,
RLVECT_1:10
        .= 1*(1/2*(G*(i,width G)+G*(i+1,width G))) by RLVECT_1:4
        .= 1/2*(G*(i,width G)+G*(i+1,width G)) by RLVECT_1:def 8;
      hence p in { 1/2*(G*(i,width G)+G*(i+1,width G)) } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2), s3 = r*(1/2);
      set s2 = G*(1,width G)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A8:   r3*(r1+r1)+s3*(r1+r1) = r1;
A9:   i+1 <= len G by A2,NAT_1:13;
      0 <> width G by MATRIX_0:def 10;
      then
A10:  1 <= width G by NAT_1:14;
      i < i+1 by XREAL_1:29;
      then
A11:  r1 < r2 by A1,A9,A10,GOBOARD5:3;
      then
A12:  r1+r1 < r1+r2 by XREAL_1:6;
      then
A13:  s3*(r1+r1) <= s3*(r1+r2) by A5,XREAL_1:64;
A14:  1 - r > 0 by A7,XREAL_1:50;
      then
A15:  r3 > (1/2)*0 by XREAL_1:68;
      then r3*(r1+r1) < r3*(r1+r2) by A12,XREAL_1:68;
      then
A16:  r1 < r3*(r1+r2)+s3*(r1+r2) by A13,A8,XREAL_1:8;
A17:  s2+(1-r) > s2 by A14,XREAL_1:29;
A18:  1 <= i+1 by A1,NAT_1:13;
A19:  r1+r2 < r2+r2 by A11,XREAL_1:6;
      then
A20:  s3*(r1+r2) <= s3*(r2+r2) by A5,XREAL_1:64;
A21:  Int cell(G,i,width G) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,
      1)`1 & G* (1,width G)`2 < s9 } by A1,A2,Th25;
A22:  r3*(r2+r2)+s3*(r2+r2) = r2;
      r3*(r1+r2) < r3*(r2+r2) by A15,A19,XREAL_1:68;
      then
A23:  r3*(r1+r2)+s3*(r1+r2) < r2 by A20,A22,XREAL_1:8;
A24:  G*(i,width G) = |[G*(i,width G)`1,G*(i,width G)`2]| by EUCLID:53
        .= |[G*(i,width G)`1,s2]| by A1,A2,A10,GOBOARD5:1
        .= |[r1,s2]| by A1,A2,A10,GOBOARD5:2;
A25:  G*(i+1,width G) = |[G*(i+1,width G)`1,G*(i+1,width G)`2]| by EUCLID:53
        .= |[G*(i+1,width G)`1,s2]| by A18,A9,A10,GOBOARD5:1
        .= |[r2,s2]| by A18,A9,A10,GOBOARD5:2;
      p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G)))+(1-r)*|[0,1]| +r*(1
      /2*(G*(i,width G)+G* (i+1,width G))) by A4,RLVECT_1:def 5
        .= r3*(G*(i,width G)+G*(i+1,width G))+(1-r)*|[0,1]|+ r*(1/2*(G*(i,
      width G)+G*(i+1,width G))) by RLVECT_1:def 7
        .= r3*(G*(i,width G)+G*(i+1,width G))+|[(1-r)*0,(1-r)*1]|+ r*(1/2*(G
      *(i,width G)+G*(i+1,width G))) by EUCLID:58
        .= r3*(G*(i,width G)+G*(i+1,width G))+|[0,1-r]|+ s3*(G*(i,width G)+G
      *(i+1,width G)) by RLVECT_1:def 7
        .= r3*|[r1+r2,s2+s2]|+|[0,1-r]|+s3*(G*(i,width G)+G*(i+1,width G))
      by A25,A24,EUCLID:56
        .= r3*|[r1+r2,s2+s2]|+|[0,1-r]|+s3*|[r1+r2,s2+s2]| by A25,A24,EUCLID:56
        .= |[r3*(r1+r2),r3*(s2+s2)]|+|[0,1-r]|+s3*|[r1+r2,s2+s2]| by EUCLID:58
        .= |[r3*(r1+r2),r3*(s2+s2)]|+|[0,1-r]|+|[s3*(r1+r2),s3*(s2+s2)]| by
EUCLID:58
        .= |[r3*(r1+r2)+0,r3*(s2+s2)+(1-r)]|+|[s3*(r1+r2),s3*(s2+s2)]| by
EUCLID:56
        .= |[r3*(r1+r2)+s3*(r1+r2),r3*(s2+s2)+(1-r)+s3*(s2+s2)]| by EUCLID:56;
      hence p in Int cell(G,i,width G) by A17,A16,A23,A21;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th48:
  1 <= j & j < width G implies LSeg(1/2*(G*(1,j)+G*(1,j+1)) - |[1,
  0]|,G*(1,j) - |[1,0]|) c= Int cell(G,0,j) \/ { G*(1,j) - |[1,0]| }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|,G*(1,j) - |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|)+r*(G*(1,j) - |[1,0]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,j) - |[1,0]|) by A4,RLVECT_1:10
        .= 1*(G*(1,j) - |[1,0]|) by RLVECT_1:4
        .= (G*(1,j) - |[1,0]|) by RLVECT_1:def 8;
      hence p in { G*(1,j) - |[1,0]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set r2 = G*(1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A9:   r3*(s1+s1)+r*s1 = s1;
A10:  j+1 <= width G by A2,NAT_1:13;
      r2 < r2+1 by XREAL_1:29;
      then
A11:  r2-1 < r2 by XREAL_1:19;
A12:  Int cell(G,0,j) = { |[r9,s9]| : r9 < G*(1,1)`1 & G*(1,j)`2 < s9 &
      s9 < G*(1,j+1)`2 } by A1,A2,Th20;
      0 <> len G by MATRIX_0:def 10;
      then
A13:  1 <= len G by NAT_1:14;
      j < j+1 by XREAL_1:29;
      then
A14:  s1 < s2 by A1,A10,A13,GOBOARD5:4;
      then s1+s2 < s2+s2 by XREAL_1:6;
      then
A15:  r3*(s1+s2) < r3*(s2+s2) by A8,XREAL_1:68;
      s1+s1 < s1+s2 by A14,XREAL_1:6;
      then r3*(s1+s1) < r3*(s1+s2) by A8,XREAL_1:68;
      then
A16:  s1 < r3*(s1+s2)+r*s1 by A9,XREAL_1:6;
A17:  r3*(s2+s2)+r*s2 = s2;
      r*s1 <= r*s2 by A5,A14,XREAL_1:64;
      then
A18:  r3*(s1+s2)+r*s1 < s2 by A15,A17,XREAL_1:8;
A19:  G*(1,j) = |[G*(1,j)`1,G*(1,j)`2]| by EUCLID:53
        .= |[r2,s1]| by A1,A2,A13,GOBOARD5:2;
A20:  1 <= j+1 by A1,NAT_1:13;
A21:  G*(1,j+1) = |[G*(1,j+1)`1,G*(1,j+1)`2]| by EUCLID:53
        .= |[r2,s2]| by A20,A10,A13,GOBOARD5:2;
      p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1)))-(1-r)*|[1,0]| +r*(G*(1,j) - |[1
      ,0]|) by A4,RLVECT_1:34
        .= r3*(G*(1,j)+G*(1,j+1))-(1-r)*|[1,0]|+r*(G* (1,j) - |[1,0]|) by
RLVECT_1:def 7
        .= r3*(G*(1,j)+G*(1,j+1))-|[(1-r)*1,(1-r)*0]|+r*(G*(1,j) - |[1,0]|)
      by EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+r*(|[r2,s1]| - |[1,0]|) by A21,A19,
EUCLID:56
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(r*|[r2,s1]| - r*|[1,0]|) by
RLVECT_1:34
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(|[r*r2,r*s1]| - r*|[1,0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(|[r*r2,r*s1]| - |[r*1,r*0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+|[r*r2-r,r*s1-0]| by EUCLID:62
        .= |[r3*(r2+r2),r3*(s1+s2)]|-|[1-r,0]|+|[r*r2-r,r*s1-0]| by EUCLID:58
        .= |[r3*(r2+r2)-(1-r),r3*(s1+s2)-0]|+|[r*r2-r,r*s1-0]| by EUCLID:62
        .= |[r3*(r2+r2)-(1-r)+(r*r2-r),r3*(s1+s2)+r*s1]| by EUCLID:56;
      hence p in Int cell(G,0,j) by A11,A16,A18,A12;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th49:
  1 <= j & j < width G implies LSeg(1/2*(G*(1,j)+G*(1,j+1)) - |[1,
  0]|,G*(1,j+1) - |[1,0]|) c= Int cell(G,0,j) \/ { G*(1,j+1) - |[1,0]| }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|,G*(1,j+1) - |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|)+r*(G*(1,j+1) - |[1,0]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,j+1) - |[1,0]|) by A4,RLVECT_1:10
        .= 1*(G*(1,j+1) - |[1,0]|) by RLVECT_1:4
        .= (G*(1,j+1) - |[1,0]|) by RLVECT_1:def 8;
      hence p in { G*(1,j+1) - |[1,0]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set r2 = G*(1,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A9:   r3*(s1+s1)+r*s1 = s1;
A10:  j+1 <= width G by A2,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A11:  1 <= len G by NAT_1:14;
      j < j+1 by XREAL_1:29;
      then
A12:  s1 < s2 by A1,A10,A11,GOBOARD5:4;
      then s1+s1 < s1+s2 by XREAL_1:6;
      then
A13:  r3*(s1+s1) < r3*(s1+s2) by A8,XREAL_1:68;
      r*s1 <= r*s2 by A5,A12,XREAL_1:64;
      then
A14:  s1 < r3*(s1+s2)+r*s2 by A13,A9,XREAL_1:8;
A15:  1 <= j+1 by A1,NAT_1:13;
A16:  G*(1,j) = |[G*(1,j)`1,G*(1,j)`2]| by EUCLID:53
        .= |[r2,s1]| by A1,A2,A11,GOBOARD5:2;
      r2 < r2+1 by XREAL_1:29;
      then
A17:  r2-1 < r2 by XREAL_1:19;
A18:  r3*(s2+s2)+r*s2 = s2;
      s1+s2 < s2+s2 by A12,XREAL_1:6;
      then r3*(s1+s2) < r3*(s2+s2) by A8,XREAL_1:68;
      then
A19:  r3*(s1+s2)+r*s2 < s2 by A18,XREAL_1:8;
A20:  Int cell(G,0,j) = { |[r9,s9]| : r9 < G*(1,1)`1 & G*(1,j)`2 < s9 &
      s9 < G*(1,j+1)`2 } by A1,A2,Th20;
A21:  G*(1,j+1) = |[G*(1,j+1)`1,G*(1,j+1)`2]| by EUCLID:53
        .= |[r2,s2]| by A15,A10,A11,GOBOARD5:2;
      p = (1-r)*(1/2*(G*(1,j)+G*(1,j+1)))-(1-r)*|[1,0]| +r*(G*(1,j+1) -
      |[1,0]|) by A4,RLVECT_1:34
        .= r3*(G*(1,j)+G*(1,j+1))-(1-r)*|[1,0]|+r*(G*(1,j+1) - |[1,0]|) by
RLVECT_1:def 7
        .= r3*(G*(1,j)+G*(1,j+1))-|[(1-r)*1,(1-r)*0]|+r*(G*(1,j+1) - |[1,0]|
      ) by EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+r*(|[r2,s2]| - |[1,0]|) by A21,A16,
EUCLID:56
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(r*|[r2,s2]| - r*|[1,0]|) by
RLVECT_1:34
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(|[r*r2,r*s2]| - r*|[1,0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+(|[r*r2,r*s2]| - |[r*1,r*0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|-|[1-r,0]|+|[r*r2-r,r*s2-0]| by EUCLID:62
        .= |[r3*(r2+r2),r3*(s1+s2)]|-|[1-r,0]|+|[r*r2-r,r*s2-0]| by EUCLID:58
        .= |[r3*(r2+r2)-(1-r),r3*(s1+s2)-0]|+|[r*r2-r,r*s2-0]| by EUCLID:62
        .= |[r3*(r2+r2)-(1-r)+(r*r2-r),r3*(s1+s2)+r*s2]| by EUCLID:56;
      hence p in Int cell(G,0,j) by A17,A14,A19,A20;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th50:
  1 <= j & j < width G implies LSeg(1/2*(G*(len G,j)+G*(len G,j+1)
) + |[1,0]|,G*(len G,j) + |[1,0]|) c= Int cell(G,len G,j) \/ { G*(len G,j) + |[
  1,0]| }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|,G* (len G,j) + |[1 ,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|)+ r*(G*(len G,j)
  + |[1,0]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,j) + |[1,0]|) by A4,RLVECT_1:10
        .= 1*(G*(len G,j) + |[1,0]|) by RLVECT_1:4
        .= (G*(len G,j) + |[1,0]|) by RLVECT_1:def 8;
      hence p in { G*(len G,j) + |[1,0]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set r2 = G*(len G,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A9:   r3*(s1+s1)+r*s1 = s1;
A10:  j+1 <= width G by A2,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A11:  1 <= len G by NAT_1:14;
A12:  G*(len G,j) = |[G*(len G,j)`1,G*(len G,j)`2]| by EUCLID:53
        .= |[r2,G*(len G,j)`2]| by A1,A2,A11,GOBOARD5:2
        .= |[r2,s1]| by A1,A2,A11,GOBOARD5:1;
A13:  1 <= j+1 by A1,NAT_1:13;
      j < j+1 by XREAL_1:29;
      then
A14:  s1 < s2 by A1,A10,A11,GOBOARD5:4;
      then s1+s2 < s2+s2 by XREAL_1:6;
      then
A15:  r3*(s1+s2) < r3*(s2+s2) by A8,XREAL_1:68;
      s1+s1 < s1+s2 by A14,XREAL_1:6;
      then r3*(s1+s1) < r3*(s1+s2) by A8,XREAL_1:68;
      then
A16:  r2 < r2+1 & s1 < r3*(s1+s2)+r*s1 by A9,XREAL_1:6,29;
A17:  Int cell(G,len G,j) = { |[r9,s9]| : G*(len G,1)`1 < r9 & G*(1,j)`2
      < s9 & s9 < G*(1,j+1)`2 } by A1,A2,Th23;
A18:  G*(len G,j+1) = |[G*(len G,j+1)`1,G*(len G,j+1)`2]| by EUCLID:53
        .= |[r2,G*(len G,j+1)`2]| by A13,A10,A11,GOBOARD5:2
        .= |[r2,s2]| by A13,A10,A11,GOBOARD5:1;
A19:  r3*(s2+s2)+r*s2 = s2;
      r*s1 <= r*s2 by A5,A14,XREAL_1:64;
      then
A20:  r3*(s1+s2)+r*s1 < s2 by A15,A19,XREAL_1:8;
      p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1)))+(1-r)*|[1,0]| +r*(G*(
      len G,j) + |[1,0]|) by A4,RLVECT_1:def 5
        .= r3*(G*(len G,j)+G*(len G,j+1))+(1-r)*|[1,0]|+r*(G* (len G,j) + |[
      1,0]|) by RLVECT_1:def 7
        .= r3*(G*(len G,j)+G*(len G,j+1))+|[(1-r)*1,(1-r)*0]|+ r*(G*(len G,j
      ) + |[1,0]|) by EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+r*(|[r2,s1]| + |[1,0]|) by A18,A12,
EUCLID:56
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(r*|[r2,s1]| + r*|[1,0]|) by
RLVECT_1:def 5
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(|[r*r2,r*s1]| + r*|[1,0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(|[r*r2,r*s1]| + |[r*1,r*0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+|[r*r2+r,r*s1+0]| by EUCLID:56
        .= |[r3*(r2+r2),r3*(s1+s2)]|+|[1-r,0]|+|[r*r2+r,r*s1+0]| by EUCLID:58
        .= |[r3*(r2+r2)+(1-r),r3*(s1+s2)+0]|+|[r*r2+r,r*s1+0]| by EUCLID:56
        .= |[r3*(r2+r2)+(1-r)+(r*r2+r),r3*(s1+s2)+r*s1]| by EUCLID:56;
      hence p in Int cell(G,len G,j) by A16,A20,A17;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th51:
  1 <= j & j < width G implies LSeg(1/2*(G*(len G,j)+G*(len G,j+1)
) + |[1,0]|,G*(len G,j+1) + |[1,0]|) c= Int cell(G,len G,j) \/ { G*(len G,j+1)
  + |[1,0]| }
proof
  assume that
A1: 1 <= j and
A2: j < width G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|,G* (len G,j+1) +
  |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|)+ r*(G*(len G,j+1
  ) + |[1,0]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,j+1) + |[1,0]|) by A4,RLVECT_1:10

        .= 1*(G*(len G,j+1) + |[1,0]|) by RLVECT_1:4
        .= (G*(len G,j+1) + |[1,0]|) by RLVECT_1:def 8;
      hence p in { G*(len G,j+1) + |[1,0]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set r2 = G*(len G,1)`1, s1 = G*(1,j)`2, s2 = G*(1,j+1)`2;
A9:   r3*(s1+s1)+r*s1 = s1;
A10:  j+1 <= width G by A2,NAT_1:13;
      0 <> len G by MATRIX_0:def 10;
      then
A11:  1 <= len G by NAT_1:14;
      j < j+1 by XREAL_1:29;
      then
A12:  s1 < s2 by A1,A10,A11,GOBOARD5:4;
      then s1+s1 < s1+s2 by XREAL_1:6;
      then
A13:  r3*(s1+s1) < r3*(s1+s2) by A8,XREAL_1:68;
A14:  r3*(s2+s2)+r*s2 = s2;
      s1+s2 < s2+s2 by A12,XREAL_1:6;
      then r3*(s1+s2) < r3*(s2+s2) by A8,XREAL_1:68;
      then
A15:  r3*(s1+s2)+r*s2 < s2 by A14,XREAL_1:8;
A16:  G*(len G,j) = |[G*(len G,j)`1,G*(len G,j)`2]| by EUCLID:53
        .= |[r2,G*(len G,j)`2]| by A1,A2,A11,GOBOARD5:2
        .= |[r2,s1]| by A1,A2,A11,GOBOARD5:1;
A17:  1 <= j+1 by A1,NAT_1:13;
      r*s1 <= r*s2 by A5,A12,XREAL_1:64;
      then
A18:  r2+1 > r2 & s1 < r3*(s1+s2)+r*s2 by A13,A9,XREAL_1:8,29;
A19:  Int cell(G,len G,j) = { |[r9,s9]| : G*(len G,1)`1 < r9 & G*(1,j)`2
      < s9 & s9 < G*(1,j+1)`2 } by A1,A2,Th23;
A20:  G*(len G,j+1) = |[G*(len G,j+1)`1,G*(len G,j+1)`2]| by EUCLID:53
        .= |[r2,G*(len G,j+1)`2]| by A17,A10,A11,GOBOARD5:2
        .= |[r2,s2]| by A17,A10,A11,GOBOARD5:1;
      p = (1-r)*(1/2*(G*(len G,j)+G*(len G,j+1)))+(1-r)*|[1,0]| +r*(G*(
      len G,j+1) + |[1,0]|) by A4,RLVECT_1:def 5
        .= r3*(G*(len G,j)+G*(len G,j+1))+(1-r)*|[1,0]|+ r*(G*(len G,j+1) +
      |[1,0]|) by RLVECT_1:def 7
        .= r3*(G*(len G,j)+G*(len G,j+1))+|[(1-r)*1,(1-r)*0]|+ r*(G*(len G,j
      +1) + |[1,0]|) by EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+r*(|[r2,s2]| + |[1,0]|) by A20,A16,
EUCLID:56
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(r*|[r2,s2]| + r*|[1,0]|) by
RLVECT_1:def 5
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(|[r*r2,r*s2]| + r*|[1,0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+(|[r*r2,r*s2]| + |[r*1,r*0]|) by
EUCLID:58
        .= r3*|[r2+r2,s1+s2]|+|[1-r,0]|+|[r*r2+r,r*s2+0]| by EUCLID:56
        .= |[r3*(r2+r2),r3*(s1+s2)]|+|[1-r,0]|+|[r*r2+r,r*s2+0]| by EUCLID:58
        .= |[r3*(r2+r2)+(1-r),r3*(s1+s2)+0]|+|[r*r2+r,r*s2+0]| by EUCLID:56
        .= |[r3*(r2+r2)+(1-r)+(r*r2+r),r3*(s1+s2)+r*s2]| by EUCLID:56;
      hence p in Int cell(G,len G,j) by A18,A15,A19;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th52:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,1)+G*(i+1,1)) - |[0,1
  ]|,G*(i,1) - |[0,1]|) c= Int cell(G,i,0) \/ { G*(i,1) - |[0,1]| }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|,G*(i,1) - |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|)+r*(G*(i,1) - |[0,1]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(i,1) - |[0,1]|) by A4,RLVECT_1:10
        .= 1*(G*(i,1) - |[0,1]|) by RLVECT_1:4
        .= (G*(i,1) - |[0,1]|) by RLVECT_1:def 8;
      hence p in { G*(i,1) - |[0,1]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set s1 = G*(1,1)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A9:   r3*(r1+r1)+r*r1 = r1;
A10:  i+1 <= len G by A2,NAT_1:13;
      s1 < s1+1 by XREAL_1:29;
      then
A11:  s1-1 < s1 by XREAL_1:19;
A12:  Int cell(G,i,0) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,1)`1 &
      s9 < G*(1,1)`2 } by A1,A2,Th24;
      0 <> width G by MATRIX_0:def 10;
      then
A13:  1 <= width G by NAT_1:14;
      i < i+1 by XREAL_1:29;
      then
A14:  r1 < r2 by A1,A10,A13,GOBOARD5:3;
      then r1+r2 < r2+r2 by XREAL_1:6;
      then
A15:  r3*(r1+r2) < r3*(r2+r2) by A8,XREAL_1:68;
      r1+r1 < r1+r2 by A14,XREAL_1:6;
      then r3*(r1+r1) < r3*(r1+r2) by A8,XREAL_1:68;
      then
A16:  r1 < r3*(r1+r2)+r*r1 by A9,XREAL_1:6;
A17:  r3*(r2+r2)+r*r2 = r2;
      r*r1 <= r*r2 by A5,A14,XREAL_1:64;
      then
A18:  r3*(r1+r2)+r*r1 < r2 by A15,A17,XREAL_1:8;
A19:  G*(i,1) = |[G*(i,1)`1,G*(i,1)`2]| by EUCLID:53
        .= |[r1,s1]| by A1,A2,A13,GOBOARD5:1;
A20:  1 <= i+1 by A1,NAT_1:13;
A21:  G*(i+1,1) = |[G*(i+1,1)`1,G*(i+1,1)`2]| by EUCLID:53
        .= |[r2,s1]| by A20,A10,A13,GOBOARD5:1;
      p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1)))-(1-r)*|[0,1]| +r*(G*(i,1) - |[0
      ,1]|) by A4,RLVECT_1:34
        .= r3*(G*(i,1)+G*(i+1,1))-(1-r)*|[0,1]|+r*(G* (i,1) - |[0,1]|) by
RLVECT_1:def 7
        .= r3*(G*(i,1)+G*(i+1,1))-|[(1-r)*0,(1-r)*1]|+r*(G*(i,1) - |[0,1]|)
      by EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+r*(|[r1,s1]| - |[0,1]|) by A21,A19,
EUCLID:56
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(r*|[r1,s1]| - r*|[0,1]|) by
RLVECT_1:34
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(|[r*r1,r*s1]| - r*|[0,1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(|[r*r1,r*s1]| - |[r*0,r*1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+|[r*r1-0,r*s1-r]| by EUCLID:62
        .= |[r3*(r1+r2),r3*(s1+s1)]|-|[0,1-r]|+|[r*r1-0,r*s1-r]| by EUCLID:58
        .= |[r3*(r1+r2)-0,r3*(s1+s1)-(1-r)]|+|[r*r1-0,r*s1-r]| by EUCLID:62
        .= |[r3*(r1+r2)+r*r1,r3*(s1+s1)-(1-r)+(r*s1-r)]| by EUCLID:56;
      hence p in Int cell(G,i,0) by A11,A16,A18,A12;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th53:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,1)+G*(i+1,1)) - |[0,1
  ]|,G*(i+1,1) - |[0,1]|) c= Int cell(G,i,0) \/ { G*(i+1,1) - |[0,1]| }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|,G*(i+1,1) - |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|)+r*(G*(i+1,1) - |[0,1]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(i+1,1) - |[0,1]|) by A4,RLVECT_1:10
        .= 1*(G*(i+1,1) - |[0,1]|) by RLVECT_1:4
        .= (G*(i+1,1) - |[0,1]|) by RLVECT_1:def 8;
      hence p in { G*(i+1,1) - |[0,1]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set s1 = G*(1,1)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A9:   r3*(r1+r1)+r*r1 = r1;
A10:  i+1 <= len G by A2,NAT_1:13;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
      i < i+1 by XREAL_1:29;
      then
A12:  r1 < r2 by A1,A10,A11,GOBOARD5:3;
      then r1+r1 < r1+r2 by XREAL_1:6;
      then
A13:  r3*(r1+r1) < r3*(r1+r2) by A8,XREAL_1:68;
      r*r1 <= r*r2 by A5,A12,XREAL_1:64;
      then
A14:  r1 < r3*(r1+r2)+r*r2 by A13,A9,XREAL_1:8;
A15:  1 <= i+1 by A1,NAT_1:13;
A16:  G*(i,1) = |[G*(i,1)`1,G*(i,1)`2]| by EUCLID:53
        .= |[r1,s1]| by A1,A2,A11,GOBOARD5:1;
      s1 < s1+1 by XREAL_1:29;
      then
A17:  s1-1 < s1 by XREAL_1:19;
A18:  r3*(r2+r2)+r*r2 = r2;
      r1+r2 < r2+r2 by A12,XREAL_1:6;
      then r3*(r1+r2) < r3*(r2+r2) by A8,XREAL_1:68;
      then
A19:  r3*(r1+r2)+r*r2 < r2 by A18,XREAL_1:8;
A20:  Int cell(G,i,0) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,1)`1 &
      s9 < G*(1,1)`2 } by A1,A2,Th24;
A21:  G*(i+1,1) = |[G*(i+1,1)`1,G*(i+1,1)`2]| by EUCLID:53
        .= |[r2,s1]| by A15,A10,A11,GOBOARD5:1;
      p = (1-r)*(1/2*(G*(i,1)+G*(i+1,1)))-(1-r)*|[0,1]| +r*(G*(i+1,1) -
      |[0,1]|) by A4,RLVECT_1:34
        .= r3*(G*(i,1)+G*(i+1,1))-(1-r)*|[0,1]|+r*(G*(i+1,1) - |[0,1]|) by
RLVECT_1:def 7
        .= r3*(G*(i,1)+G*(i+1,1))-|[(1-r)*0,(1-r)*1]|+r*(G*(i+1,1) - |[0,1]|
      ) by EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+r*(|[r2,s1]| - |[0,1]|) by A21,A16,
EUCLID:56
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(r*|[r2,s1]| - r*|[0,1]|) by
RLVECT_1:34
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(|[r*r2,r*s1]| - r*|[0,1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+(|[r*r2,r*s1]| - |[r*0,r*1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|-|[0,1-r]|+|[r*r2-0,r*s1-r]| by EUCLID:62
        .= |[r3*(r1+r2),r3*(s1+s1)]|-|[0,1-r]|+|[r*r2-0,r*s1-r]| by EUCLID:58
        .= |[r3*(r1+r2)-0,r3*(s1+s1)-(1-r)]|+|[r*r2-0,r*s1-r]| by EUCLID:62
        .= |[r3*(r1+r2)+r*r2,r3*(s1+s1)-(1-r)+(r*s1-r)]| by EUCLID:56;
      hence p in Int cell(G,i,0) by A17,A14,A19,A20;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th54:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,width G)+G*(i+1,width
  G)) + |[0,1]|,G* (i,width G) + |[0,1]|) c= Int cell(G,i,width G) \/ { G*(i,
  width G) + |[0,1]| }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|, G*(i,width G)
  + |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|)+ r*(G*(i,
  width G) + |[0,1]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(i,width G) + |[0,1]|) by A4,RLVECT_1:10

        .= 1*(G*(i,width G) + |[0,1]|) by RLVECT_1:4
        .= (G*(i,width G) + |[0,1]|) by RLVECT_1:def 8;
      hence p in { G*(i,width G) + |[0,1]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set s1 = G*(1,width G)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A9:   r3*(r1+r1)+r*r1 = r1;
A10:  i+1 <= len G by A2,NAT_1:13;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
A12:  G*(i,width G) = |[G*(i,width G)`1,G*(i,width G)`2]| by EUCLID:53
        .= |[G*(i,width G)`1,s1]| by A1,A2,A11,GOBOARD5:1
        .= |[r1,s1]| by A1,A2,A11,GOBOARD5:2;
A13:  1 <= i+1 by A1,NAT_1:13;
      i < i+1 by XREAL_1:29;
      then
A14:  r1 < r2 by A1,A10,A11,GOBOARD5:3;
      then r1+r2 < r2+r2 by XREAL_1:6;
      then
A15:  r3*(r1+r2) < r3*(r2+r2) by A8,XREAL_1:68;
      r1+r1 < r1+r2 by A14,XREAL_1:6;
      then r3*(r1+r1) < r3*(r1+r2) by A8,XREAL_1:68;
      then
A16:  s1 < s1+1 & r1 < r3*(r1+r2)+r*r1 by A9,XREAL_1:6,29;
A17:  Int cell(G,i,width G) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,
      1)`1 & G*(1,width G)`2 < s9 } by A1,A2,Th25;
A18:  G*(i+1,width G) = |[G*(i+1,width G)`1,G*(i+1,width G)`2]| by EUCLID:53
        .= |[G*(i+1,width G)`1,s1]| by A13,A10,A11,GOBOARD5:1
        .= |[r2,s1]| by A13,A10,A11,GOBOARD5:2;
A19:  r3*(r2+r2)+r*r2 = r2;
      r*r1 <= r*r2 by A5,A14,XREAL_1:64;
      then
A20:  r3*(r1+r2)+r*r1 < r2 by A15,A19,XREAL_1:8;
      p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G)))+(1-r)*|[0,1]| +r*(G
      *(i,width G) + |[0,1]|) by A4,RLVECT_1:def 5
        .= r3*(G*(i,width G)+G*(i+1,width G))+(1-r)*|[0,1]|+ r*(G*(i,width G
      ) + |[0,1]|) by RLVECT_1:def 7
        .= r3*(G*(i,width G)+G*(i+1,width G))+|[(1-r)*0,(1-r)*1]|+ r*(G*(i,
      width G) + |[0,1]|) by EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+r*(|[r1,s1]| + |[0,1]|) by A18,A12,
EUCLID:56
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(r*|[r1,s1]| + r*|[0,1]|) by
RLVECT_1:def 5
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(|[r*r1,r*s1]| + r*|[0,1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(|[r*r1,r*s1]| + |[r*0,r*1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+|[r*r1+0,r*s1+r]| by EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s1)]|+|[0,1-r]|+|[r*r1+0,r*s1+r]| by EUCLID:58
        .= |[r3*(r1+r2)+0,r3*(s1+s1)+(1-r)]|+|[r*r1+0,r*s1+r]| by EUCLID:56
        .= |[r3*(r1+r2)+r*r1,r3*(s1+s1)+(1-r)+(r*s1+r)]| by EUCLID:56;
      hence p in Int cell(G,i,width G) by A16,A20,A17;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th55:
  1 <= i & i < len G implies LSeg(1/2*(G*(i,width G)+G*(i+1,width
G)) + |[0,1]|,G* (i+1,width G) + |[0,1]|) c= Int cell(G,i,width G) \/ { G*(i+1,
  width G) + |[0,1]| }
proof
  assume that
A1: 1 <= i and
A2: i < len G;
  let x be object;
  assume
A3: x in LSeg(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|, G*(i+1,width
  G) + |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A4: p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|)+ r*(G*(i+1,
  width G) + |[0,1]|) and
A5: 0<=r and
A6: r<=1 by A3;
  now
    per cases by A6,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(i+1,width G) + |[0,1]|) by A4,RLVECT_1:10

        .= 1*(G*(i+1,width G) + |[0,1]|) by RLVECT_1:4
        .= (G*(i+1,width G) + |[0,1]|) by RLVECT_1:def 8;
      hence p in { G*(i+1,width G) + |[0,1]| } by TARSKI:def 1;
    end;
    case
A7:   r < 1;
      set r3 = (1-r)*(1/2);
      1 - r > 0 by A7,XREAL_1:50;
      then
A8:   r3 > (1/2)*0 by XREAL_1:68;
      set s1 = G*(1,width G)`2, r1 = G*(i,1)`1, r2 = G*(i+1,1)`1;
A9:   r3*(r1+r1)+r*r1 = r1;
A10:  i+1 <= len G by A2,NAT_1:13;
      0 <> width G by MATRIX_0:def 10;
      then
A11:  1 <= width G by NAT_1:14;
      i < i+1 by XREAL_1:29;
      then
A12:  r1 < r2 by A1,A10,A11,GOBOARD5:3;
      then r1+r1 < r1+r2 by XREAL_1:6;
      then
A13:  r3*(r1+r1) < r3*(r1+r2) by A8,XREAL_1:68;
A14:  r3*(r2+r2)+r*r2 = r2;
      r1+r2 < r2+r2 by A12,XREAL_1:6;
      then r3*(r1+r2) < r3*(r2+r2) by A8,XREAL_1:68;
      then
A15:  r3*(r1+r2)+r*r2 < r2 by A14,XREAL_1:8;
A16:  G*(i,width G) = |[G*(i,width G)`1,G*(i,width G)`2]| by EUCLID:53
        .= |[G*(i,width G)`1,s1]| by A1,A2,A11,GOBOARD5:1
        .= |[r1,s1]| by A1,A2,A11,GOBOARD5:2;
A17:  1 <= i+1 by A1,NAT_1:13;
      r*r1 <= r*r2 by A5,A12,XREAL_1:64;
      then
A18:  s1+1 > s1 & r1 < r3*(r1+r2)+r*r2 by A13,A9,XREAL_1:8,29;
A19:  Int cell(G,i,width G) = { |[r9,s9]| : G*(i,1)`1 < r9 & r9 < G*(i+1,
      1)`1 & G*(1,width G)`2 < s9 } by A1,A2,Th25;
A20:  G*(i+1,width G) = |[G*(i+1,width G)`1,G*(i+1,width G)`2]| by EUCLID:53
        .= |[G*(i+1,width G)`1,s1]| by A17,A10,A11,GOBOARD5:1
        .= |[r2,s1]| by A17,A10,A11,GOBOARD5:2;
      p = (1-r)*(1/2*(G*(i,width G)+G*(i+1,width G)))+(1-r)*|[0,1]| +r*(G
      *(i+1,width G) + |[0,1]|) by A4,RLVECT_1:def 5
        .= r3*(G*(i,width G)+G*(i+1,width G))+(1-r)*|[0,1]|+ r*(G*(i+1,width
      G) + |[0,1]|) by RLVECT_1:def 7
        .= r3*(G*(i,width G)+G*(i+1,width G))+|[(1-r)*0,(1-r)*1]|+ r*(G*(i+1
      ,width G) + |[0,1]|) by EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+r*(|[r2,s1]| + |[0,1]|) by A20,A16,
EUCLID:56
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(r*|[r2,s1]| + r*|[0,1]|) by
RLVECT_1:def 5
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(|[r*r2,r*s1]| + r*|[0,1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+(|[r*r2,r*s1]| + |[r*0,r*1]|) by
EUCLID:58
        .= r3*|[r1+r2,s1+s1]|+|[0,1-r]|+|[r*r2+0,r*s1+r]| by EUCLID:56
        .= |[r3*(r1+r2),r3*(s1+s1)]|+|[0,1-r]|+|[r*r2+0,r*s1+r]| by EUCLID:58
        .= |[r3*(r1+r2)+0,r3*(s1+s1)+(1-r)]|+|[r*r2+0,r*s1+r]| by EUCLID:56
        .= |[r3*(r1+r2)+r*r2,r3*(s1+s1)+(1-r)+(r*s1+r)]| by EUCLID:56;
      hence p in Int cell(G,i,width G) by A18,A15,A19;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th56:
  LSeg(G*(1,1) - |[1,1]|,G*(1,1) - |[1,0]|) c= Int cell(G,0,0) \/
  { G*(1,1) - |[1,0]| }
proof
  let x be object;
  set r1 = G*(1,1)`1, s1 = G*(1,1)`2;
  assume
A1: x in LSeg(G*(1,1)-|[1,1]|,G*(1,1) - |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(1,1)-|[1,1]|)+r*(G*(1,1) - |[1,0]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,1) - |[1,0]|) by A2,RLVECT_1:10
        .= 1*(G*(1,1) - |[1,0]|) by RLVECT_1:4
        .= G*(1,1) - |[1,0]| by RLVECT_1:def 8;
      hence p in { G*(1,1) - |[1,0]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then s1 < s1 +(1-r) by XREAL_1:29;
      then
A4:   s1-(1-r) < s1 by XREAL_1:19;
A5:   G*(1,1) = |[r1,s1]| by EUCLID:53;
      r1 < r1+1 by XREAL_1:29;
      then
A6:   r1-1 < r1 by XREAL_1:19;
A7:   Int cell(G,0,0) = { |[r9,s9]| : r9 < G*(1,1)`1 & s9 < G* (1,1)`2 }
      by Th18;
      p = (1-r)*(G*(1,1))-(1-r)*|[1,1]|+r*(G*(1,1) - |[1,0]|) by A2,RLVECT_1:34
        .= (1-r)*(G*(1,1))-(1-r)*|[1,1]|+(r*(G*(1,1)) - r*|[1,0]|) by
RLVECT_1:34
        .= r*(G*(1,1)) + ((1-r)*(G*(1,1))-(1-r)*|[1,1]|) - r*|[1,0]| by
RLVECT_1:def 3
        .= r*(G*(1,1)) + (1-r)*(G*(1,1))-(1-r)*|[1,1]| - r*|[1,0]| by
RLVECT_1:def 3
        .= (r+(1-r))*(G*(1,1)) -(1-r)*|[1,1]| - r*|[1,0]| by RLVECT_1:def 6
        .= G*(1,1) -(1-r)*|[1,1]| - r*|[1,0]| by RLVECT_1:def 8
        .= G*(1,1)-|[(1-r)*1,(1-r)*1]| - r*|[1,0]| by EUCLID:58
        .= G*(1,1)-|[1-r,1-r]| - |[r*1,r*0]| by EUCLID:58
        .= |[r1-(1-r),s1-(1-r)]| - |[r,0]| by A5,EUCLID:62
        .= |[r1-(1-r)-r,s1-(1-r)-0]| by EUCLID:62
        .= |[r1-1,s1-(1-r)]|;
      hence p in Int cell(G,0,0) by A4,A6,A7;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th57:
  LSeg(G*(len G,1) + |[1,-1]|,G*(len G,1) + |[1,0]|) c= Int cell(G
  ,len G,0) \/ { G*(len G,1) + |[1,0]| }
proof
  let x be object;
  set r1 = G*(len G,1)`1, s1 = G*(1,1)`2;
  assume
A1: x in LSeg(G*(len G,1)+|[1,-1]|,G*(len G,1) + |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(len G,1)+|[1,-1]|)+r*(G*(len G,1) + |[1,0]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,1) + |[1,0]|) by A2,RLVECT_1:10
        .= 1*(G*(len G,1) + |[1,0]|) by RLVECT_1:4
        .= G*(len G,1) + |[1,0]| by RLVECT_1:def 8;
      hence p in { G*(len G,1) + |[1,0]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then
A4:   s1 < s1 +(1-r) by XREAL_1:29;
      s1+(r-1) = s1-(1-r);
      then
A5:   s1+(r-1) < s1 by A4,XREAL_1:19;
A6:   r1 < r1+1 by XREAL_1:29;
      0 <> len G by MATRIX_0:def 10;
      then
A7:   1 <= len G by NAT_1:14;
      0 <> width G by MATRIX_0:def 10;
      then
A8:   1 <= width G by NAT_1:14;
A9:   G*(len G,1) = |[r1,G*(len G,1)`2]| by EUCLID:53
        .= |[r1,s1]| by A8,A7,GOBOARD5:1;
A10:  Int cell(G,len G,0) = { |[r9,s9]| : G*(len G,1)`1 < r9 & s9 < G*(1,
      1)`2 } by Th21;
      p = (1-r)*(G*(len G,1))+(1-r)*|[1,-1]|+r*(G*(len G,1) + |[1,0]|) by A2,
RLVECT_1:def 5
        .= (1-r)*(G*(len G,1))+(1-r)*|[1,-1]|+(r*(G*(len G,1)) + r*|[1,0]|)
      by RLVECT_1:def 5
        .= r*(G*(len G,1)) + ((1-r)*(G*(len G,1))+(1-r)*|[1,-1]|) + r*|[1,0
      ]| by RLVECT_1:def 3
        .= r*(G*(len G,1)) + (1-r)*(G*(len G,1))+(1-r)*|[1,-1]| + r*|[1,0]|
      by RLVECT_1:def 3
        .= (r+(1-r))*(G*(len G,1)) +(1-r)*|[1,-1]| + r*|[1,0]| by
RLVECT_1:def 6
        .= G*(len G,1) +(1-r)*|[1,-1]| + r*|[1,0]| by RLVECT_1:def 8
        .= G*(len G,1)+|[(1-r)*1,(1-r)*(-1)]| + r*|[1,0]| by EUCLID:58
        .= G*(len G,1)+|[1-r,r-1]| + |[r*1,r*0]| by EUCLID:58
        .= |[r1+(1-r),s1+(r-1)]| + |[r,0]| by A9,EUCLID:56
        .= |[r1+(1-r)+r,s1+(r-1)+0]| by EUCLID:56
        .= |[r1+1,s1+(r-1)]|;
      hence p in Int cell(G,len G,0) by A5,A6,A10;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th58:
  LSeg(G*(1,width G) + |[-1,1]|,G*(1,width G) - |[1,0]|) c= Int
  cell(G,0,width G) \/ { G*(1,width G) - |[1,0]| }
proof
  let x be object;
  set r1 = G*(1,1)`1, s1 = G*(1,width G)`2;
  assume
A1: x in LSeg(G*(1,width G)+|[-1,1]|,G*(1,width G) - |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(1,width G)+|[-1,1]|)+r*(G*(1,width G) - |[1,0]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,width G) - |[1,0]|) by A2,RLVECT_1:10

        .= 1*(G*(1,width G) - |[1,0]|) by RLVECT_1:4
        .= G*(1,width G) - |[1,0]| by RLVECT_1:def 8;
      hence p in { G*(1,width G) - |[1,0]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then
A4:   s1 < s1 +(1-r) by XREAL_1:29;
      0 <> width G by MATRIX_0:def 10;
      then
A5:   1 <= width G by NAT_1:14;
      0 <> len G by MATRIX_0:def 10;
      then
A6:   1 <= len G by NAT_1:14;
A7:   G*(1,width G) = |[G*(1,width G)`1,s1]| by EUCLID:53
        .= |[r1,s1]| by A5,A6,GOBOARD5:2;
A8:   Int cell(G,0,width G) = { |[r9,s9]| : r9 < G*(1,1)`1 & G*(1,width G
      )`2 < s9 } by Th19;
      r1 < r1+1 by XREAL_1:29;
      then
A9:   r1-1 < r1 by XREAL_1:19;
      p = (1-r)*(G*(1,width G))+(1-r)*|[-1,1]|+r*(G*(1,width G) - |[1,0]|
      ) by A2,RLVECT_1:def 5
        .= (1-r)*(G*(1,width G))+(1-r)*|[-1,1]|+(r*(G*(1,width G)) - r*|[1,0
      ]|) by RLVECT_1:34
        .= r*(G*(1,width G)) + ((1-r)*(G* (1,width G))+(1-r)*|[-1,1]|) - r*
      |[1,0]| by RLVECT_1:def 3
        .= r*(G*(1,width G)) + (1-r)*(G*(1,width G))+(1-r)*|[-1,1]| - r*|[1,
      0]| by RLVECT_1:def 3
        .= (r+(1-r))*(G*(1,width G)) +(1-r)*|[-1,1]| - r*|[1,0]| by
RLVECT_1:def 6
        .= G*(1,width G) +(1-r)*|[-1,1]| - r*|[1,0]| by RLVECT_1:def 8
        .= G*(1,width G)+|[(1-r)*(-1),(1-r)*1]| - r*|[1,0]| by EUCLID:58
        .= G*(1,width G)+|[r-1,1-r]| - |[r*1,r*0]| by EUCLID:58
        .= |[r1+(r-1),s1+(1-r)]| - |[r,0]| by A7,EUCLID:56
        .= |[r1+(r-1)-r,s1+(1-r)-0]| by EUCLID:62
        .= |[r1-1,s1+(1-r)]|;
      hence p in Int cell(G,0,width G) by A4,A9,A8;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th59:
  LSeg(G*(len G,width G) + |[1,1]|,G*(len G,width G) + |[1,0]|) c=
  Int cell(G,len G,width G) \/ { G*(len G,width G) + |[1,0]| }
proof
  let x be object;
  set r1 = G*(len G,1)`1, s1 = G*(1,width G)`2;
  assume
A1: x in LSeg(G*(len G,width G)+|[1,1]|,G*(len G,width G) + |[1,0]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(len G,width G)+|[1,1]|)+r*(G*(len G,width G) + |[1,0]| ) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,width G) + |[1,0]|) by A2,RLVECT_1:10

        .= 1*(G*(len G,width G) + |[1,0]|) by RLVECT_1:4
        .= G*(len G,width G) + |[1,0]| by RLVECT_1:def 8;
      hence p in { G*(len G,width G) + |[1,0]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then
A4:   s1 < s1 +(1-r) by XREAL_1:29;
A5:   r1 < r1+1 by XREAL_1:29;
      0 <> width G by MATRIX_0:def 10;
      then
A6:   1 <= width G by NAT_1:14;
      0 <> len G by MATRIX_0:def 10;
      then
A7:   1 <= len G by NAT_1:14;
A8:   G*(len G,width G) = |[G*(len G,width G)`1,G*(len G,width G)`2]| by
EUCLID:53
        .= |[r1,G*(len G,width G)`2]| by A6,A7,GOBOARD5:2
        .= |[r1,s1]| by A6,A7,GOBOARD5:1;
A9:   Int cell(G,len G,width G) = { |[r9,s9]| : G*(len G,1)`1 < r9 & G*(1
      ,width G)`2 < s9 } by Th22;
      p = (1-r)*(G*(len G,width G))+(1-r)*|[1,1]|+r*(G* (len G,width G) +
      |[1,0]|) by A2,RLVECT_1:def 5
        .= (1-r)*(G*(len G,width G))+(1-r)*|[1,1]|+(r*(G* (len G,width G)) +
      r*|[1,0]|) by RLVECT_1:def 5
        .= r*(G*(len G,width G))+((1-r)*(G* (len G,width G))+(1-r)*|[1,1]|)
      + r*|[1,0]| by RLVECT_1:def 3
        .= r*(G*(len G,width G)) + (1-r)*(G* (len G,width G))+(1-r)*|[1,1]|
      + r*|[1,0]| by RLVECT_1:def 3
        .= (r+(1-r))*(G*(len G,width G)) +(1-r)*|[1,1]| + r*|[1,0]| by
RLVECT_1:def 6
        .= G*(len G,width G) +(1-r)*|[1,1]| + r*|[1,0]| by RLVECT_1:def 8
        .= G*(len G,width G)+|[(1-r)*1,(1-r)*1]| + r*|[1,0]| by EUCLID:58
        .= G*(len G,width G)+|[1-r,1-r]| + |[r*1,r*0]| by EUCLID:58
        .= |[r1+(1-r),s1+(1-r)]| + |[r,0]| by A8,EUCLID:56
        .= |[r1+(1-r)+r,s1+(1-r)+0]| by EUCLID:56
        .= |[r1+1,s1+(1-r)]|;
      hence p in Int cell(G,len G,width G) by A4,A5,A9;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th60:
  LSeg(G*(1,1) - |[1,1]|,G*(1,1) - |[0,1]|) c= Int cell(G,0,0) \/
  { G*(1,1) - |[0,1]| }
proof
  let x be object;
  set r1 = G*(1,1)`1, s1 = G*(1,1)`2;
  assume
A1: x in LSeg(G*(1,1)-|[1,1]|,G*(1,1) - |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(1,1)-|[1,1]|)+r*(G*(1,1) - |[0,1]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,1) - |[0,1]|) by A2,RLVECT_1:10
        .= 1*(G*(1,1) - |[0,1]|) by RLVECT_1:4
        .= G*(1,1) - |[0,1]| by RLVECT_1:def 8;
      hence p in { G*(1,1) - |[0,1]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then r1 < r1+(1-r) by XREAL_1:29;
      then
A4:   r1-(1-r) < r1 by XREAL_1:19;
A5:   G*(1,1) = |[r1,s1]| by EUCLID:53;
      s1 < s1 +1 by XREAL_1:29;
      then
A6:   s1-1 < s1 by XREAL_1:19;
A7:   Int cell(G,0,0) = { |[r9,s9]| : r9 < G*(1,1)`1 & s9 < G* (1,1)`2 }
      by Th18;
      p = (1-r)*(G*(1,1))-(1-r)*|[1,1]|+r*(G*(1,1) - |[0,1]|) by A2,RLVECT_1:34
        .= (1-r)*(G*(1,1))-(1-r)*|[1,1]|+(r*(G*(1,1)) - r*|[0,1]|) by
RLVECT_1:34
        .= r*(G*(1,1)) + ((1-r)*(G*(1,1))-(1-r)*|[1,1]|) - r*|[0,1]| by
RLVECT_1:def 3
        .= r*(G*(1,1)) + (1-r)*(G*(1,1))-(1-r)*|[1,1]| - r*|[0,1]| by
RLVECT_1:def 3
        .= (r+(1-r))*(G*(1,1)) -(1-r)*|[1,1]| - r*|[0,1]| by RLVECT_1:def 6
        .= G*(1,1) -(1-r)*|[1,1]| - r*|[0,1]| by RLVECT_1:def 8
        .= G*(1,1)-|[(1-r)*1,(1-r)*1]| - r*|[0,1]| by EUCLID:58
        .= G*(1,1)-|[1-r,1-r]| - |[r*0,r*1]| by EUCLID:58
        .= |[r1-(1-r),s1-(1-r)]| - |[0,r]| by A5,EUCLID:62
        .= |[r1-(1-r)-0,s1-(1-r)-r]| by EUCLID:62
        .= |[r1-(1-r),s1-1]|;
      hence p in Int cell(G,0,0) by A6,A4,A7;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th61:
  LSeg(G*(len G,1) + |[1,-1]|,G*(len G,1) - |[0,1]|) c= Int cell(G
  ,len G,0) \/ { G*(len G,1) - |[0,1]| }
proof
  let x be object;
  set r1 = G*(len G,1)`1, s1 = G*(1,1)`2;
  assume
A1: x in LSeg(G*(len G,1)+|[1,-1]|,G*(len G,1) - |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(len G,1)+|[1,-1]|)+r*(G*(len G,1) - |[0,1]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,1) - |[0,1]|) by A2,RLVECT_1:10
        .= 1*(G*(len G,1) - |[0,1]|) by RLVECT_1:4
        .= G*(len G,1) - |[0,1]| by RLVECT_1:def 8;
      hence p in { G*(len G,1) - |[0,1]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then
A4:   r1 < r1+(1-r) by XREAL_1:29;
      s1 < s1+1 by XREAL_1:29;
      then
A5:   s1-1 < s1 by XREAL_1:19;
      0 <> len G by MATRIX_0:def 10;
      then
A6:   1 <= len G by NAT_1:14;
      0 <> width G by MATRIX_0:def 10;
      then
A7:   1 <= width G by NAT_1:14;
A8:   G*(len G,1) = |[r1,G*(len G,1)`2]| by EUCLID:53
        .= |[r1,s1]| by A7,A6,GOBOARD5:1;
A9:   Int cell(G,len G,0) = { |[r9,s9]| : G*(len G,1)`1 < r9 & s9 < G*(1,
      1)`2 } by Th21;
      p = (1-r)*(G*(len G,1))+(1-r)*|[1,-1]|+r*(G*(len G,1) - |[0,1]|) by A2,
RLVECT_1:def 5
        .= (1-r)*(G*(len G,1))+(1-r)*|[1,-1]|+(r*(G*(len G,1)) - r*|[0,1]|)
      by RLVECT_1:34
        .= r*(G*(len G,1)) + ((1-r)*(G*(len G,1))+(1-r)*|[1,-1]|) - r*|[0,1
      ]| by RLVECT_1:def 3
        .= r*(G*(len G,1)) + (1-r)*(G*(len G,1))+(1-r)*|[1,-1]| - r*|[0,1]|
      by RLVECT_1:def 3
        .= (r+(1-r))*(G*(len G,1)) +(1-r)*|[1,-1]| - r*|[0,1]| by
RLVECT_1:def 6
        .= G*(len G,1) +(1-r)*|[1,-1]| - r*|[0,1]| by RLVECT_1:def 8
        .= G*(len G,1)+|[(1-r)*1,(1-r)*(-1)]| - r*|[0,1]| by EUCLID:58
        .= G*(len G,1)+|[1-r,r-1]| - |[r*0,r*1]| by EUCLID:58
        .= |[r1+(1-r),s1+(r-1)]| - |[0,r]| by A8,EUCLID:56
        .= |[r1+(1-r)-0,s1+(r-1)-r]| by EUCLID:62
        .= |[r1+(1-r),s1-1]|;
      hence p in Int cell(G,len G,0) by A5,A4,A9;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th62:
  LSeg(G*(1,width G) + |[-1,1]|,G*(1,width G) + |[0,1]|) c= Int
  cell(G,0,width G) \/ { G*(1,width G) + |[0,1]| }
proof
  let x be object;
  set r1 = G*(1,1)`1, s1 = G*(1,width G)`2;
  assume
A1: x in LSeg(G*(1,width G)+|[-1,1]|,G*(1,width G) + |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(1,width G)+|[-1,1]|)+r*(G*(1,width G) + |[0,1]|) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(1,width G) + |[0,1]|) by A2,RLVECT_1:10

        .= 1*(G*(1,width G) + |[0,1]|) by RLVECT_1:4
        .= G*(1,width G) + |[0,1]| by RLVECT_1:def 8;
      hence p in { G*(1,width G) + |[0,1]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then r1 < r1+(1-r) by XREAL_1:29;
      then
A4:   s1 < s1 +1 & r1-(1-r) < r1 by XREAL_1:19,29;
      0 <> width G by MATRIX_0:def 10;
      then
A5:   1 <= width G by NAT_1:14;
      0 <> len G by MATRIX_0:def 10;
      then
A6:   1 <= len G by NAT_1:14;
A7:   G*(1,width G) = |[G*(1,width G)`1,s1]| by EUCLID:53
        .= |[r1,s1]| by A5,A6,GOBOARD5:2;
A8:   Int cell(G,0,width G) = { |[r9,s9]| : r9 < G*(1,1)`1 & G*(1,width G
      )`2 < s9 } by Th19;
      p = (1-r)*(G*(1,width G))+(1-r)*|[-1,1]|+r*(G*(1,width G) + |[0,1]|
      ) by A2,RLVECT_1:def 5
        .= (1-r)*(G*(1,width G))+(1-r)*|[-1,1]|+(r*(G*(1,width G)) + r*|[0,1
      ]|) by RLVECT_1:def 5
        .= r*(G*(1,width G)) + ((1-r)*(G* (1,width G))+(1-r)*|[-1,1]|) + r*
      |[0,1]| by RLVECT_1:def 3
        .= r*(G*(1,width G)) + (1-r)*(G*(1,width G))+(1-r)*|[-1,1]| + r*|[0,
      1]| by RLVECT_1:def 3
        .= (r+(1-r))*(G*(1,width G)) +(1-r)*|[-1,1]| + r*|[0,1]| by
RLVECT_1:def 6
        .= G*(1,width G) +(1-r)*|[-1,1]| + r*|[0,1]| by RLVECT_1:def 8
        .= G*(1,width G)+|[(1-r)*(-1),(1-r)*1]| + r*|[0,1]| by EUCLID:58
        .= G*(1,width G)+|[r-1,1-r]| + |[r*0,r*1]| by EUCLID:58
        .= |[r1+(r-1),s1+(1-r)]| + |[0,r]| by A7,EUCLID:56
        .= |[r1+(r-1)+0,s1+(1-r)+r]| by EUCLID:56
        .= |[r1-(1-r),s1+1]|;
      hence p in Int cell(G,0,width G) by A4,A8;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th63:
  LSeg(G*(len G,width G) + |[1,1]|,G*(len G,width G) + |[0,1]|) c=
  Int cell(G,len G,width G) \/ { G*(len G,width G) + |[0,1]| }
proof
  let x be object;
  set r1 = G*(len G,1)`1, s1 = G*(1,width G)`2;
  assume
A1: x in LSeg(G*(len G,width G)+|[1,1]|,G*(len G,width G) + |[0,1]|);
  then reconsider p = x as Point of TOP-REAL 2;
  consider r such that
A2: p = (1-r)*(G*(len G,width G)+|[1,1]|)+r*(G*(len G,width G) + |[0,1]| ) and
  0<=r and
A3: r<=1 by A1;
  now
    per cases by A3,XXREAL_0:1;
    case
      r = 1;
      then p = 0.TOP-REAL 2 + 1*(G*(len G,width G) + |[0,1]|) by A2,RLVECT_1:10

        .= 1*(G*(len G,width G) + |[0,1]|) by RLVECT_1:4
        .= G*(len G,width G) + |[0,1]| by RLVECT_1:def 8;
      hence p in { G*(len G,width G) + |[0,1]| } by TARSKI:def 1;
    end;
    case
      r < 1;
      then 1 - r > 0 by XREAL_1:50;
      then
A4:   s1 < s1 +1 & r1 < r1+(1-r) by XREAL_1:29;
      0 <> width G by MATRIX_0:def 10;
      then
A5:   1 <= width G by NAT_1:14;
      0 <> len G by MATRIX_0:def 10;
      then
A6:   1 <= len G by NAT_1:14;
A7:   G*(len G,width G) = |[G*(len G,width G)`1,G*(len G,width G)`2]| by
EUCLID:53
        .= |[r1,G*(len G,width G)`2]| by A5,A6,GOBOARD5:2
        .= |[r1,s1]| by A5,A6,GOBOARD5:1;
A8:   Int cell(G,len G,width G) = { |[r9,s9]| : G*(len G,1)`1 < r9 & G*(1
      ,width G)`2 < s9 } by Th22;
      p = (1-r)*(G*(len G,width G))+(1-r)*|[1,1]|+r*(G* (len G,width G) +
      |[0,1]|) by A2,RLVECT_1:def 5
        .= (1-r)*(G*(len G,width G))+(1-r)*|[1,1]|+(r*(G* (len G,width G)) +
      r*|[0,1]|) by RLVECT_1:def 5
        .= r*(G*(len G,width G))+((1-r)*(G* (len G,width G))+(1-r)*|[1,1]|)
      + r*|[0,1]| by RLVECT_1:def 3
        .= r*(G*(len G,width G)) + (1-r)*(G* (len G,width G))+(1-r)*|[1,1]|
      + r*|[0,1]| by RLVECT_1:def 3
        .= (r+(1-r))*(G*(len G,width G)) +(1-r)*|[1,1]| + r*|[0,1]| by
RLVECT_1:def 6
        .= G*(len G,width G) +(1-r)*|[1,1]| + r*|[0,1]| by RLVECT_1:def 8
        .= G*(len G,width G)+|[(1-r)*1,(1-r)*1]| + r*|[0,1]| by EUCLID:58
        .= G*(len G,width G)+|[1-r,1-r]| + |[r*0,r*1]| by EUCLID:58
        .= |[r1+(1-r),s1+(1-r)]| + |[0,r]| by A7,EUCLID:56
        .= |[r1+(1-r)+0,s1+(1-r)+r]| by EUCLID:56
        .= |[r1+(1-r),s1+1]|;
      hence p in Int cell(G,len G,width G) by A4,A8;
    end;
  end;
  hence thesis by XBOOLE_0:def 3;
end;

theorem
  1 <= i & i < len G & 1 <= j & j+1 < width G implies LSeg(1/2*(G*(i,j)+
G*(i+1,j+1)),1/2*(G*(i,j+1)+G*(i+1,j+2))) c= Int cell(G,i,j) \/ Int cell(G,i,j+
  1) \/ { 1/2*(G*(i,j+1)+G*(i+1,j+1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 <= j and
A4: j+1 < width G;
  set p1 = G*(i,j), p2 = G*(i,j+1), q2 = G*(i+1,j+1), q3 = G*(i+1,j+2), r = (
  p2`2-p1`2)/(q3`2-p1`2);
A5: j+1 >= 1 by NAT_1:11;
  set I1 = Int cell(G,i,j), I2 = Int cell(G,i,j+1);
  j <= j+1 by NAT_1:11;
  then
A6: j < width G by A4,XXREAL_0:2;
  then
A7: LSeg(1/2*(p1+q2),1/2*(p2+q2)) c= I1 \/ { 1/2*(p2+q2) } by A1,A2,A3,Th41;
  j < j+1 by XREAL_1:29;
  then p1`2 < p2`2 by A1,A2,A3,A4,GOBOARD5:4;
  then
A8: p2`2-p1`2 > 0 by XREAL_1:50;
A9: j+1+1 = j+(1+1);
  then
A10: j+2 >= 1 by NAT_1:11;
A11: j+(1+1) <= width G by A4,A9,NAT_1:13;
A12: i+1 >= 1 & i+1 <= len G by A2,NAT_1:11,13;
  then
A13: q2`1 = G*(i+1,1)`1 by A4,A5,GOBOARD5:2
    .= q3`1 by A11,A10,A12,GOBOARD5:2;
A14: q2`2 = G*(1,j+1)`2 by A4,A5,A12,GOBOARD5:1
    .= p2`2 by A1,A2,A4,A5,GOBOARD5:1;
  j+1 < j+2 by XREAL_1:6;
  then q2`2 < q3`2 by A5,A11,A12,GOBOARD5:4;
  then
A15: p2`2-p1`2 < q3`2-p1`2 by A14,XREAL_1:9;
  then
A16: r*(q3`2-p1`2) = p2`2-p1`2 by A8,XCMPLX_1:87;
  p1`1 = G*(i,1)`1 by A1,A2,A3,A6,GOBOARD5:2
    .= p2`1 by A1,A2,A4,A5,GOBOARD5:2;
  then
A17: (p2+q2)`1 = (1-r)*(p1`1+q2`1)+r*(p2`1+q3`1) by A13,Lm1
    .= (1-r)*(p1+q2)`1+r*(p2`1+q3`1) by Lm1
    .= (1-r)*(p1+q2)`1+r*(p2+q3)`1 by Lm1
    .= (1-r)*(p1+q2)`1+(r*(p2+q3))`1 by Lm3
    .= ((1-r)*(p1+q2))`1+(r*(p2+q3))`1 by Lm3
    .= ((1-r)*(p1+q2)+r*(p2+q3))`1 by Lm1;
  (p2+q2)`2 = p2`2+(r+(1-r))*q2`2 by Lm1
    .= (1-r)*(p1`2+q2`2)+r*(p2`2+q3`2) by A14,A16
    .= (1-r)*(p1`2+q2`2)+r*(p2+q3)`2 by Lm1
    .= (1-r)*(p1+q2)`2+r*(p2+q3)`2 by Lm1
    .= (1-r)*(p1+q2)`2+(r*(p2+q3))`2 by Lm3
    .= ((1-r)*(p1+q2))`2+(r*(p2+q3))`2 by Lm3
    .= ((1-r)*(p1+q2)+r*(p2+q3))`2 by Lm1;
  then (1-r)*(p1+q2)+r*(p2+q3) = |[(p2+q2)`1,(p2+q2)`2]| by A17,EUCLID:53
    .= p2+q2 by EUCLID:53;
  then
A18: 1/2*(p2+q2) = (1/2)*((1-r)*(p1+q2))+(1/2)*(r*(p2+q3)) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+q2)+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+q2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+q2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
  r < 1 by A15,A8,XREAL_1:189;
  then 1/2*(p2+q2) in LSeg(1/2*(p1+q2),1/2*(p2+q3)) by A15,A8,A18;
  then
A19: LSeg(1/2*(p1+q2),1/2*(p2+q3)) = LSeg(1/2*(p1+q2),1/2*(p2+q2)) \/ LSeg(1
  /2*(p2+q2),1/2*(p2+q3)) by TOPREAL1:5;
A20: I1 \/ I2 \/ { 1/2*(p2+q2) } = I1 \/ (I2 \/ ({ 1/2*(p2+q2) } \/ { 1/2*(
  p2+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p2+q2) } \/ { 1/2*(p2+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p2+q2) } \/ (I2 \/ { 1/2*(p2+q2) }) by XBOOLE_1:4;
  LSeg(1/2*(p2+q2),1/2*(p2+q3)) c= I2 \/ { 1/2*(p2+q2) } by A1,A2,A4,A5,A9,Th43
;
  hence thesis by A19,A7,A20,XBOOLE_1:13;
end;

theorem
  1 <= j & j < width G & 1 <= i & i+1 < len G implies LSeg(1/2*(G*(i,j)+
G*(i+1,j+1)),1/2*(G*(i+1,j)+G*(i+2,j+1))) c= Int cell(G,i,j) \/ Int cell(G,i+1,
  j) \/ { 1/2*(G*(i+1,j)+G*(i+1,j+1)) }
proof
  assume that
A1: 1 <= j and
A2: j < width G and
A3: 1 <= i and
A4: i+1 < len G;
  set p1 = G*(i,j), p2 = G*(i+1,j), q2 = G*(i+1,j+1), q3 = G*(i+2,j+1), r = (
  p2`1-p1`1)/(q3`1-p1`1);
A5: i+1 >= 1 by NAT_1:11;
  set I1 = Int cell(G,i,j), I2 = Int cell(G,i+1,j);
  i <= i+1 by NAT_1:11;
  then
A6: i < len G by A4,XXREAL_0:2;
  then
A7: LSeg(1/2*(p1+q2),1/2*(p2+q2)) c= I1 \/ { 1/2*(p2+q2) } by A1,A2,A3,Th42;
  i < i+1 by XREAL_1:29;
  then p1`1 < p2`1 by A1,A2,A3,A4,GOBOARD5:3;
  then
A8: p2`1-p1`1 > 0 by XREAL_1:50;
A9: i+1+1 = i+(1+1);
  then
A10: i+2 >= 1 by NAT_1:11;
A11: i+(1+1) <= len G by A4,A9,NAT_1:13;
A12: j+1 >= 1 & j+1 <= width G by A2,NAT_1:11,13;
  then
A13: q2`2 = G*(1,j+1)`2 by A4,A5,GOBOARD5:1
    .= q3`2 by A11,A10,A12,GOBOARD5:1;
A14: q2`1 = G*(i+1,1)`1 by A4,A5,A12,GOBOARD5:2
    .= p2`1 by A1,A2,A4,A5,GOBOARD5:2;
  i+1 < i+2 by XREAL_1:6;
  then q2`1 < q3`1 by A5,A11,A12,GOBOARD5:3;
  then
A15: p2`1-p1`1 < q3`1-p1`1 by A14,XREAL_1:9;
  then
A16: r*(q3`1-p1`1) = p2`1-p1`1 by A8,XCMPLX_1:87;
  p1`2 = G*(1,j)`2 by A1,A2,A3,A6,GOBOARD5:1
    .= p2`2 by A1,A2,A4,A5,GOBOARD5:1;
  then
A17: (p2+q2)`2 = (1-r)*(p1`2+q2`2)+r*(p2`2+q3`2) by A13,Lm1
    .= (1-r)*(p1+q2)`2+r*(p2`2+q3`2) by Lm1
    .= (1-r)*(p1+q2)`2+r*(p2+q3)`2 by Lm1
    .= (1-r)*(p1+q2)`2+(r*(p2+q3))`2 by Lm3
    .= ((1-r)*(p1+q2))`2+(r*(p2+q3))`2 by Lm3
    .= ((1-r)*(p1+q2)+r*(p2+q3))`2 by Lm1;
  (p2+q2)`1 = p2`1+(r+(1-r))*q2`1 by Lm1
    .= (1-r)*(p1`1+q2`1)+r*(p2`1+q3`1) by A14,A16
    .= (1-r)*(p1`1+q2`1)+r*(p2+q3)`1 by Lm1
    .= (1-r)*(p1+q2)`1+r*(p2+q3)`1 by Lm1
    .= (1-r)*(p1+q2)`1+(r*(p2+q3))`1 by Lm3
    .= ((1-r)*(p1+q2))`1+(r*(p2+q3))`1 by Lm3
    .= ((1-r)*(p1+q2)+r*(p2+q3))`1 by Lm1;
  then (1-r)*(p1+q2)+r*(p2+q3) = |[(p2+q2)`1,(p2+q2)`2]| by A17,EUCLID:53
    .= p2+q2 by EUCLID:53;
  then
A18: 1/2*(p2+q2) = (1/2)*((1-r)*(p1+q2))+(1/2)*(r*(p2+q3)) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+q2)+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+q2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+q2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
  r < 1 by A15,A8,XREAL_1:189;
  then 1/2*(p2+q2) in LSeg(1/2*(p1+q2),1/2*(p2+q3)) by A15,A8,A18;
  then
A19: LSeg(1/2*(p1+q2),1/2*(p2+q3)) = LSeg(1/2*(p1+q2),1/2*(p2+q2)) \/ LSeg(1
  /2*(p2+q2),1/2*(p2+q3)) by TOPREAL1:5;
A20: I1 \/ I2 \/ { 1/2*(p2+q2) } = I1 \/ (I2 \/ ({ 1/2*(p2+q2) } \/ { 1/2*(
  p2+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p2+q2) } \/ { 1/2*(p2+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p2+q2) } \/ (I2 \/ { 1/2*(p2+q2) }) by XBOOLE_1:4;
  LSeg(1/2*(p2+q2),1/2*(p2+q3)) c= I2 \/ { 1/2*(p2+q2) } by A1,A2,A4,A5,A9,Th40
;
  hence thesis by A19,A7,A20,XBOOLE_1:13;
end;

theorem
  1 <= i & i < len G & 1 < width G implies LSeg(1/2*(G*(i,1)+G*(i+1,1))-
|[0,1]|,1/2*(G*(i,1)+G*(i+1,2))) c= Int cell(G,i,0) \/ Int cell(G,i,1) \/ { 1/2
  *(G*(i,1)+G*(i+1,1)) }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 < width G;
  set p1 = G*(i,1), q2 = G*(i+1,1), q3 = G*(i+1,2), r = 1/(1/2*(q3`2-p1`2)+1);
A4: i+1 >= 1 & i+1 <= len G by A2,NAT_1:11,13;
A5: 0+(1+1) <= width G by A3,NAT_1:13;
  then
A6: q2`1 = q3`1 by A4,GOBOARD5:2;
A7: q2`2 = G*(1,0+1)`2 by A3,A4,GOBOARD5:1
    .= p1`2 by A1,A2,A3,GOBOARD5:1;
  then p1`2 < q3`2 by A5,A4,GOBOARD5:4;
  then
A8: q3`2-p1`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`2-p1`2)+1 by XREAL_1:29,129;
  then
A9: r < 1 by XREAL_1:212;
  set I1 = Int cell(G,i,0), I2 = Int cell(G,i,1);
A10: LSeg(1/2*(p1+q2)-|[0,1]|,1/2*(p1+q2)) c= I1 \/ { 1/2*(p1+q2) } by A1,A2
,Th46;
A11: I1 \/ I2 \/ { 1/2*(p1+q2) } = I1 \/ (I2 \/ ({ 1/2*(p1+q2) } \/ { 1/2*(
  p1+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p1+q2) } \/ { 1/2*(p1+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p1+q2) } \/ (I2 \/ { 1/2*(p1+q2) }) by XBOOLE_1:4;
A12: ((1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[0,1]|)`1 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`1-((1-r)*|[0,1]|)`1 by Lm2
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1-|[(1-r)*0,(1-r)*1]|`1 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1-0 by EUCLID:52
    .= ((1-r)*((1/2)*q2))`1+(r*((1/2)*q3))`1 by Lm1
    .= (1-r)*((1/2)*q2)`1+(r*((1/2)*q3))`1 by Lm3
    .= (1-r)*((1/2)*q2)`1+r*((1/2)*q3)`1 by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3)`1 by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q2`1) by A6,Lm3
    .= ((1/2)*q2)`1 by Lm3;
A13: (1-r)*((1/2)*p1)+r*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*q3) = (1-r)*((1
  /2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1)+r*((1/2)*q3) by RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+(r*((1/2)*p1)+r*((1/2)*q3)) by
RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by
RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
A14: r*((1/2)*q3`2)-r*((1/2)*q2`2)+r = r*((1/2)*(q3`2-q2`2)+1)
    .= 1 by A7,A8,XCMPLX_1:106;
  ((1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[0,1]|)`2 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`2-((1-r)*|[0,1]|)`2 by Lm2
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2-|[(1-r)*0,(1-r)*1]|`2 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2-(1-r) by EUCLID:52
    .= ((1-r)*((1/2)*q2))`2+(r*((1/2)*q3))`2-(1-r) by Lm1
    .= (1-r)*((1/2)*q2)`2+(r*((1/2)*q3))`2-(1-r) by Lm3
    .= (1-r)*((1/2)*q2)`2+r*((1/2)*q3)`2-(1-r) by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3)`2-(1-r) by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3`2)-(1-r) by Lm3
    .= ((1/2)*q2)`2 by A14,Lm3;
  then
A15: (1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[0,1]| = |[(1/2*q2)`1,(1/2* q2 )`2
  ]| by A12,EUCLID:53
    .= 1/2*q2 by EUCLID:53;
  1/2*(p1+q2) = 1/2*p1+1/2*q2 by RLVECT_1:def 5
    .= (1-r+r)*((1/2)*p1)+1/2*q2 by RLVECT_1:def 8
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+1/2*q2 by RLVECT_1:def 6
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ ((1-r)*((1/2)*q2)+r*((1/2)*q3))-(1-r)*
  |[0,1]| by A15,RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ (1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[
  0,1]| by RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+(r*((1/2)*(p1+q3))-(1-r)*|[0,1]|) by A13,
RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+-((1-r)*|[0,1]|-r*((1/2)*(p1+q3))) by RLVECT_1:33
    .= (1-r)*((1/2)*(p1+q2))-((1-r)*|[0,1]|-r*((1/2)*(p1+q3)))
    .= (1-r)*((1/2)*(p1+q2))-(1-r)*|[0,1]|+r*((1/2)*(p1+q3)) by RLVECT_1:29
    .= (1-r)*((1/2)*(p1+q2)-|[0,1]|)+r*((1/2)*(p1+q3)) by RLVECT_1:34;
  then 1/2*(p1+q2) in LSeg(1/2*(p1+q2)-|[0,1]|,1/2*(p1+q3)) by A8,A9;
  then
A16: LSeg(1/2*(p1+q2)-|[0,1]|,1/2*(p1+q3)) = LSeg(1/2*(p1+q2)-|[0,1]|,1/2*(
  p1+q2)) \/ LSeg(1/2*(p1+q2),1/2*(p1+q3)) by TOPREAL1:5;
  0+1+1 = 0+(1+1);
  then LSeg(1/2*(p1+q2),1/2*(p1+q3)) c= I2 \/ { 1/2*(p1+q2) } by A1,A2,A3,Th43;
  hence thesis by A16,A10,A11,XBOOLE_1:13;
end;

theorem
  1 <= i & i < len G & 1 < width G implies LSeg(1/2*(G*(i,width G)+G*(i+
1,width G))+|[0,1]|, 1/2*(G*(i,width G)+G*(i+1,width G -' 1))) c= Int cell(G,i,
width G -'1) \/ Int cell(G,i,width G) \/ { 1/2*(G*(i,width G)+G*(i+1,width G))
  }
proof
  assume that
A1: 1 <= i and
A2: i < len G and
A3: 1 < width G;
  set I1 = Int cell(G,i,width G -'1), I2 = Int cell(G,i,width G);
  set p1 = G*(i,width G), q2 = G*(i+1,width G), q3 = G*(i+1,width G -' 1), r =
  1/(1/2*(p1`2-q3`2)+1);
A4: width G -'1 + 1 = width G by A3,XREAL_1:235;
  then
A5: 1 <= width G -'1 by A3,NAT_1:13;
A6: width G -'1 < width G by A4,NAT_1:13;
  then
  G*(i,width G)+G*(i+1,width G -' 1) = G*(i,width G -' 1)+G*(i+1,width G)
  by A1,A2,A4,A5,Th11;
  then
A7: LSeg(1/2*(p1+q2),1/2*(p1+q3)) c= I1 \/ { 1/2*(p1+q2) } by A1,A2,A4,A5,A6
,Th41;
A8: i+1 >= 1 & i+1 <= len G by A2,NAT_1:11,13;
  then
A9: q2`1 = G*(i+1,1)`1 by A3,GOBOARD5:2
    .= q3`1 by A5,A6,A8,GOBOARD5:2;
A10: q2`2 = G*(1,width G)`2 by A3,A8,GOBOARD5:1
    .= p1`2 by A1,A2,A3,GOBOARD5:1;
  then q3`2 < p1`2 by A5,A6,A8,GOBOARD5:4;
  then
A11: p1`2-q3`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(p1`2-q3`2)+1 by XREAL_1:29,129;
  then
A12: r < 1 by XREAL_1:212;
A13: ((1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[0,1]|)`1 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`1+((1-r)*|[0,1]|)`1 by Lm1
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1+|[(1-r)*0,(1-r)*1]|`1 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1+0 by EUCLID:52
    .= ((1-r)*((1/2)*q2))`1+(r*((1/2)*q3))`1 by Lm1
    .= (1-r)*((1/2)*q2)`1+(r*((1/2)*q3))`1 by Lm3
    .= (1-r)*((1/2)*q2)`1+r*((1/2)*q3)`1 by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3)`1 by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q2`1) by A9,Lm3
    .= ((1/2)*q2)`1 by Lm3;
A14: I1 \/ I2 \/ { 1/2*(p1+q2) } = I1 \/ (I2 \/ ({ 1/2*(p1+q2) } \/ { 1/2*(
  p1+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p1+q2) } \/ { 1/2*(p1+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p1+q2) } \/ (I2 \/ { 1/2*(p1+q2) }) by XBOOLE_1:4;
A15: (1-r)*((1/2)*p1)+r*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*q3) = (1-r)*((1
  /2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1)+r*((1/2)*q3) by RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+(r*((1/2)*p1)+r*((1/2)*q3)) by
RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by
RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
A16: r*((1/2)*q2`2)-r*((1/2)*q3`2)+r = r*((1/2)*(q2`2-q3`2)+1)
    .= 1 by A10,A11,XCMPLX_1:106;
  ((1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[0,1]|)`2 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`2+((1-r)*|[0,1]|)`2 by Lm1
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2+|[(1-r)*0,(1-r)*1]|`2 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2+(1-r) by EUCLID:52
    .= ((1-r)*((1/2)*q2))`2+(r*((1/2)*q3))`2+(1-r) by Lm1
    .= (1-r)*((1/2)*q2)`2+(r*((1/2)*q3))`2+(1-r) by Lm3
    .= (1-r)*((1/2)*q2)`2+r*((1/2)*q3)`2+(1-r) by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3)`2+(1-r) by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3`2)+(1-r) by Lm3
    .= ((1/2)*q2)`2 by A16,Lm3;
  then
A17: (1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[0,1]| = |[(1/2*q2)`1,(1/2* q2 )`2
  ]| by A13,EUCLID:53
    .= 1/2*q2 by EUCLID:53;
  1/2*(p1+q2) = 1/2*p1+1/2*q2 by RLVECT_1:def 5
    .= (1-r+r)*((1/2)*p1)+1/2*q2 by RLVECT_1:def 8
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+1/2*q2 by RLVECT_1:def 6
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ ((1-r)*((1/2)*q2)+r*((1/2)*q3))+(1-r)*
  |[0,1]| by A17,RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ (1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[
  0,1]| by RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+(1-r)*|[0,1]|+r*((1/2)*(p1+q3)) by A15,
RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2)+|[0,1]|)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
  then 1/2*(p1+q2) in LSeg(1/2*(p1+q2)+|[0,1]|,1/2*(p1+q3)) by A11,A12;
  then
A18: LSeg(1/2*(p1+q2)+|[0,1]|,1/2*(p1+q3)) = LSeg(1/2*(p1+q2)+|[0,1]|,1/2*(
  p1+q2)) \/ LSeg(1/2*(p1+q2),1/2*(p1+q3)) by TOPREAL1:5;
  LSeg(1/2*(p1+q2)+|[0,1]|,1/2*(p1+q2)) c= I2 \/ { 1/2*(p1+q2) } by A1,A2,Th47;
  hence thesis by A18,A7,A14,XBOOLE_1:13;
end;

theorem
  1 <= j & j < width G & 1 < len G implies LSeg(1/2*(G*(1,j)+G*(1,j+1))-
|[1,0]|,1/2*(G*(1,j)+G*(2,j+1))) c= Int cell(G,0,j) \/ Int cell(G,1,j) \/ { 1/2
  *(G*(1,j)+G*(1,j+1)) }
proof
  assume that
A1: 1 <= j and
A2: j < width G and
A3: 1 < len G;
  set p1 = G*(1,j), q2 = G*(1,j+1), q3 = G*(2,j+1), r = 1/(1/2*(q3`1-p1`1)+1);
A4: j+1 >= 1 & j+1 <= width G by A2,NAT_1:11,13;
A5: 0+(1+1) <= len G by A3,NAT_1:13;
  then
A6: q2`2 = q3`2 by A4,GOBOARD5:1;
A7: q2`1 = G*(1,1)`1 by A3,A4,GOBOARD5:2
    .= p1`1 by A1,A2,A3,GOBOARD5:2;
  then p1`1 < q3`1 by A5,A4,GOBOARD5:3;
  then
A8: q3`1-p1`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`1-p1`1)+1 by XREAL_1:29,129;
  then
A9: r < 1 by XREAL_1:212;
  set I1 = Int cell(G,0,j), I2 = Int cell(G,1,j);
A10: LSeg(1/2*(p1+q2)-|[1,0]|,1/2*(p1+q2)) c= I1 \/ { 1/2*(p1+q2) } by A1,A2
,Th44;
A11: I1 \/ I2 \/ { 1/2*(p1+q2) } = I1 \/ (I2 \/ ({ 1/2*(p1+q2) } \/ { 1/2*(
  p1+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p1+q2) } \/ { 1/2*(p1+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p1+q2) } \/ (I2 \/ { 1/2*(p1+q2) }) by XBOOLE_1:4;
A12: ((1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[1,0]|)`2 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`2-((1-r)*|[1,0]|)`2 by Lm2
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2-|[(1-r)*1,(1-r)*0]|`2 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2-0 by EUCLID:52
    .= ((1-r)*((1/2)*q2))`2+(r*((1/2)*q3))`2 by Lm1
    .= (1-r)*((1/2)*q2)`2+(r*((1/2)*q3))`2 by Lm3
    .= (1-r)*((1/2)*q2)`2+r*((1/2)*q3)`2 by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3)`2 by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q2`2) by A6,Lm3
    .= ((1/2)*q2)`2 by Lm3;
A13: (1-r)*((1/2)*p1)+r*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*q3) = (1-r)*((1
  /2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1)+r*((1/2)*q3) by RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+(r*((1/2)*p1)+r*((1/2)*q3)) by
RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by
RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
A14: r*((1/2)*q3`1)-r*((1/2)*q2`1)+r = r*((1/2)*(q3`1-q2`1)+1)
    .= 1 by A7,A8,XCMPLX_1:106;
  ((1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[1,0]|)`1 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`1-((1-r)*|[1,0]|)`1 by Lm2
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1-|[(1-r)*1,(1-r)*0]|`1 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1-(1-r) by EUCLID:52
    .= ((1-r)*((1/2)*q2))`1+(r*((1/2)*q3))`1-(1-r) by Lm1
    .= (1-r)*((1/2)*q2)`1+(r*((1/2)*q3))`1-(1-r) by Lm3
    .= (1-r)*((1/2)*q2)`1+r*((1/2)*q3)`1-(1-r) by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3)`1-(1-r) by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3`1)-(1-r) by Lm3
    .= ((1/2)*q2)`1 by A14,Lm3;
  then
A15: (1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[1,0]| = |[(1/2*q2)`1,(1/2* q2 )`2
  ]| by A12,EUCLID:53
    .= 1/2*q2 by EUCLID:53;
  1/2*(p1+q2) = 1/2*p1+1/2*q2 by RLVECT_1:def 5
    .= (1-r+r)*((1/2)*p1)+1/2*q2 by RLVECT_1:def 8
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+1/2*q2 by RLVECT_1:def 6
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ ((1-r)*((1/2)*q2)+r*((1/2)*q3))-(1-r)*
  |[1,0]| by A15,RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ (1-r)*((1/2)*q2)+r*((1/2)*q3)-(1-r)*|[
  1,0]| by RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+(r*((1/2)*(p1+q3))-(1-r)*|[1,0]|) by A13,
RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+-((1-r)*|[1,0]|-r*((1/2)*(p1+q3))) by RLVECT_1:33
    .= (1-r)*((1/2)*(p1+q2))-((1-r)*|[1,0]|-r*((1/2)*(p1+q3)))
    .= (1-r)*((1/2)*(p1+q2))-(1-r)*|[1,0]|+r*((1/2)*(p1+q3)) by RLVECT_1:29
    .= (1-r)*((1/2)*(p1+q2)-|[1,0]|)+r*((1/2)*(p1+q3)) by RLVECT_1:34;
  then 1/2*(p1+q2) in LSeg(1/2*(p1+q2)-|[1,0]|,1/2*(p1+q3)) by A8,A9;
  then
A16: LSeg(1/2*(p1+q2)-|[1,0]|,1/2*(p1+q3)) = LSeg(1/2*(p1+q2)-|[1,0]|,1/2*(
  p1+q2)) \/ LSeg(1/2*(p1+q2),1/2*(p1+q3)) by TOPREAL1:5;
  0+1+1 = 0+(1+1);
  then LSeg(1/2*(p1+q2),1/2*(p1+q3)) c= I2 \/ { 1/2*(p1+q2) } by A1,A2,A3,Th40;
  hence thesis by A16,A10,A11,XBOOLE_1:13;
end;

theorem
  1 <= j & j < width G & 1 < len G implies LSeg(1/2*(G*(len G,j)+G*(len
G,j+1))+|[1,0]|, 1/2*(G*(len G,j)+G*(len G -' 1,j+1))) c= Int cell(G,len G -' 1
  ,j) \/ Int cell(G,len G,j) \/ { 1/2*(G*(len G,j)+G*(len G,j+1)) }
proof
  assume that
A1: 1 <= j and
A2: j < width G and
A3: 1 < len G;
  set I1 = Int cell(G,len G -' 1,j), I2 = Int cell(G,len G,j);
  set p1 = G*(len G,j), q2 = G*(len G,j+1), q3 = G*(len G -' 1,j+1), r = 1/(1/
  2*(p1`1-q3`1)+1);
A4: len G -'1 + 1 = len G by A3,XREAL_1:235;
  then
A5: 1 <= len G -'1 by A3,NAT_1:13;
A6: len G -'1 < len G by A4,NAT_1:13;
  then
  G*(len G -' 1,j)+G*(len G,j+1) = G*(len G,j)+G* (len G -' 1,j+1) by A1,A2,A4
,A5,Th11;
  then
A7: LSeg(1/2*(p1+q2),1/2*(p1+q3)) c= I1 \/ { 1/2*(p1+q2) } by A1,A2,A4,A5,A6
,Th42;
A8: j+1 >= 1 & j+1 <= width G by A2,NAT_1:11,13;
  then
A9: q2`2 = G*(1,j+1)`2 by A3,GOBOARD5:1
    .= q3`2 by A5,A6,A8,GOBOARD5:1;
A10: q2`1 = G*(len G,1)`1 by A3,A8,GOBOARD5:2
    .= p1`1 by A1,A2,A3,GOBOARD5:2;
  then q3`1 < p1`1 by A5,A6,A8,GOBOARD5:3;
  then
A11: p1`1-q3`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(p1`1-q3`1)+1 by XREAL_1:29,129;
  then
A12: r < 1 by XREAL_1:212;
A13: ((1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[1,0]|)`2 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`2+((1-r)*|[1,0]|)`2 by Lm1
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2+|[(1-r)*1,(1-r)*0]|`2 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`2+0 by EUCLID:52
    .= ((1-r)*((1/2)*q2))`2+(r*((1/2)*q3))`2 by Lm1
    .= (1-r)*((1/2)*q2)`2+(r*((1/2)*q3))`2 by Lm3
    .= (1-r)*((1/2)*q2)`2+r*((1/2)*q3)`2 by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q3)`2 by Lm3
    .= (1-r)*((1/2)*q2`2)+r*((1/2)*q2`2) by A9,Lm3
    .= ((1/2)*q2)`2 by Lm3;
A14: I1 \/ I2 \/ { 1/2*(p1+q2) } = I1 \/ (I2 \/ ({ 1/2*(p1+q2) } \/ { 1/2*(
  p1+q2) })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { 1/2*(p1+q2) } \/ { 1/2*(p1+q2) }) by XBOOLE_1:4
    .= I1 \/ { 1/2*(p1+q2) } \/ (I2 \/ { 1/2*(p1+q2) }) by XBOOLE_1:4;
A15: (1-r)*((1/2)*p1)+r*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*q3) = (1-r)*((1
  /2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1)+r*((1/2)*q3) by RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+(r*((1/2)*p1)+r*((1/2)*q3)) by
RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+(1-r)*((1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by
RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*p1+(1/2)*q3) by RLVECT_1:def 5
    .= (1-r)*((1/2)*p1+(1/2)*q2)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5
    .= (1-r)*((1/2)*(p1+q2))+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
A16: r*((1/2)*q2`1)-r*((1/2)*q3`1)+r = r*((1/2)*(q2`1-q3`1)+1)
    .= 1 by A10,A11,XCMPLX_1:106;
  ((1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[1,0]|)`1 = ((1-r)*((1/2)*q2)+r*(
  (1/2)*q3))`1+((1-r)*|[1,0]|)`1 by Lm1
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1+|[(1-r)*1,(1-r)*0]|`1 by EUCLID:58
    .= ((1-r)*((1/2)*q2)+r*((1/2)*q3))`1+(1-r) by EUCLID:52
    .= ((1-r)*((1/2)*q2))`1+(r*((1/2)*q3))`1+(1-r) by Lm1
    .= (1-r)*((1/2)*q2)`1+(r*((1/2)*q3))`1+(1-r) by Lm3
    .= (1-r)*((1/2)*q2)`1+r*((1/2)*q3)`1+(1-r) by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3)`1+(1-r) by Lm3
    .= (1-r)*((1/2)*q2`1)+r*((1/2)*q3`1)+(1-r) by Lm3
    .= ((1/2)*q2)`1 by A16,Lm3;
  then
A17: (1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[1,0]| = |[(1/2*q2)`1,(1/2* q2 )`2
  ]| by A13,EUCLID:53
    .= 1/2*q2 by EUCLID:53;
  1/2*(p1+q2) = 1/2*p1+1/2*q2 by RLVECT_1:def 5
    .= (1-r+r)*((1/2)*p1)+1/2*q2 by RLVECT_1:def 8
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+1/2*q2 by RLVECT_1:def 6
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ ((1-r)*((1/2)*q2)+r*((1/2)*q3))+(1-r)*
  |[1,0]| by A17,RLVECT_1:def 3
    .= (1-r)*((1/2)*p1)+r*((1/2)*p1)+ (1-r)*((1/2)*q2)+r*((1/2)*q3)+(1-r)*|[
  1,0]| by RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2))+(1-r)*|[1,0]|+r*((1/2)*(p1+q3)) by A15,
RLVECT_1:def 3
    .= (1-r)*((1/2)*(p1+q2)+|[1,0]|)+r*((1/2)*(p1+q3)) by RLVECT_1:def 5;
  then 1/2*(p1+q2) in LSeg(1/2*(p1+q2)+|[1,0]|,1/2*(p1+q3)) by A11,A12;
  then
A18: LSeg(1/2*(p1+q2)+|[1,0]|,1/2*(p1+q3)) = LSeg(1/2*(p1+q2)+|[1,0]|,1/2*(
  p1+q2)) \/ LSeg(1/2*(p1+q2),1/2*(p1+q3)) by TOPREAL1:5;
  LSeg(1/2*(p1+q2)+|[1,0]|,1/2*(p1+q2)) c= I2 \/ { 1/2*(p1+q2) } by A1,A2,Th45;
  hence thesis by A18,A7,A14,XBOOLE_1:13;
end;

Lm7: 1/2+1/2 = 1;

theorem
  1 < len G & 1 <= j & j+1 < width G implies LSeg(1/2*(G*(1,j)+G*(1,j+1)
)-|[1,0]|,1/2*(G*(1,j+1)+G*(1,j+2))-|[1,0]|) c= Int cell(G,0,j) \/ Int cell(G,0
  ,j+1) \/ { G*(1,j+1)-|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 <= j and
A3: j+1 < width G;
  set p1 = G*(1,j), p2 = G*(1,j+1), q3 = G*(1,j+2), r = (p2`2-p1`2)/(q3`2-p1`2
  );
A4: j+1+1 = j+(1+1);
  then
A5: j+2 >= 1 by NAT_1:11;
A6: j+(1+1) <= width G by A3,A4,NAT_1:13;
  set I1 = Int cell(G,0,j), I2 = Int cell(G,0,j+1);
A7: I1 \/ I2 \/ { p2-|[1,0]| } = I1 \/ (I2 \/ ({ p2-|[1,0]| } \/ { p2-|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { p2-|[1,0]| } \/ { p2-|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { p2-|[1,0]| } \/ (I2 \/ { p2-|[1,0]| }) by XBOOLE_1:4;
A8: LSeg(1/2*(p2+q3)-|[1,0]|,p2-|[1,0]|) c= I2 \/ { p2-|[1,0]| } by A3,A4,Th48,
NAT_1:11;
  j < j+1 by XREAL_1:29;
  then p1`2 < p2`2 by A1,A2,A3,GOBOARD5:4;
  then
A9: p2`2-p1`2 > 0 by XREAL_1:50;
A10: j+1 >= 1 by NAT_1:11;
  then
A11: p2`1 = G*(1,1)`1 by A1,A3,GOBOARD5:2
    .= q3`1 by A1,A6,A5,GOBOARD5:2;
  j <= j+1 by NAT_1:11;
  then
A12: j < width G by A3,XXREAL_0:2;
  then p1`1 = G*(1,1)`1 by A1,A2,GOBOARD5:2
    .= p2`1 by A1,A3,A10,GOBOARD5:2;
  then
A13: 1*p2`1 = (1-r)*p1`1+r*q3`1 by A11
    .= ((1-r)*p1)`1+r*q3`1 by Lm3
    .= ((1-r)*p1)`1+(r*q3)`1 by Lm3
    .= ((1-r)*p1+r*q3)`1 by Lm1;
  j+1 < j+2 by XREAL_1:6;
  then p2`2 < q3`2 by A1,A10,A6,GOBOARD5:4;
  then
A14: p2`2-p1`2 < q3`2-p1`2 by XREAL_1:9;
  then r*(q3`2-p1`2) = p2`2-p1`2 by A9,XCMPLX_1:87;
  then p2`2 = (1-r)*p1`2 +r*q3`2;
  then 1*p2`2 = ((1-r)*p1)`2+r*q3`2 by Lm3
    .= ((1-r)*p1)`2+(r*q3)`2 by Lm3
    .= ((1-r)*p1+(r*q3))`2 by Lm1;
  then
A15: (1-r)*p1+r*q3 = |[p2`1,p2`2]| by A13,EUCLID:53
    .= p2 by EUCLID:53;
  p2 = 1*p2 by RLVECT_1:def 8
    .= 1/2*p2+1/2*p2 by Lm7,RLVECT_1:def 6
    .= 1/2*(((1-r)+r)*p2) + 1/2*((1-r)*p1+r*q3) by A15,RLVECT_1:def 8
    .= 1/2*((1-r)*p2+r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 6
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3)) by
RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+(1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+(1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= (1/2*((1-r)*p2)+1/2*((1-r)*p1))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 3
    .= 1/2*((1-r)*p2+(1-r)*p1)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*(p1+p2))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 7
    .= 1/2*(1-r)*(p1+p2)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2+r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*(p2+q3)) by RLVECT_1:def 5;
  then
A16: p2 = (1-r)*(1/2*(p1+p2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+p2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+p2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
A17: (1-r)*(1/2*(p1+p2)-|[1,0]|)+r*(1/2*(p2+q3)-|[1,0]|) = (1-r)*(1/2*(p1+p2
  ))-(1-r)*|[1,0]|+r*(1/2*(p2+q3)-|[1,0]|) by RLVECT_1:34
    .= (1-r)*(1/2*(p1+p2))-(1-r)*|[1,0]|+(r*(1/2*(p2+q3))-r*|[1,0]|) by
RLVECT_1:34
    .= r*(1/2*(p2+q3))+((1-r)*(1/2*(p1+p2))-(1-r)*|[1,0]|)-r*|[1,0]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-(1-r)*|[1,0]|-r*|[1,0]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-((1-r)*|[1,0]|+r*|[1,0]|) by
RLVECT_1:27
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-((1-r)+r)*|[1,0]| by RLVECT_1:def 6
    .= p2-|[1,0]| by A16,RLVECT_1:def 8;
  r < 1 by A14,A9,XREAL_1:189;
  then p2-|[1,0]| in LSeg(1/2*(p1+p2)-|[1,0]|,1/2*(p2+q3)-|[1,0]|) by A14,A9
,A17;
  then
A18: LSeg(1/2*(p1+p2)-|[1,0]|,1/2*(p2+q3)-|[1,0]|) = LSeg(1/2*(p1+p2)-|[1,0
  ]|,p2-|[1,0]|) \/ LSeg(p2-|[1,0]|,1/2*(p2+q3)-|[1,0]|) by TOPREAL1:5;
  LSeg(1/2*(p1+p2)-|[1,0]|,p2-|[1,0]|) c= I1 \/ { p2-|[1,0]| } by A2,A12,Th49;
  hence thesis by A18,A8,A7,XBOOLE_1:13;
end;

theorem
  1 < len G & 1 <= j & j+1 < width G implies LSeg(1/2*(G*(len G,j)+G*(
len G,j+1))+|[1,0]|, 1/2*(G*(len G,j+1)+G*(len G,j+2))+|[1,0]|) c= Int cell(G,
  len G,j) \/ Int cell(G,len G,j+1) \/ { G*(len G,j+1)+|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 <= j and
A3: j+1 < width G;
  set p1 = G*(len G,j), p2 = G*(len G,j+1), q3 = G*(len G,j+2), r = (p2`2-p1`2
  )/(q3`2-p1`2);
A4: j+1+1 = j+(1+1);
  then
A5: j+2 >= 1 by NAT_1:11;
A6: j+(1+1) <= width G by A3,A4,NAT_1:13;
  set I1 = Int cell(G,len G,j), I2 = Int cell(G,len G,j+1);
A7: I1 \/ I2 \/ { p2+|[1,0]| } = I1 \/ (I2 \/ ({ p2+|[1,0]| } \/ { p2+|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { p2+|[1,0]| } \/ { p2+|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { p2+|[1,0]| } \/ (I2 \/ { p2+|[1,0]| }) by XBOOLE_1:4;
A8: LSeg(1/2*(p2+q3)+|[1,0]|,p2+|[1,0]|) c= I2 \/ { p2+|[1,0]| } by A3,A4,Th50,
NAT_1:11;
  j < j+1 by XREAL_1:29;
  then p1`2 < p2`2 by A1,A2,A3,GOBOARD5:4;
  then
A9: p2`2-p1`2 > 0 by XREAL_1:50;
A10: j+1 >= 1 by NAT_1:11;
  then
A11: p2`1 = G*(len G,1)`1 by A1,A3,GOBOARD5:2
    .= q3`1 by A1,A6,A5,GOBOARD5:2;
  j <= j+1 by NAT_1:11;
  then
A12: j < width G by A3,XXREAL_0:2;
  then p1`1 = G*(len G,1)`1 by A1,A2,GOBOARD5:2
    .= p2`1 by A1,A3,A10,GOBOARD5:2;
  then
A13: 1*p2`1 = (1-r)*p1`1+r*q3`1 by A11
    .= ((1-r)*p1)`1+r*q3`1 by Lm3
    .= ((1-r)*p1)`1+(r*q3)`1 by Lm3
    .= ((1-r)*p1+r*q3)`1 by Lm1;
  j+1 < j+2 by XREAL_1:6;
  then p2`2 < q3`2 by A1,A10,A6,GOBOARD5:4;
  then
A14: p2`2-p1`2 < q3`2-p1`2 by XREAL_1:9;
  then r*(q3`2-p1`2) = p2`2-p1`2 by A9,XCMPLX_1:87;
  then p2`2 = (1-r)*p1`2 +r*q3`2;
  then 1*p2`2 = ((1-r)*p1)`2+r*q3`2 by Lm3
    .= ((1-r)*p1)`2+(r*q3)`2 by Lm3
    .= ((1-r)*p1+(r*q3))`2 by Lm1;
  then
A15: (1-r)*p1+r*q3 = |[p2`1,p2`2]| by A13,EUCLID:53
    .= p2 by EUCLID:53;
  p2 = 1*p2 by RLVECT_1:def 8
    .= 1/2*p2+1/2*p2 by Lm7,RLVECT_1:def 6
    .= 1/2*(((1-r)+r)*p2) + 1/2*((1-r)*p1+r*q3) by A15,RLVECT_1:def 8
    .= 1/2*((1-r)*p2+r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 6
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3)) by
RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+(1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+(1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= (1/2*((1-r)*p2)+1/2*((1-r)*p1))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 3
    .= 1/2*((1-r)*p2+(1-r)*p1)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*(p1+p2))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 7;
  then
A16: p2 = 1/2*(1-r)*(p1+p2)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2+r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*(p2+q3)) by RLVECT_1:def 5
    .= (1-r)*(1/2*(p1+p2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+p2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+p2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
A17: (1-r)*(1/2*(p1+p2)+|[1,0]|)+r*(1/2*(p2+q3)+|[1,0]|) = (1-r)*(1/2*(p1+p2
  ))+(1-r)*|[1,0]|+r*(1/2*(p2+q3)+|[1,0]|) by RLVECT_1:def 5
    .= (1-r)*(1/2*(p1+p2))+(1-r)*|[1,0]|+(r*(1/2*(p2+q3))+r*|[1,0]|) by
RLVECT_1:def 5
    .= r*(1/2*(p2+q3))+((1-r)*(1/2*(p1+p2))+(1-r)*|[1,0]|)+r*|[1,0]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+(1-r)*|[1,0]|+r*|[1,0]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+((1-r)*|[1,0]|+r*|[1,0]|) by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+((1-r)+r)*|[1,0]| by RLVECT_1:def 6
    .= p2+|[1,0]| by A16,RLVECT_1:def 8;
  r < 1 by A14,A9,XREAL_1:189;
  then p2+|[1,0]| in LSeg(1/2*(p1+p2)+|[1,0]|,1/2*(p2+q3)+|[1,0]|) by A14,A9
,A17;
  then
A18: LSeg(1/2*(p1+p2)+|[1,0]|,1/2*(p2+q3)+|[1,0]|) = LSeg(1/2*(p1+p2)+|[1,0
  ]|,p2+|[1,0]|) \/ LSeg(p2+|[1,0]|,1/2*(p2+q3)+|[1,0]|) by TOPREAL1:5;
  LSeg(1/2*(p1+p2)+|[1,0]|,p2+|[1,0]|) c= I1 \/ { p2+|[1,0]| } by A2,A12,Th51;
  hence thesis by A18,A8,A7,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 <= i & i+1 < len G implies LSeg(1/2*(G*(i,1)+G*(i+1,1)
)-|[0,1]|,1/2*(G*(i+1,1)+G*(i+2,1))-|[0,1]|) c= Int cell(G,i,0) \/ Int cell(G,i
  +1,0) \/ { G*(i+1,1)-|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 <= i and
A3: i+1 < len G;
  set p1 = G*(i,1), p2 = G*(i+1,1), q3 = G*(i+2,1), r = (p2`1-p1`1)/(q3`1-p1`1
  );
A4: i+1+1 = i+(1+1);
  then
A5: i+2 >= 1 by NAT_1:11;
A6: i+(1+1) <= len G by A3,A4,NAT_1:13;
  set I1 = Int cell(G,i,0), I2 = Int cell(G,i+1,0);
A7: I1 \/ I2 \/ { p2-|[0,1]| } = I1 \/ (I2 \/ ({ p2-|[0,1]| } \/ { p2-|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { p2-|[0,1]| } \/ { p2-|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { p2-|[0,1]| } \/ (I2 \/ { p2-|[0,1]| }) by XBOOLE_1:4;
A8: LSeg(1/2*(p2+q3)-|[0,1]|,p2-|[0,1]|) c= I2 \/ { p2-|[0,1]| } by A3,A4,Th52,
NAT_1:11;
  i < i+1 by XREAL_1:29;
  then p1`1 < p2`1 by A1,A2,A3,GOBOARD5:3;
  then
A9: p2`1-p1`1 > 0 by XREAL_1:50;
A10: i+1 >= 1 by NAT_1:11;
  then
A11: p2`2 = G*(1,1)`2 by A1,A3,GOBOARD5:1
    .= q3`2 by A1,A6,A5,GOBOARD5:1;
  i <= i+1 by NAT_1:11;
  then
A12: i < len G by A3,XXREAL_0:2;
  then p1`2 = G*(1,1)`2 by A1,A2,GOBOARD5:1
    .= p2`2 by A1,A3,A10,GOBOARD5:1;
  then
A13: 1*p2`2 = (1-r)*p1`2+r*q3`2 by A11
    .= ((1-r)*p1)`2+r*q3`2 by Lm3
    .= ((1-r)*p1)`2+(r*q3)`2 by Lm3
    .= ((1-r)*p1+r*q3)`2 by Lm1;
  i+1 < i+2 by XREAL_1:6;
  then p2`1 < q3`1 by A1,A10,A6,GOBOARD5:3;
  then
A14: p2`1-p1`1 < q3`1-p1`1 by XREAL_1:9;
  then r*(q3`1-p1`1) = p2`1-p1`1 by A9,XCMPLX_1:87;
  then p2`1 = (1-r)*p1`1 +r*q3`1;
  then 1*p2`1 = ((1-r)*p1)`1+r*q3`1 by Lm3
    .= ((1-r)*p1)`1+(r*q3)`1 by Lm3
    .= ((1-r)*p1+(r*q3))`1 by Lm1;
  then
A15: (1-r)*p1+r*q3 = |[p2`1,p2`2]| by A13,EUCLID:53
    .= p2 by EUCLID:53;
  p2 = 1*p2 by RLVECT_1:def 8
    .= 1/2*p2+1/2*p2 by Lm7,RLVECT_1:def 6
    .= 1/2*(((1-r)+r)*p2) + 1/2*((1-r)*p1+r*q3) by A15,RLVECT_1:def 8
    .= 1/2*((1-r)*p2+r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 6
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3)) by
RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+(1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+(1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= (1/2*((1-r)*p2)+1/2*((1-r)*p1))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 3
    .= 1/2*((1-r)*p2+(1-r)*p1)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*(p1+p2))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 7
    .= 1/2*(1-r)*(p1+p2)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2+r*q3) by RLVECT_1:def 5;
  then
A16: p2 = 1/2*(1-r)*(p1+p2)+1/2*(r*(p2+q3)) by RLVECT_1:def 5
    .= (1-r)*(1/2*(p1+p2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+p2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+p2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
A17: (1-r)*(1/2*(p1+p2)-|[0,1]|)+r*(1/2*(p2+q3)-|[0,1]|) = (1-r)*(1/2*(p1+p2
  ))-(1-r)*|[0,1]|+r*(1/2*(p2+q3)-|[0,1]|) by RLVECT_1:34
    .= (1-r)*(1/2*(p1+p2))-(1-r)*|[0,1]|+(r*(1/2*(p2+q3))-r*|[0,1]|) by
RLVECT_1:34
    .= r*(1/2*(p2+q3))+((1-r)*(1/2*(p1+p2))-(1-r)*|[0,1]|)-r*|[0,1]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-(1-r)*|[0,1]|-r*|[0,1]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-((1-r)*|[0,1]|+r*|[0,1]|) by
RLVECT_1:27
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))-((1-r)+r)*|[0,1]| by RLVECT_1:def 6
    .= p2-|[0,1]| by A16,RLVECT_1:def 8;
  r < 1 by A14,A9,XREAL_1:189;
  then p2-|[0,1]| in LSeg(1/2*(p1+p2)-|[0,1]|,1/2*(p2+q3)-|[0,1]|) by A14,A9
,A17;
  then
A18: LSeg(1/2*(p1+p2)-|[0,1]|,1/2*(p2+q3)-|[0,1]|) = LSeg(1/2*(p1+p2)-|[0,1
  ]|,p2-|[0,1]|) \/ LSeg(p2-|[0,1]|,1/2*(p2+q3)-|[0,1]|) by TOPREAL1:5;
  LSeg(1/2*(p1+p2)-|[0,1]|,p2-|[0,1]|) c= I1 \/ { p2-|[0,1]| } by A2,A12,Th53;
  hence thesis by A18,A8,A7,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 <= i & i+1 < len G implies LSeg(1/2*(G*(i,width G)+G*(
  i+1,width G))+|[0,1]|, 1/2*(G*(i+1,width G)+G*(i+2,width G))+|[0,1]|) c= Int
  cell(G,i,width G) \/ Int cell(G,i+1,width G) \/ { G*(i+1,width G)+|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 <= i and
A3: i+1 < len G;
  set p1 = G*(i,width G), p2 = G*(i+1,width G), q3 = G*(i+2,width G), r = (p2
  `1-p1`1)/(q3`1-p1`1);
A4: i+1+1 = i+(1+1);
  then
A5: i+2 >= 1 by NAT_1:11;
A6: i+(1+1) <= len G by A3,A4,NAT_1:13;
  set I1 = Int cell(G,i,width G), I2 = Int cell(G,i+1,width G);
A7: I1 \/ I2 \/ { p2+|[0,1]| } = I1 \/ (I2 \/ ({ p2+|[0,1]| } \/ { p2+|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { p2+|[0,1]| } \/ { p2+|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { p2+|[0,1]| } \/ (I2 \/ { p2+|[0,1]| }) by XBOOLE_1:4;
A8: LSeg(1/2*(p2+q3)+|[0,1]|,p2+|[0,1]|) c= I2 \/ { p2+|[0,1]| } by A3,A4,Th54,
NAT_1:11;
  i < i+1 by XREAL_1:29;
  then p1`1 < p2`1 by A1,A2,A3,GOBOARD5:3;
  then
A9: p2`1-p1`1 > 0 by XREAL_1:50;
A10: i+1 >= 1 by NAT_1:11;
  then
A11: p2`2 = G*(1,width G)`2 by A1,A3,GOBOARD5:1
    .= q3`2 by A1,A6,A5,GOBOARD5:1;
  i <= i+1 by NAT_1:11;
  then
A12: i < len G by A3,XXREAL_0:2;
  then p1`2 = G*(1,width G)`2 by A1,A2,GOBOARD5:1
    .= p2`2 by A1,A3,A10,GOBOARD5:1;
  then
A13: 1*p2`2 = (1-r)*p1`2+r*q3`2 by A11
    .= ((1-r)*p1)`2+r*q3`2 by Lm3
    .= ((1-r)*p1)`2+(r*q3)`2 by Lm3
    .= ((1-r)*p1+r*q3)`2 by Lm1;
  i+1 < i+2 by XREAL_1:6;
  then p2`1 < q3`1 by A1,A10,A6,GOBOARD5:3;
  then
A14: p2`1-p1`1 < q3`1-p1`1 by XREAL_1:9;
  then r*(q3`1-p1`1) = p2`1-p1`1 by A9,XCMPLX_1:87;
  then p2`1 = (1-r)*p1`1 +r*q3`1;
  then 1*p2`1 = ((1-r)*p1)`1+r*q3`1 by Lm3
    .= ((1-r)*p1)`1+(r*q3)`1 by Lm3
    .= ((1-r)*p1+(r*q3))`1 by Lm1;
  then
A15: (1-r)*p1+r*q3 = |[p2`1,p2`2]| by A13,EUCLID:53
    .= p2 by EUCLID:53;
  p2 = 1*p2 by RLVECT_1:def 8
    .= 1/2*p2+1/2*p2 by Lm7,RLVECT_1:def 6
    .= 1/2*(((1-r)+r)*p2) + 1/2*((1-r)*p1+r*q3) by A15,RLVECT_1:def 8
    .= 1/2*((1-r)*p2+r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 6
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + 1/2*((1-r)*p1+r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3)) by
RLVECT_1:def 5
    .= 1/2*((1-r)*p2)+(1/2*(r*p2) + (1/2*((1-r)*p1)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+(1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3))) by
RLVECT_1:def 3
    .= 1/2*((1-r)*p2)+1/2*((1-r)*p1)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= (1/2*((1-r)*p2)+1/2*((1-r)*p1))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 3
    .= 1/2*((1-r)*p2+(1-r)*p1)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*((1-r)*(p1+p2))+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2)+1/2*(r*q3) by RLVECT_1:def 7;
  then
A16: p2 = 1/2*(1-r)*(p1+p2)+(1/2*(r*p2)+1/2*(r*q3)) by RLVECT_1:def 3
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*p2+r*q3) by RLVECT_1:def 5
    .= 1/2*(1-r)*(p1+p2)+1/2*(r*(p2+q3)) by RLVECT_1:def 5
    .= (1-r)*(1/2*(p1+p2))+1/2*(r*(p2+q3)) by RLVECT_1:def 7
    .= (1-r)*(1/2*(p1+p2))+1/2*r*(p2+q3) by RLVECT_1:def 7
    .= (1-r)*((1/2)*(p1+p2))+r*((1/2)*(p2+q3)) by RLVECT_1:def 7;
A17: (1-r)*(1/2*(p1+p2)+|[0,1]|)+r*(1/2*(p2+q3)+|[0,1]|) = (1-r)*(1/2*(p1+p2
  ))+(1-r)*|[0,1]|+r*(1/2*(p2+q3)+|[0,1]|) by RLVECT_1:def 5
    .= (1-r)*(1/2*(p1+p2))+(1-r)*|[0,1]|+(r*(1/2*(p2+q3))+r*|[0,1]|) by
RLVECT_1:def 5
    .= r*(1/2*(p2+q3))+((1-r)*(1/2*(p1+p2))+(1-r)*|[0,1]|)+r*|[0,1]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+(1-r)*|[0,1]|+r*|[0,1]| by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+((1-r)*|[0,1]|+r*|[0,1]|) by
RLVECT_1:def 3
    .= r*(1/2*(p2+q3))+(1-r)*(1/2*(p1+p2))+((1-r)+r)*|[0,1]| by RLVECT_1:def 6
    .= p2+|[0,1]| by A16,RLVECT_1:def 8;
  r < 1 by A14,A9,XREAL_1:189;
  then p2+|[0,1]| in LSeg(1/2*(p1+p2)+|[0,1]|,1/2*(p2+q3)+|[0,1]|) by A14,A9
,A17;
  then
A18: LSeg(1/2*(p1+p2)+|[0,1]|,1/2*(p2+q3)+|[0,1]|) = LSeg(1/2*(p1+p2)+|[0,1
  ]|,p2+|[0,1]|) \/ LSeg(p2+|[0,1]|,1/2*(p2+q3)+|[0,1]|) by TOPREAL1:5;
  LSeg(1/2*(p1+p2)+|[0,1]|,p2+|[0,1]|) c= I1 \/ { p2+|[0,1]| } by A2,A12,Th55;
  hence thesis by A18,A8,A7,XBOOLE_1:13;
end;

theorem
  1 < len G & 1 < width G implies LSeg(G*(1,1)-|[1,1]|,1/2*(G*(1,1)+G*(1
  ,2))-|[1,0]|) c= Int cell(G,0,0) \/ Int cell(G,0,1) \/ { G*(1,1)-|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 < width G;
  set q2 = G*(1,1), q3 = G*(1,2), r = 1/(1/2*(q3`2-q2`2)+1);
A3: 0+(1+1) <= width G by A2,NAT_1:13;
  then
A4: q2`1 = q3`1 by A1,GOBOARD5:2;
  q2`2 < q3`2 by A1,A3,GOBOARD5:4;
  then
A5: q3`2-q2`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`2-q2`2)+1 by XREAL_1:29,129;
  then
A6: r < 1 by XREAL_1:212;
A7: ((1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[1,0]|))`1 = ((1-r)*(q2-|[1,1]|))`1
  +(r*(1/2*(q2+q3)-|[1,0]|))`1 by Lm1
    .= (1-r)*(q2-|[1,1]|)`1+(r*(1/2*(q2+q3)-|[1,0]|))`1 by Lm3
    .= (1-r)*(q2-|[1,1]|)`1+r*(1/2*(q2+q3)-|[1,0]|)`1 by Lm3
    .= (1-r)*(q2`1-|[1,1]|`1)+r*(1/2*(q2+q3)-|[1,0]|)`1 by Lm2
    .= (1-r)*(q2`1-|[1,1]|`1)+r*((1/2*(q2+q3))`1-|[1,0]|`1) by Lm2
    .= (1-r)*(q2`1-1)+r*((1/2*(q2+q3))`1-|[1,0]|`1) by EUCLID:52
    .= (1-r)*q2`1-(1-r)*1+r*((1/2*(q2+q3))`1-1) by EUCLID:52
    .= (1-r)*q2`1+r*(1/2*(q2+q3))`1-((1-r)+r)
    .= (1-r)*q2`1+r*(1/2*(q2+q3)`1)-1 by Lm3
    .= (1-r)*q2`1+r*(1/2*(q2`1+q2`1))-1 by A4,Lm1
    .= q2`1-|[1,0]|`1 by EUCLID:52
    .= (q2-|[1,0]|)`1 by Lm2;
A8: r*((1/2)*q3`2)-r*((1/2)*q2`2)+r = r*((1/2)*(q3`2-q2`2)+1)
    .= 1 by A5,XCMPLX_1:106;
  ((1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[1,0]|))`2 = ((1-r)*(q2-|[1,1]|))`2
  +(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm1
    .= ((1-r)*q2-(1-r)*|[1,1]|)`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by RLVECT_1:34
    .= ((1-r)*q2)`2-((1-r)*|[1,1]|)`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm2
    .= ((1-r)*q2)`2-(1-r)*|[1,1]|`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm3
    .= ((1-r)*q2)`2-(1-r)*1+(r*(1/2*(q2+q3)-|[1,0]|))`2 by EUCLID:52
    .= (1-r)*q2`2-(1-r)*1+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm3
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2+q3)-|[1,0]|)`2 by Lm3
    .= (1-r)*q2`2-(1-r)+r*((1/2*(q2+q3))`2-|[1,0]|`2) by Lm2
    .= (1-r)*q2`2-(1-r)+r*((1/2*(q2+q3))`2-0) by EUCLID:52
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2+q3)`2) by Lm3
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2`2+q3`2)) by Lm1
    .= q2`2-0 by A8
    .= q2`2-|[1,0]|`2 by EUCLID:52
    .= (q2-|[1,0]|)`2 by Lm2;
  then
  (1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[1,0]|) = |[(q2-|[1,0]|)`1,(q2-|[1,0
  ]|)`2]| by A7,EUCLID:53
    .= q2-|[1,0]| by EUCLID:53;
  then q2-|[1,0]| in LSeg(q2-|[1,1]|,1/2*(q2+q3)-|[1,0]|) by A5,A6;
  then
A9: LSeg(q2-|[1,1]|,1/2*(q2+q3)-|[1,0]|) = LSeg(q2-|[1,1]|,q2-|[1,0]|) \/
  LSeg(q2-|[1,0]|,1/2*(q2+q3)-|[1,0]|) by TOPREAL1:5;
  set I1 = Int cell(G,0,0), I2 = Int cell(G,0,1);
  0+1+1 = 0+(1+1);
  then
A10: LSeg(q2-|[1,0]|,1/2*(q2+q3)-|[1,0]|) c= I2 \/ { q2-|[1,0]| } by A2,Th48;
A11: I1 \/ I2 \/ { q2-|[1,0]| } = I1 \/ (I2 \/ ({ q2-|[1,0]| } \/ { q2-|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2-|[1,0]| } \/ { q2-|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { q2-|[1,0]| } \/ (I2 \/ { q2-|[1,0]| }) by XBOOLE_1:4;
  LSeg(q2-|[1,1]|,q2-|[1,0]|) c= I1 \/ { q2-|[1,0]| } by Th56;
  hence thesis by A9,A10,A11,XBOOLE_1:13;
end;

theorem
  1 < len G & 1 < width G implies LSeg(G*(len G,1)+|[1,-1]|,1/2*(G*(len
G,1)+G*(len G,2))+|[1,0]|) c= Int cell(G,len G,0) \/ Int cell(G,len G,1) \/ { G
  *(len G,1)+|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 < width G;
  set q2 = G*(len G,1), q3 = G*(len G,2), r = 1/(1/2*(q3`2-q2`2)+1);
A3: 0+(1+1) <= width G by A2,NAT_1:13;
  then
A4: q2`1 = q3`1 by A1,GOBOARD5:2;
  q2`2 < q3`2 by A1,A3,GOBOARD5:4;
  then
A5: q3`2-q2`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`2-q2`2)+1 by XREAL_1:29,129;
  then
A6: r < 1 by XREAL_1:212;
A7: ((1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)+|[1,0]|))`1 = ((1-r)*(q2+|[1,-1]|))
  `1+(r*(1/2*(q2+q3)+|[1,0]|))`1 by Lm1
    .= (1-r)*(q2+|[1,-1]|)`1+(r*(1/2*(q2+q3)+|[1,0]|))`1 by Lm3
    .= (1-r)*(q2+|[1,-1]|)`1+r*(1/2*(q2+q3)+|[1,0]|)`1 by Lm3
    .= (1-r)*(q2`1+|[1,-1]|`1)+r*(1/2*(q2+q3)+|[1,0]|)`1 by Lm1
    .= (1-r)*(q2`1+|[1,-1]|`1)+r*((1/2*(q2+q3))`1+|[1,0]|`1) by Lm1
    .= (1-r)*(q2`1+1)+r*((1/2*(q2+q3))`1+|[1,0]|`1) by EUCLID:52
    .= (1-r)*q2`1+(1-r)*1+r*((1/2*(q2+q3))`1+1) by EUCLID:52
    .= (1-r)*q2`1+r*(1/2*(q2+q3))`1+((1-r)+r)
    .= (1-r)*q2`1+r*(1/2*(q2+q3)`1)+1 by Lm3
    .= (1-r)*q2`1+r*(1/2*(q2`1+q2`1))+1 by A4,Lm1
    .= q2`1+|[1,0]|`1 by EUCLID:52
    .= (q2+|[1,0]|)`1 by Lm1;
A8: r*((1/2)*q3`2)-r*((1/2)*q2`2)+r = r*((1/2)*(q3`2-q2`2)+1)
    .= 1 by A5,XCMPLX_1:106;
  ((1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)+|[1,0]|))`2 = ((1-r)*(q2+|[1,-1]|))
  `2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm1
    .= ((1-r)*q2+(1-r)*|[1,-1]|)`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by
RLVECT_1:def 5
    .= ((1-r)*q2)`2+((1-r)*|[1,-1]|)`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm1
    .= ((1-r)*q2)`2+(1-r)*|[1,-1]|`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm3
    .= ((1-r)*q2)`2+(1-r)*(-1)+(r*(1/2*(q2+q3)+|[1,0]|))`2 by EUCLID:52
    .= (1-r)*q2`2+-(1-r)+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm3
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2+q3)+|[1,0]|)`2 by Lm3
    .= (1-r)*q2`2-(1-r)+r*((1/2*(q2+q3))`2+|[1,0]|`2) by Lm1
    .= (1-r)*q2`2-(1-r)+r*((1/2*(q2+q3))`2+0) by EUCLID:52
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2+q3)`2) by Lm3
    .= (1-r)*q2`2-(1-r)+r*(1/2*(q2`2+q3`2)) by Lm1
    .= q2`2+0 by A8
    .= q2`2+|[1,0]|`2 by EUCLID:52
    .= (q2+|[1,0]|)`2 by Lm1;
  then
  (1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)+|[1,0]|) = |[(q2+|[1,0]|)`1,(q2+|[1,
  0]|)`2]| by A7,EUCLID:53
    .= q2+|[1,0]| by EUCLID:53;
  then q2+|[1,0]| in LSeg(q2+|[1,-1]|,1/2*(q2+q3)+|[1,0]|) by A5,A6;
  then
A9: LSeg(q2+|[1,-1]|,1/2*(q2+q3)+|[1,0]|) = LSeg(q2+|[1,-1]|,q2+|[1,0]|) \/
  LSeg(q2+|[1,0]|,1/2*(q2+q3)+|[1,0]|) by TOPREAL1:5;
  set I1 = Int cell(G,len G,0), I2 = Int cell(G,len G,1);
  0+1+1 = 0+(1+1);
  then
A10: LSeg(q2+|[1,0]|,1/2*(q2+q3)+|[1,0]|) c= I2 \/ { q2+|[1,0]| } by A2,Th50;
A11: I1 \/ I2 \/ { q2+|[1,0]| } = I1 \/ (I2 \/ ({ q2+|[1,0]| } \/ { q2+|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2+|[1,0]| } \/ { q2+|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { q2+|[1,0]| } \/ (I2 \/ { q2+|[1,0]| }) by XBOOLE_1:4;
  LSeg(q2+|[1,-1]|,q2+|[1,0]|) c= I1 \/ { q2+|[1,0]| } by Th57;
  hence thesis by A9,A10,A11,XBOOLE_1:13;
end;

theorem
  1 < len G & 1 < width G implies LSeg(G*(1,width G)+|[-1,1]|,1/2*(G*(1,
width G)+G* (1,width G -' 1))-|[1,0]|) c= Int cell(G,0,width G) \/ Int cell(G,0
  ,width G -' 1) \/ { G*(1,width G)-|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 < width G;
  set q2 = G*(1,width G), q3 = G*(1,width G -' 1), r = 1/(1/2*(q2`2-q3`2)+1);
A3: width G -' 1 + 1 = width G by A2,XREAL_1:235;
  then
A4: width G -' 1 >= 1 by A2,NAT_1:13;
A5: width G -'1 < width G by A3,NAT_1:13;
  then q3`2 < q2`2 by A1,A4,GOBOARD5:4;
  then
A6: q2`2-q3`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(q2`2-q3`2)+1 by XREAL_1:29,129;
  then
A7: r < 1 by XREAL_1:212;
A8: q2`1 = G*(1,1)`1 by A1,A2,GOBOARD5:2
    .= q3`1 by A1,A4,A5,GOBOARD5:2;
A9: ((1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)-|[1,0]|))`1 = ((1-r)*(q2+|[-1,1]|))
  `1+(r*(1/2*(q2+q3)-|[1,0]|))`1 by Lm1
    .= (1-r)*(q2+|[-1,1]|)`1+(r*(1/2*(q2+q3)-|[1,0]|))`1 by Lm3
    .= (1-r)*(q2+|[-1,1]|)`1+r*(1/2*(q2+q3)-|[1,0]|)`1 by Lm3
    .= (1-r)*(q2`1+|[-1,1]|`1)+r*(1/2*(q2+q3)-|[1,0]|)`1 by Lm1
    .= (1-r)*(q2`1+|[-1,1]|`1)+r*((1/2*(q2+q3))`1-|[1,0]|`1) by Lm2
    .= (1-r)*(q2`1+-1)+r*((1/2*(q2+q3))`1-|[1,0]|`1) by EUCLID:52
    .= (1-r)*(q2`1-1)+r*((1/2*(q2+q3))`1-1) by EUCLID:52
    .= (1-r)*q2`1+r*(1/2*(q2+q3))`1-1
    .= (1-r)*q2`1+r*(1/2*(q2+q3)`1)-1 by Lm3
    .= (1-r)*q2`1+r*(1/2*(q2`1+q2`1))-1 by A8,Lm1
    .= q2`1-|[1,0]|`1 by EUCLID:52
    .= (q2-|[1,0]|)`1 by Lm2;
A10: r*((1/2)*q2`2)-r*((1/2)*q3`2)+r = r*((1/2)*(q2`2-q3`2)+1)
    .= 1 by A6,XCMPLX_1:106;
  ((1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)-|[1,0]|))`2 = ((1-r)*(q2+|[-1,1]|))
  `2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm1
    .= ((1-r)*q2+(1-r)*|[-1,1]|)`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by
RLVECT_1:def 5
    .= ((1-r)*q2)`2+((1-r)*|[-1,1]|)`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm1
    .= ((1-r)*q2)`2+(1-r)*|[-1,1]|`2+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm3
    .= ((1-r)*q2)`2+(1-r)*1+(r*(1/2*(q2+q3)-|[1,0]|))`2 by EUCLID:52
    .= (1-r)*q2`2+(1-r)*1+(r*(1/2*(q2+q3)-|[1,0]|))`2 by Lm3
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2+q3)-|[1,0]|)`2 by Lm3
    .= (1-r)*q2`2+(1-r)+r*((1/2*(q2+q3))`2-|[1,0]|`2) by Lm2
    .= (1-r)*q2`2+(1-r)+r*((1/2*(q2+q3))`2-0) by EUCLID:52
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2+q3)`2) by Lm3
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2`2+q3`2)) by Lm1
    .= q2`2-0 by A10
    .= q2`2-|[1,0]|`2 by EUCLID:52
    .= (q2-|[1,0]|)`2 by Lm2;
  then
  (1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)-|[1,0]|) = |[(q2-|[1,0]|)`1,(q2-|[1,
  0]|)`2]| by A9,EUCLID:53
    .= q2-|[1,0]| by EUCLID:53;
  then q2-|[1,0]| in LSeg(q2+|[-1,1]|,1/2*(q2+q3)-|[1,0]|) by A6,A7;
  then
A11: LSeg(q2+|[-1,1]|,1/2*(q2+q3)-|[1,0]|) = LSeg(q2+|[-1,1]|,q2-|[1,0]|) \/
  LSeg(q2-|[1,0]|,1/2*(q2+q3)-|[1,0]|) by TOPREAL1:5;
  set I1 = Int cell(G,0,width G), I2 = Int cell(G,0,width G -' 1);
A12: I1 \/ I2 \/ { q2-|[1,0]| } = I1 \/ (I2 \/ ({ q2-|[1,0]| } \/ { q2-|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2-|[1,0]| } \/ { q2-|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { q2-|[1,0]| } \/ (I2 \/ { q2-|[1,0]| }) by XBOOLE_1:4;
A13: LSeg(q2+|[-1,1]|,q2-|[1,0]|) c= I1 \/ { q2-|[1,0]| } by Th58;
  LSeg(q2-|[1,0]|,1/2*(q2+q3)-|[1,0]|) c= I2 \/ { q2-|[1,0]| } by A3,A4,A5,Th49
;
  hence thesis by A11,A13,A12,XBOOLE_1:13;
end;

theorem
  1 < len G & 1 < width G implies LSeg(G*(len G,width G)+|[1,1]|, 1/2*(G
*(len G,width G)+G*(len G,width G -' 1))+|[1,0]|) c= Int cell(G,len G,width G)
  \/ Int cell(G,len G,width G -' 1) \/ { G*(len G,width G)+|[1,0]| }
proof
  assume that
A1: 1 < len G and
A2: 1 < width G;
  set q2 = G*(len G,width G), q3 = G*(len G,width G -' 1), r = 1/(1/2*(q2`2-q3
  `2)+1);
A3: width G -' 1 + 1 = width G by A2,XREAL_1:235;
  then
A4: width G -' 1 >= 1 by A2,NAT_1:13;
A5: width G -' 1 < width G by A3,NAT_1:13;
  then q3`2 < q2`2 by A1,A4,GOBOARD5:4;
  then
A6: q2`2-q3`2 > 0 by XREAL_1:50;
  then 1 < 1/2*(q2`2-q3`2)+1 by XREAL_1:29,129;
  then
A7: r < 1 by XREAL_1:212;
A8: q2`1 = G*(len G,1)`1 by A1,A2,GOBOARD5:2
    .= q3`1 by A1,A4,A5,GOBOARD5:2;
A9: ((1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[1,0]|))`1 = ((1-r)*(q2+|[1,1]|))`1
  +(r*(1/2*(q2+q3)+|[1,0]|))`1 by Lm1
    .= (1-r)*(q2+|[1,1]|)`1+(r*(1/2*(q2+q3)+|[1,0]|))`1 by Lm3
    .= (1-r)*(q2+|[1,1]|)`1+r*(1/2*(q2+q3)+|[1,0]|)`1 by Lm3
    .= (1-r)*(q2`1+|[1,1]|`1)+r*(1/2*(q2+q3)+|[1,0]|)`1 by Lm1
    .= (1-r)*(q2`1+|[1,1]|`1)+r*((1/2*(q2+q3))`1+|[1,0]|`1) by Lm1
    .= (1-r)*(q2`1+1)+r*((1/2*(q2+q3))`1+|[1,0]|`1) by EUCLID:52
    .= (1-r)*q2`1+(1-r)*1+r*((1/2*(q2+q3))`1+1) by EUCLID:52
    .= (1-r)*q2`1+r*(1/2*(q2+q3))`1+((1-r)+r)
    .= (1-r)*q2`1+r*(1/2*(q2+q3)`1)+1 by Lm3
    .= (1-r)*q2`1+r*(1/2*(q2`1+q2`1))+1 by A8,Lm1
    .= q2`1+|[1,0]|`1 by EUCLID:52
    .= (q2+|[1,0]|)`1 by Lm1;
A10: r*((1/2)*q2`2)-r*((1/2)*q3`2)+r = r*((1/2)*(q2`2-q3`2)+1)
    .= 1 by A6,XCMPLX_1:106;
  ((1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[1,0]|))`2 = ((1-r)*(q2+|[1,1]|))`2
  +(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm1
    .= ((1-r)*q2+(1-r)*|[1,1]|)`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by RLVECT_1:def 5
    .= ((1-r)*q2)`2+((1-r)*|[1,1]|)`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm1
    .= ((1-r)*q2)`2+(1-r)*|[1,1]|`2+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm3
    .= ((1-r)*q2)`2+(1-r)*1+(r*(1/2*(q2+q3)+|[1,0]|))`2 by EUCLID:52
    .= (1-r)*q2`2+(1-r)+(r*(1/2*(q2+q3)+|[1,0]|))`2 by Lm3
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2+q3)+|[1,0]|)`2 by Lm3
    .= (1-r)*q2`2+(1-r)+r*((1/2*(q2+q3))`2+|[1,0]|`2) by Lm1
    .= (1-r)*q2`2+(1-r)+r*((1/2*(q2+q3))`2+0) by EUCLID:52
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2+q3)`2) by Lm3
    .= (1-r)*q2`2+(1-r)+r*(1/2*(q2`2+q3`2)) by Lm1
    .= q2`2+0 by A10
    .= q2`2+|[1,0]|`2 by EUCLID:52
    .= (q2+|[1,0]|)`2 by Lm1;
  then
  (1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[1,0]|) = |[(q2+|[1,0]|)`1,(q2+|[1,0
  ]|)`2]| by A9,EUCLID:53
    .= q2+|[1,0]| by EUCLID:53;
  then q2+|[1,0]| in LSeg(q2+|[1,1]|,1/2*(q2+q3)+|[1,0]|) by A6,A7;
  then
A11: LSeg(q2+|[1,1]|,1/2*(q2+q3)+|[1,0]|) = LSeg(q2+|[1,1]|,q2+|[1,0]|) \/
  LSeg(q2+|[1,0]|,1/2*(q2+q3)+|[1,0]|) by TOPREAL1:5;
  set I1 = Int cell(G,len G,width G), I2 = Int cell(G,len G,width G -' 1);
A12: I1 \/ I2 \/ { q2+|[1,0]| } = I1 \/ (I2 \/ ({ q2+|[1,0]| } \/ { q2+|[1,0
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2+|[1,0]| } \/ { q2+|[1,0]| }) by XBOOLE_1:4
    .= I1 \/ { q2+|[1,0]| } \/ (I2 \/ { q2+|[1,0]| }) by XBOOLE_1:4;
A13: LSeg(q2+|[1,1]|,q2+|[1,0]|) c= I1 \/ { q2+|[1,0]| } by Th59;
  LSeg(q2+|[1,0]|,1/2*(q2+q3)+|[1,0]|) c= I2 \/ { q2+|[1,0]| } by A3,A4,A5,Th51
;
  hence thesis by A11,A13,A12,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 < len G implies LSeg(G*(1,1)-|[1,1]|,1/2*(G*(1,1)+G*(2
  ,1))-|[0,1]|) c= Int cell(G,0,0) \/ Int cell(G,1,0) \/ { G*(1,1)-|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 < len G;
  set q2 = G*(1,1), q3 = G*(2,1), r = 1/(1/2*(q3`1-q2`1)+1);
A3: 0+(1+1) <= len G by A2,NAT_1:13;
  then
A4: q2`2 = q3`2 by A1,GOBOARD5:1;
  q2`1 < q3`1 by A1,A3,GOBOARD5:3;
  then
A5: q3`1-q2`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`1-q2`1)+1 by XREAL_1:29,129;
  then
A6: r < 1 by XREAL_1:212;
A7: ((1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[0,1]|))`2 = ((1-r)*(q2-|[1,1]|))`2
  +(r*(1/2*(q2+q3)-|[0,1]|))`2 by Lm1
    .= (1-r)*(q2-|[1,1]|)`2+(r*(1/2*(q2+q3)-|[0,1]|))`2 by Lm3
    .= (1-r)*(q2-|[1,1]|)`2+r*(1/2*(q2+q3)-|[0,1]|)`2 by Lm3
    .= (1-r)*(q2`2-|[1,1]|`2)+r*(1/2*(q2+q3)-|[0,1]|)`2 by Lm2
    .= (1-r)*(q2`2-|[1,1]|`2)+r*((1/2*(q2+q3))`2-|[0,1]|`2) by Lm2
    .= (1-r)*(q2`2-1)+r*((1/2*(q2+q3))`2-|[0,1]|`2) by EUCLID:52
    .= (1-r)*q2`2-(1-r)*1+r*((1/2*(q2+q3))`2-1) by EUCLID:52
    .= (1-r)*q2`2+r*(1/2*(q2+q3))`2-((1-r)+r)
    .= (1-r)*q2`2+r*(1/2*(q2+q3)`2)-1 by Lm3
    .= (1-r)*q2`2+r*(1/2*(q2`2+q2`2))-1 by A4,Lm1
    .= q2`2-|[0,1]|`2 by EUCLID:52
    .= (q2-|[0,1]|)`2 by Lm2;
A8: r*((1/2)*q3`1)-r*((1/2)*q2`1)+r = r*((1/2)*(q3`1-q2`1)+1)
    .= 1 by A5,XCMPLX_1:106;
  ((1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[0,1]|))`1 = ((1-r)*(q2-|[1,1]|))`1
  +(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm1
    .= ((1-r)*q2-(1-r)*|[1,1]|)`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by RLVECT_1:34
    .= ((1-r)*q2)`1-((1-r)*|[1,1]|)`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm2
    .= ((1-r)*q2)`1-(1-r)*|[1,1]|`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm3
    .= ((1-r)*q2)`1-(1-r)*1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by EUCLID:52
    .= (1-r)*q2`1-(1-r)*1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm3
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2+q3)-|[0,1]|)`1 by Lm3
    .= (1-r)*q2`1-(1-r)+r*((1/2*(q2+q3))`1-|[0,1]|`1) by Lm2
    .= (1-r)*q2`1-(1-r)+r*((1/2*(q2+q3))`1-0) by EUCLID:52
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2+q3)`1) by Lm3
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2`1+q3`1)) by Lm1
    .= q2`1-0 by A8
    .= q2`1-|[0,1]|`1 by EUCLID:52
    .= (q2-|[0,1]|)`1 by Lm2;
  then
  (1-r)*(q2-|[1,1]|)+r*(1/2*(q2+q3)-|[0,1]|) = |[(q2-|[0,1]|)`1,(q2-|[0,1
  ]|)`2]| by A7,EUCLID:53
    .= q2-|[0,1]| by EUCLID:53;
  then q2-|[0,1]| in LSeg(q2-|[1,1]|,1/2*(q2+q3)-|[0,1]|) by A5,A6;
  then
A9: LSeg(q2-|[1,1]|,1/2*(q2+q3)-|[0,1]|) = LSeg(q2-|[1,1]|,q2-|[0,1]|) \/
  LSeg(q2-|[0,1]|,1/2*(q2+q3)-|[0,1]|) by TOPREAL1:5;
  set I1 = Int cell(G,0,0), I2 = Int cell(G,1,0);
  0+1+1 = 0+(1+1);
  then
A10: LSeg(q2-|[0,1]|,1/2*(q2+q3)-|[0,1]|) c= I2 \/ { q2-|[0,1]| } by A2,Th52;
A11: I1 \/ I2 \/ { q2-|[0,1]| } = I1 \/ (I2 \/ ({ q2-|[0,1]| } \/ { q2-|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2-|[0,1]| } \/ { q2-|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { q2-|[0,1]| } \/ (I2 \/ { q2-|[0,1]| }) by XBOOLE_1:4;
  LSeg(q2-|[1,1]|,q2-|[0,1]|) c= I1 \/ { q2-|[0,1]| } by Th60;
  hence thesis by A9,A10,A11,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 < len G implies LSeg(G*(1,width G)+|[-1,1]|,1/2*(G*(1,
width G)+G*(2,width G))+|[0,1]|) c= Int cell(G,0,width G) \/ Int cell(G,1,width
  G) \/ { G*(1,width G)+|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 < len G;
  set q2 = G*(1,width G), q3 = G*(2,width G), r = 1/(1/2*(q3`1-q2`1)+1);
A3: 0+(1+1) <= len G by A2,NAT_1:13;
  then
A4: q2`2 = q3`2 by A1,GOBOARD5:1;
  q2`1 < q3`1 by A1,A3,GOBOARD5:3;
  then
A5: q3`1-q2`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(q3`1-q2`1)+1 by XREAL_1:29,129;
  then
A6: r < 1 by XREAL_1:212;
A7: ((1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)+|[0,1]|))`2 = ((1-r)*(q2+|[-1,1]|))
  `2+(r*(1/2*(q2+q3)+|[0,1]|))`2 by Lm1
    .= (1-r)*(q2+|[-1,1]|)`2+(r*(1/2*(q2+q3)+|[0,1]|))`2 by Lm3
    .= (1-r)*(q2+|[-1,1]|)`2+r*(1/2*(q2+q3)+|[0,1]|)`2 by Lm3
    .= (1-r)*(q2`2+|[-1,1]|`2)+r*(1/2*(q2+q3)+|[0,1]|)`2 by Lm1
    .= (1-r)*(q2`2+|[-1,1]|`2)+r*((1/2*(q2+q3))`2+|[0,1]|`2) by Lm1
    .= (1-r)*(q2`2+1)+r*((1/2*(q2+q3))`2+|[0,1]|`2) by EUCLID:52
    .= (1-r)*q2`2+(1-r)*1+r*((1/2*(q2+q3))`2+1) by EUCLID:52
    .= (1-r)*q2`2+r*(1/2*(q2+q3))`2+((1-r)+r)
    .= (1-r)*q2`2+r*(1/2*(q2+q3)`2)+1 by Lm3
    .= (1-r)*q2`2+r*(1/2*(q2`2+q2`2))+1 by A4,Lm1
    .= q2`2+|[0,1]|`2 by EUCLID:52
    .= (q2+|[0,1]|)`2 by Lm1;
A8: r*((1/2)*q3`1)-r*((1/2)*q2`1)+r = r*((1/2)*(q3`1-q2`1)+1)
    .= 1 by A5,XCMPLX_1:106;
  ((1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)+|[0,1]|))`1 = ((1-r)*(q2+|[-1,1]|))
  `1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm1
    .= ((1-r)*q2+(1-r)*|[-1,1]|)`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by
RLVECT_1:def 5
    .= ((1-r)*q2)`1+((1-r)*|[-1,1]|)`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm1
    .= ((1-r)*q2)`1+(1-r)*|[-1,1]|`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm3
    .= ((1-r)*q2)`1+(1-r)*(-1)+(r*(1/2*(q2+q3)+|[0,1]|))`1 by EUCLID:52
    .= ((1-r)*q2)`1-(1-r)+(r*(1/2*(q2+q3)+|[0,1]|))`1
    .= (1-r)*q2`1-(1-r)+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm3
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2+q3)+|[0,1]|)`1 by Lm3
    .= (1-r)*q2`1-(1-r)+r*((1/2*(q2+q3))`1+|[0,1]|`1) by Lm1
    .= (1-r)*q2`1-(1-r)+r*((1/2*(q2+q3))`1+0) by EUCLID:52
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2+q3)`1) by Lm3
    .= (1-r)*q2`1-(1-r)+r*(1/2*(q2`1+q3`1)) by Lm1
    .= q2`1+0 by A8
    .= q2`1+|[0,1]|`1 by EUCLID:52
    .= (q2+|[0,1]|)`1 by Lm1;
  then
  (1-r)*(q2+|[-1,1]|)+r*(1/2*(q2+q3)+|[0,1]|) = |[(q2+|[0,1]|)`1,(q2+|[0,
  1]|)`2]| by A7,EUCLID:53
    .= q2+|[0,1]| by EUCLID:53;
  then q2+|[0,1]| in LSeg(q2+|[-1,1]|,1/2*(q2+q3)+|[0,1]|) by A5,A6;
  then
A9: LSeg(q2+|[-1,1]|,1/2*(q2+q3)+|[0,1]|) = LSeg(q2+|[-1,1]|,q2+|[0,1]|) \/
  LSeg(q2+|[0,1]|,1/2*(q2+q3)+|[0,1]|) by TOPREAL1:5;
  set I1 = Int cell(G,0,width G), I2 = Int cell(G,1,width G);
  0+1+1 = 0+(1+1);
  then
A10: LSeg(q2+|[0,1]|,1/2*(q2+q3)+|[0,1]|) c= I2 \/ { q2+|[0,1]| } by A2,Th54;
A11: I1 \/ I2 \/ { q2+|[0,1]| } = I1 \/ (I2 \/ ({ q2+|[0,1]| } \/ { q2+|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2+|[0,1]| } \/ { q2+|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { q2+|[0,1]| } \/ (I2 \/ { q2+|[0,1]| }) by XBOOLE_1:4;
  LSeg(q2+|[-1,1]|,q2+|[0,1]|) c= I1 \/ { q2+|[0,1]| } by Th62;
  hence thesis by A9,A10,A11,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 < len G implies LSeg(G*(len G,1)+|[1,-1]|,1/2*(G*(len
G,1)+G*(len G -' 1,1))-|[0,1]|) c= Int cell(G,len G,0) \/ Int cell(G,len G -' 1
  ,0) \/ { G*(len G,1)-|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 < len G;
  set q2 = G*(len G,1), q3 = G*(len G -' 1,1), r = 1/(1/2*(q2`1-q3`1)+1);
A3: len G -' 1 + 1 = len G by A2,XREAL_1:235;
  then
A4: len G -' 1 >= 1 by A2,NAT_1:13;
A5: len G -'1 < len G by A3,NAT_1:13;
  then q3`1 < q2`1 by A1,A4,GOBOARD5:3;
  then
A6: q2`1-q3`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(q2`1-q3`1)+1 by XREAL_1:29,129;
  then
A7: r < 1 by XREAL_1:212;
A8: q2`2 = G*(1,1)`2 by A1,A2,GOBOARD5:1
    .= q3`2 by A1,A4,A5,GOBOARD5:1;
A9: ((1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)-|[0,1]|))`2 = ((1-r)*(q2+|[1,-1]|))
  `2+(r*(1/2*(q2+q3)-|[0,1]|))`2 by Lm1
    .= (1-r)*(q2+|[1,-1]|)`2+(r*(1/2*(q2+q3)-|[0,1]|))`2 by Lm3
    .= (1-r)*(q2+|[1,-1]|)`2+r*(1/2*(q2+q3)-|[0,1]|)`2 by Lm3
    .= (1-r)*(q2`2+|[1,-1]|`2)+r*(1/2*(q2+q3)-|[0,1]|)`2 by Lm1
    .= (1-r)*(q2`2+|[1,-1]|`2)+r*((1/2*(q2+q3))`2-|[0,1]|`2) by Lm2
    .= (1-r)*(q2`2+-1)+r*((1/2*(q2+q3))`2-|[0,1]|`2) by EUCLID:52
    .= (1-r)*(q2`2-1)+r*((1/2*(q2+q3))`2-1) by EUCLID:52
    .= (1-r)*q2`2+r*(1/2*(q2+q3))`2-1
    .= (1-r)*q2`2+r*(1/2*(q2+q3)`2)-1 by Lm3
    .= (1-r)*q2`2+r*(1/2*(q2`2+q2`2))-1 by A8,Lm1
    .= q2`2-|[0,1]|`2 by EUCLID:52
    .= (q2-|[0,1]|)`2 by Lm2;
A10: r*((1/2)*q2`1)-r*((1/2)*q3`1)+r = r*((1/2)*(q2`1-q3`1)+1)
    .= 1 by A6,XCMPLX_1:106;
  ((1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)-|[0,1]|))`1 = ((1-r)*(q2+|[1,-1]|))
  `1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm1
    .= ((1-r)*q2+(1-r)*|[1,-1]|)`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by
RLVECT_1:def 5
    .= ((1-r)*q2)`1+((1-r)*|[1,-1]|)`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm1
    .= ((1-r)*q2)`1+(1-r)*|[1,-1]|`1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm3
    .= ((1-r)*q2)`1+(1-r)*1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by EUCLID:52
    .= (1-r)*q2`1+(1-r)*1+(r*(1/2*(q2+q3)-|[0,1]|))`1 by Lm3
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2+q3)-|[0,1]|)`1 by Lm3
    .= (1-r)*q2`1+(1-r)+r*((1/2*(q2+q3))`1-|[0,1]|`1) by Lm2
    .= (1-r)*q2`1+(1-r)+r*((1/2*(q2+q3))`1-0) by EUCLID:52
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2+q3)`1) by Lm3
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2`1+q3`1)) by Lm1
    .= q2`1-0 by A10
    .= q2`1-|[0,1]|`1 by EUCLID:52
    .= (q2-|[0,1]|)`1 by Lm2;
  then
  (1-r)*(q2+|[1,-1]|)+r*(1/2*(q2+q3)-|[0,1]|) = |[(q2-|[0,1]|)`1,(q2-|[0,
  1]|)`2]| by A9,EUCLID:53
    .= q2-|[0,1]| by EUCLID:53;
  then q2-|[0,1]| in LSeg(q2+|[1,-1]|,1/2*(q2+q3)-|[0,1]|) by A6,A7;
  then
A11: LSeg(q2+|[1,-1]|,1/2*(q2+q3)-|[0,1]|) = LSeg(q2+|[1,-1]|,q2-|[0,1]|) \/
  LSeg(q2-|[0,1]|,1/2*(q2+q3)-|[0,1]|) by TOPREAL1:5;
  set I1 = Int cell(G,len G,0), I2 = Int cell(G,len G -' 1,0);
A12: I1 \/ I2 \/ { q2-|[0,1]| } = I1 \/ (I2 \/ ({ q2-|[0,1]| } \/ { q2-|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2-|[0,1]| } \/ { q2-|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { q2-|[0,1]| } \/ (I2 \/ { q2-|[0,1]| }) by XBOOLE_1:4;
A13: LSeg(q2+|[1,-1]|,q2-|[0,1]|) c= I1 \/ { q2-|[0,1]| } by Th61;
  LSeg(q2-|[0,1]|,1/2*(q2+q3)-|[0,1]|) c= I2 \/ { q2-|[0,1]| } by A3,A4,A5,Th53
;
  hence thesis by A11,A13,A12,XBOOLE_1:13;
end;

theorem
  1 < width G & 1 < len G implies LSeg(G*(len G,width G)+|[1,1]|, 1/2*(G
*(len G,width G)+G*(len G -' 1,width G))+|[0,1]|) c= Int cell(G,len G,width G)
  \/ Int cell(G,len G -' 1,width G) \/ { G*(len G,width G)+|[0,1]| }
proof
  assume that
A1: 1 < width G and
A2: 1 < len G;
  set q2 = G*(len G,width G), q3 = G*(len G -' 1,width G), r = 1/(1/2*(q2`1-q3
  `1)+1);
A3: len G -' 1 + 1 = len G by A2,XREAL_1:235;
  then
A4: len G -' 1 >= 1 by A2,NAT_1:13;
A5: len G -' 1 < len G by A3,NAT_1:13;
  then q3`1 < q2`1 by A1,A4,GOBOARD5:3;
  then
A6: q2`1-q3`1 > 0 by XREAL_1:50;
  then 1 < 1/2*(q2`1-q3`1)+1 by XREAL_1:29,129;
  then
A7: r < 1 by XREAL_1:212;
A8: q2`2 = G*(1,width G)`2 by A1,A2,GOBOARD5:1
    .= q3`2 by A1,A4,A5,GOBOARD5:1;
A9: ((1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[0,1]|))`2 = ((1-r)*(q2+|[1,1]|))`2
  +(r*(1/2*(q2+q3)+|[0,1]|))`2 by Lm1
    .= (1-r)*(q2+|[1,1]|)`2+(r*(1/2*(q2+q3)+|[0,1]|))`2 by Lm3
    .= (1-r)*(q2+|[1,1]|)`2+r*(1/2*(q2+q3)+|[0,1]|)`2 by Lm3
    .= (1-r)*(q2`2+|[1,1]|`2)+r*(1/2*(q2+q3)+|[0,1]|)`2 by Lm1
    .= (1-r)*(q2`2+|[1,1]|`2)+r*((1/2*(q2+q3))`2+|[0,1]|`2) by Lm1
    .= (1-r)*(q2`2+1)+r*((1/2*(q2+q3))`2+|[0,1]|`2) by EUCLID:52
    .= (1-r)*q2`2+(1-r)*1+r*((1/2*(q2+q3))`2+1) by EUCLID:52
    .= (1-r)*q2`2+r*(1/2*(q2+q3))`2+((1-r)+r)
    .= (1-r)*q2`2+r*(1/2*(q2+q3)`2)+1 by Lm3
    .= (1-r)*q2`2+r*(1/2*(q2`2+q2`2))+1 by A8,Lm1
    .= q2`2+|[0,1]|`2 by EUCLID:52
    .= (q2+|[0,1]|)`2 by Lm1;
A10: r*((1/2)*q2`1)-r*((1/2)*q3`1)+r = r*((1/2)*(q2`1-q3`1)+1)
    .= 1 by A6,XCMPLX_1:106;
  ((1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[0,1]|))`1 = ((1-r)*(q2+|[1,1]|))`1
  +(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm1
    .= ((1-r)*q2+(1-r)*|[1,1]|)`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by RLVECT_1:def 5
    .= ((1-r)*q2)`1+((1-r)*|[1,1]|)`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm1
    .= ((1-r)*q2)`1+(1-r)*|[1,1]|`1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm3
    .= ((1-r)*q2)`1+(1-r)*1+(r*(1/2*(q2+q3)+|[0,1]|))`1 by EUCLID:52
    .= (1-r)*q2`1+(1-r)+(r*(1/2*(q2+q3)+|[0,1]|))`1 by Lm3
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2+q3)+|[0,1]|)`1 by Lm3
    .= (1-r)*q2`1+(1-r)+r*((1/2*(q2+q3))`1+|[0,1]|`1) by Lm1
    .= (1-r)*q2`1+(1-r)+r*((1/2*(q2+q3))`1+0) by EUCLID:52
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2+q3)`1) by Lm3
    .= (1-r)*q2`1+(1-r)+r*(1/2*(q2`1+q3`1)) by Lm1
    .= q2`1+0 by A10
    .= q2`1+|[0,1]|`1 by EUCLID:52
    .= (q2+|[0,1]|)`1 by Lm1;
  then
  (1-r)*(q2+|[1,1]|)+r*(1/2*(q2+q3)+|[0,1]|) = |[(q2+|[0,1]|)`1,(q2+|[0,1
  ]|)`2]| by A9,EUCLID:53
    .= q2+|[0,1]| by EUCLID:53;
  then q2+|[0,1]| in LSeg(q2+|[1,1]|,1/2*(q2+q3)+|[0,1]|) by A6,A7;
  then
A11: LSeg(q2+|[1,1]|,1/2*(q2+q3)+|[0,1]|) = LSeg(q2+|[1,1]|,q2+|[0,1]|) \/
  LSeg(q2+|[0,1]|,1/2*(q2+q3)+|[0,1]|) by TOPREAL1:5;
  set I1 = Int cell(G,len G,width G), I2 = Int cell(G,len G -' 1,width G);
A12: I1 \/ I2 \/ { q2+|[0,1]| } = I1 \/ (I2 \/ ({ q2+|[0,1]| } \/ { q2+|[0,1
  ]| })) by XBOOLE_1:4
    .= I1 \/ (I2 \/ { q2+|[0,1]| } \/ { q2+|[0,1]| }) by XBOOLE_1:4
    .= I1 \/ { q2+|[0,1]| } \/ (I2 \/ { q2+|[0,1]| }) by XBOOLE_1:4;
A13: LSeg(q2+|[1,1]|,q2+|[0,1]|) c= I1 \/ { q2+|[0,1]| } by Th63;
  LSeg(q2+|[0,1]|,1/2*(q2+q3)+|[0,1]|) c= I2 \/ { q2+|[0,1]| } by A3,A4,A5,Th55
;
  hence thesis by A11,A13,A12,XBOOLE_1:13;
end;

theorem
  1 <= i & i+1 <= len G & 1 <= j & j+1 <= width G implies LSeg(1/2*(G*(i
  ,j)+G*(i+1,j+1)),p) meets Int cell(G,i,j)
proof
  assume
A1: 1 <= i & i+1 <= len G & 1 <= j & j+1 <= width G;
  now
    take a = 1/2*(G*(i,j)+G*(i+1,j+1));
    thus a in LSeg(1/2*(G*(i,j)+G*(i+1,j+1)),p) by RLTOPSP1:68;
    thus a in Int cell(G,i,j) by A1,Th31;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  1 <= i & i+1 <= len G implies LSeg(p,1/2*(G*(i,width G)+G*(i+1,width G
  ))+|[0,1]|) meets Int cell(G,i,width G)
proof
  assume
A1: 1 <= i & i+1 <= len G;
  now
    take a = 1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|;
    thus a in LSeg(p,1/2*(G*(i,width G)+G*(i+1,width G))+|[0,1]|) by
RLTOPSP1:68;
    thus a in Int cell(G,i,width G) by A1,Th32;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  1 <= i & i+1 <= len G implies LSeg(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|,p)
  meets Int cell(G,i,0)
proof
  assume
A1: 1 <= i & i+1 <= len G;
  now
    take a = 1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|;
    thus a in LSeg(1/2*(G*(i,1)+G*(i+1,1))-|[0,1]|,p) by RLTOPSP1:68;
    thus a in Int cell(G,i,0) by A1,Th33;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  1 <= j & j+1 <= width G implies LSeg(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|,p
  ) meets Int cell(G,0,j)
proof
  assume
A1: 1 <= j & j+1 <= width G;
  now
    take a = 1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|;
    thus a in LSeg(1/2*(G*(1,j)+G*(1,j+1))-|[1,0]|,p) by RLTOPSP1:68;
    thus a in Int cell(G,0,j) by A1,Th35;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  1 <= j & j+1 <= width G implies LSeg(p,1/2*(G*(len G,j)+G*(len G,j+1))
  +|[1,0]|) meets Int cell(G,len G,j)
proof
  assume
A1: 1 <= j & j+1 <= width G;
  now
    take a = 1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|;
    thus a in LSeg(p,1/2*(G*(len G,j)+G*(len G,j+1))+|[1,0]|) by RLTOPSP1:68;
    thus a in Int cell(G,len G,j) by A1,Th34;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  LSeg(p,G*(1,1)-|[1,1]|) meets Int cell(G,0,0)
proof
  now
    take a = G*(1,1)-|[1,1]|;
    thus a in LSeg(p,G*(1,1)-|[1,1]|) by RLTOPSP1:68;
    thus a in Int cell(G,0,0) by Th36;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  LSeg(p,G*(len G,width G)+|[1,1]|) meets Int cell(G,len G,width G)
proof
  now
    take a = G*(len G,width G)+|[1,1]|;
    thus a in LSeg(p,G*(len G,width G)+|[1,1]|) by RLTOPSP1:68;
    thus a in Int cell(G,len G,width G) by Th37;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  LSeg(p,G*(1,width G)+|[-1,1]|) meets Int cell(G,0,width G)
proof
  now
    take a = G*(1,width G)+|[-1,1]|;
    thus a in LSeg(p,G*(1,width G)+|[-1,1]|) by RLTOPSP1:68;
    thus a in Int cell(G,0,width G) by Th38;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem
  LSeg(p,G*(len G,1)+|[1,-1]|) meets Int cell(G,len G,0)
proof
  now
    take a = G*(len G,1)+|[1,-1]|;
    thus a in LSeg(p,G*(len G,1)+|[1,-1]|) by RLTOPSP1:68;
    thus a in Int cell(G,len G,0) by Th39;
  end;
  hence thesis by XBOOLE_0:3;
end;

theorem Th91:
  for M being non empty MetrSpace, p being Point of M, q being
Point of TopSpaceMetr M, r being Real st p = q & r > 0 holds Ball (p, r)
  is a_neighborhood of q
proof
  let M be non empty MetrSpace, p be Point of M, q be Point of TopSpaceMetr M,
  r be Real;
  reconsider A = Ball (p, r) as Subset of TopSpaceMetr M by TOPMETR:12;
  assume p = q & r > 0;
  then q in A by Th1;
  hence thesis by CONNSP_2:3,TOPMETR:14;
end;

theorem
  for M being non empty MetrSpace, A being Subset of TopSpaceMetr M, p
  being Point of M holds p in Cl A iff for r being Real st r > 0 holds
  Ball (p, r) meets A
proof
  let M be non empty MetrSpace, A be Subset of TopSpaceMetr M, p be Point of M;
  reconsider p9 = p as Point of TopSpaceMetr M by TOPMETR:12;
  hereby
    assume
A1: p in Cl A;
    let r be Real;
    reconsider B = Ball (p, r) as Subset of TopSpaceMetr M by TOPMETR:12;
    assume r > 0;
    then B is a_neighborhood of p9 by Th91;
    hence Ball (p, r) meets A by A1,CONNSP_2:27;
  end;
  assume
A2: for r being Real st r > 0 holds Ball (p, r) meets A;
  for G being a_neighborhood of p9 holds G meets A
  proof
    let G be a_neighborhood of p9;
    p in Int G by CONNSP_2:def 1;
    then ex r being Real st r > 0 & Ball (p, r) c= G by Th4;
    hence thesis by A2,XBOOLE_1:63;
  end;
  hence thesis by CONNSP_2:27;
end;

:: Moved from JORDAN19, AG 20.01.2006

theorem
  for A be Subset of TOP-REAL n for p be Point of TOP-REAL n for p9 be
  Point of Euclid n st p = p9 for s be Real st s > 0 holds p in Cl A iff
  for r be Real st 0 < r & r < s holds Ball (p9,r) meets A
proof
  let A be Subset of TOP-REAL n;
  let p be Point of TOP-REAL n;
  let p9 be Point of Euclid n;
  assume
A1: p = p9;
  let s be Real;
  assume
A2: s > 0;
  hereby
    assume
A3: p in Cl A;
    let r be Real;
    assume that
A4: 0 < r and
    r < s;
    reconsider B = Ball (p9,r) as Subset of TOP-REAL n by TOPREAL3:8;
    B is a_neighborhood of p by A1,A4,Th2;
    hence Ball (p9, r) meets A by A3,CONNSP_2:27;
  end;
  assume
A5: for r be Real st 0 < r & r < s holds Ball (p9,r) meets A;
  for G be a_neighborhood of p holds G meets A
  proof
    let G be a_neighborhood of p;
    p in Int G by CONNSP_2:def 1;
    then consider r9 be Real such that
A6: r9 > 0 and
A7: Ball (p9,r9) c= G by A1,Th5;
    set r = min(r9,s/2);
    Ball (p9,r) c= Ball (p9,r9) by PCOMPS_1:1,XXREAL_0:17;
    then
A8: Ball (p9,r) c= G by A7;
    s/2 < s & r <= s/2 by A2,XREAL_1:216,XXREAL_0:17;
    then
A9: r < s by XXREAL_0:2;
    s/2 > 0 by A2,XREAL_1:215;
    then r > 0 by A6,XXREAL_0:15;
    hence thesis by A5,A8,A9,XBOOLE_1:63;
  end;
  hence thesis by CONNSP_2:27;
end;