CARDFIL3

index · ← DBLSEQ_3 · FINTOPO7 →
:: Summable Family in a Commutative Group
::  by Roland Coghetto
::
:: Received August 14, 2015
:: Copyright (c) 2015-2026 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 POLYNOM1, PBOOLE, NAT_1, NUMBERS, FRECHET, PCOMPS_1, REAL_1,
      CARDFIL2, YELLOW13, CARD_1, XBOOLE_0, SUBSET_1, TARSKI, ORDINAL1,
      FUNCT_1, PRE_TOPC, STRUCT_0, XXREAL_0, RCOMP_1, METRIC_1, ARYTM_3,
      YELLOW19, NORMSP_1, NORMSP_2, ARYTM_1, SETFAM_1, ALGSTR_0, ZFMISC_1,
      SUPINF_2, CONNSP_2, TOPS_1, RELAT_2, RLTOPSP1, FILTER_0, XXREAL_1,
      ORDERS_2, WAYBEL_0, BINOP_1, RELAT_1, CARD_3, FUNCT_2, FINSUB_1,
      FINSEQ_1, FINSOP_1, SETWISEO, ORDINAL4, VECTSP_1, SERIES_1, YELLOW_1,
      TOPGRP_1, GROUP_1, SERIES_3, CARDFIL3, RLVECT_1, GROUP_1A;
 notations CARDFIL2, GROUP_1A, TARSKI, XBOOLE_0, SUBSET_1, FUNCT_1,
      ORDINAL1, FUNCT_2,
      TOPS_1, CONNSP_2, YELLOW13, RUSUB_4, RLTOPSP1, ORDERS_2, WAYBEL_0,
      METRIC_1, NUMBERS, XCMPLX_0, XREAL_0, NAT_1, XXREAL_0, STRUCT_0,
      ALGSTR_0, PRE_TOPC, NORMSP_0, NORMSP_1, NORMSP_2, FRECHET, YELLOW19,
      PCOMPS_1, ZFMISC_1, BINOP_1, PBOOLE, RELAT_1, FINSUB_1, RLVECT_1,
      FINSEQ_1, FINSOP_1, SETWISEO, VECTSP_1, YELLOW_1, TOPGRP_1, GROUP_1;
 constructors YELLOW_8, FRECHET, YELLOW19, TOPS_2, NAT_LAT, NORMSP_2, TOPS_1,
      RUSUB_4, YELLOW13, FINSOP_1, SETWISEO, FINSEQOP, MEMBERED, NAT_1,
      BORSUK_1, CARDFIL2, GROUP_1A;
 registrations GROUP_1A, PCOMPS_1, FRECHET, YELLOW19, XXREAL_0, XREAL_0, NAT_1,
      SUBSET_1, STRUCT_0, XCMPLX_0, CARD_1, METRIC_1, TOPS_1, RLVECT_1,
      RLTOPSP1, RELAT_1, XBOOLE_0, FUNCT_1, FINSEQ_1, PBOOLE, FINSUB_1,
      FVSUM_1, OSALG_1, YELLOW_1, TOPGRP_1, GROUP_1, MEMBERED, ORDERS_2;
 requirements REAL, NUMERALS, SUBSET, BOOLE;
 definitions YELLOW13;
 equalities ORDINAL1, ALGSTR_0;
 expansions TARSKI, FRECHET, XBOOLE_0, FUNCT_1, RELAT_1, CARDFIL2;
 theorems GROUP_1A, FRECHET, CONNSP_2, YELLOW_8, YELLOW19, TOPMETR, METRIC_1,
      NORMSP_2, PCOMPS_1, RLTOPSP1, YELLOW13, XBOOLE_0, RUSUB_4, CARD_FIL,
      RLVECT_1, TOPS_1, TOPGRP_1, FINSUB_1, FINSEQ_1, FINSOP_1, FINSEQ_4,
      BHSP_5, FVSUM_1, RELAT_1, TARSKI, XBOOLE_1, FUNCT_1, FINSEQ_2, FINSEQ_3,
      FUNCT_2, PARTFUN1, STRUCT_0, WAYBEL_0, YELLOW_1, GROUP_1, CARDFIL2;
 schemes FUNCT_2, BINOP_2;

begin :: Preliminaries

theorem
  for I being set holds {} is Element of Fin I
  proof
    let I be set;
A1: Fin {} c= Fin I by XBOOLE_1:2,FINSUB_1:10;
    {} in {{}} by TARSKI:def 1;
    hence thesis by A1,FINSUB_1:15;
  end;

theorem Th1:
  for I,J being set st J in Fin I holds
  ex p being FinSequence of I st J = rng p & p is one-to-one
  proof
    let I, J be set such that
A1: J in Fin I;
    consider p be FinSequence such that
A2: J = rng p & p is one-to-one by A1,FINSEQ_4:58;
    rng p c= I by A1,A2,FINSUB_1:def 5;
    then reconsider p as FinSequence of I by FINSEQ_1:def 4;
    take p;
    thus thesis by A2;
end;

theorem Th2:
  for I being set,
      Y being non empty set,
      x being Y-valued ManySortedSet of I,
      p being FinSequence of I holds
  p*x is FinSequence of Y
  proof
    let I be set, Y be non empty set,
    x be Y-valued ManySortedSet of I,
    p be FinSequence of I;
A1: dom x =I by PARTFUN1:def 2;
A2: rng x c= Y by RELAT_1:def 19;
    then
A3: x is Function of I,Y by A1,FUNCT_2:2;
    reconsider x1=x as Function of I,Y by A1,A2,FUNCT_2:2;
    reconsider xp=p*x1 as FinSequence;
    thus thesis by A3,FINSEQ_2:32;
  end;

theorem Th3:
  for I,X being non empty set,
      x being X-valued ManySortedSet of I,
      p,q being FinSequence of I holds
  (p^q) * x = (p * x) ^ (q  * x)
  proof
    let I,X be non empty set,
    x be X-valued ManySortedSet of I,
    p,q be FinSequence of I;
A1: dom x =I by PARTFUN1:def 2;
    rng x c= X by RELAT_1:def 19; then
A2: x is Function of I,X by A1,FUNCT_2:2; then
A3: dom (p * x)=dom p & dom (q*x)=dom q &
    dom ((p^q)*x)=dom (p^q) by FINSEQ_3:120;
A4: dom (p^q)=Seg (len p + len q) by FINSEQ_1:def 7;
A5: Seg len(p*x)=dom p & Seg len(q*x)=dom q by A3,FINSEQ_1:def 3;
A6: len (p*x)=len p & len (q*x)=len q by A5,FINSEQ_1:def 3; then
A7: dom ((p*x) ^ (q*x))= Seg(len p+len q) by FINSEQ_1:def 7;
    for t be object st t in dom ((p^q)*x) holds
    ((p^q) * x).t = ((p * x) ^ (q  * x)).t
    proof
      let t be object;
      assume
A8:   t in dom((p^q)*x);
A9:   t in dom(p^q) by A2,FINSEQ_3:120,A8;
A10:  ((p^q) * x).t=x.((p^q).t) by A2,FINSEQ_3:120,A8;
      now
        hereby
          assume
A11:      t in dom p;
          then
A12:      x.((p^q).t) =x.(p.t) &
          x.(p.t) = (p*x).t by FINSEQ_1:def 7,FUNCT_1:13;
          t in dom (p *x ) by A11,A2,FINSEQ_3:120;
          hence ((p^q) * x).t=((p * x) ^ (q  * x)).t
          by A12,A10,FINSEQ_1:def 7;
        end;
        assume ex n be Nat st n in dom q & t=len p + n;
        then consider n be Nat such that
A13:    n in dom q and
A14:    t=len p + n;
A15:    x.((p^q).(len p + n))=x.(q.n) by A13,FINSEQ_1:def 7;
        n in dom (q*x) by A13,A2,FINSEQ_3:120;
        then ((p * x) ^ (q  * x)).(len p + n)=(q * x).n by A6,FINSEQ_1:def 7;
        hence ((p^q) * x).t=((p * x) ^ (q  * x)).t
        by A13,A14,A15,A10,FUNCT_1:13;
      end;
      hence thesis by A9,FINSEQ_1:25;
    end;
    hence thesis by A7,A2,FINSEQ_3:120,A4;
  end;

definition
  let I being set,
      Y being non empty set,
      x being Y-valued ManySortedSet of I,
      p being FinSequence of I;
  func #(p,x) -> FinSequence of Y equals p*x;
  coherence by Th2;
end;

definition
  let I being set;
  func OrderedFIN I -> non empty transitive reflexive RelStr equals
  InclPoset Fin I;
  coherence;
end;

theorem Th4:
  for I being set holds [#]OrderedFIN I is directed
  proof
    let I be set;
A1: the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then
A2: [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    now
      let a,b be Element of OrderedFIN I;
      assume that
      a in [#]OrderedFIN I and
      b in [#]OrderedFIN I;
      reconsider z=a\/b as Element of OrderedFIN I by A1,FINSUB_1:def 1;
      take z;
      thus z in [#]OrderedFIN I &
      a <= z & b <= z by A1,A2,YELLOW_1:3,XBOOLE_1:7;
    end;
    hence thesis by WAYBEL_0:def 1;
  end;

begin :: Convergence in TopSpaceMetr

theorem Th5:
  for M being non empty MetrSpace,
      x being Point of TopSpaceMetr(M)
  holds Balls(x) is basis of BOOL2F NeighborhoodSystem x
  proof
    let M be non empty MetrSpace,x be Point of TopSpaceMetr(M);
    set F=BOOL2F NeighborhoodSystem x;
    now
      let t be object;
      assume
A1:   t in Balls(x);
      then reconsider t1=t as Subset of TopSpaceMetr(M);
      consider y being Point of M such that
A2:   y=x and
A3:   Balls(x)= { Ball(y,1/n) where n is Nat: n <> 0 } by FRECHET:def 1;
      consider n0 be Nat such that
A4:   t=Ball(y,1/n0) and
A5:   n0 <> 0 by A1,A3;
      reconsider r0=1/n0 as Real;
A6:   0 <r0 by A5;
      dist(y,y)<r0 by A6,METRIC_1:1; then
A7:   y in {q where q is Element of M:dist (y,q) < r0};
      t1 is open & x in t1 by A7,A4,TOPMETR:14,A2,METRIC_1:def 14;
      then t1 is a_neighborhood of x by CONNSP_2:3;
      then t in NeighborhoodSystem x by YELLOW19:2;
      hence t in F by CARDFIL2:def 20;
    end;
    then Balls(x) c= F;
    then reconsider BAX = Balls(x) as non empty Subset of F;
    now
      let f be Element of F;
      f in BOOL2F NeighborhoodSystem x;
      then f in NeighborhoodSystem x by CARDFIL2:def 20;
      then f is a_neighborhood of x by YELLOW19:2;
      then consider V being Subset of TopSpaceMetr(M) such that
A8:   V is open & V c= f & x in V by CONNSP_2:6;
      consider b being Subset of TopSpaceMetr(M) such that
A9:   b in Balls(x) & b c= V by A8,YELLOW_8:def 1;
      reconsider b as Element of BAX by A9;
      take b;
      thus b c= f by A8,A9;
    end;
    then BAX is filter_basis;
    hence thesis;
  end;

theorem
  for M being non empty MetrSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of TopSpaceMetr(M),
      x being Point of TopSpaceMetr(M),
      B being basis of BOOL2F NeighborhoodSystem x st
    [#]L is directed holds
      x in lim_f f
     iff
      for b being Element of B ex i being Element of L st
      for j being Element of L st i <=j holds f.j in b by CARDFIL2:84;

theorem
  for M being non empty MetrSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of TopSpaceMetr(M),
      x being Point of TopSpaceMetr(M) st
    [#]L is directed holds
      x in lim_f f
     iff
      for b being Element of Balls(x) ex n being Element of L st
      for m being Element of L st n <= m holds f.m in b
  proof
    let M be non empty MetrSpace,
    L be non empty transitive reflexive RelStr,
    f be Function of [#]L,the carrier of TopSpaceMetr(M),
    x be Point of TopSpaceMetr(M);
    assume
A1: [#]L is directed;
    Balls(x) is basis of BOOL2F NeighborhoodSystem x by Th5;
    hence thesis by A1,CARDFIL2:84;
  end;

theorem Th6:
  for M being non empty MetrSpace,
      s being sequence of the carrier of TopSpaceMetr(M),
      x being Point of TopSpaceMetr(M) holds
    x in lim_f s
      iff
    for b being Element of Balls(x) ex i being Nat st
    for j being Nat st i <=j holds s.j in b
  proof
    let M be non empty MetrSpace,
    s be sequence of the carrier of TopSpaceMetr(M),
    x be Point of TopSpaceMetr(M);
    Balls(x) is basis of BOOL2F NeighborhoodSystem x by Th5;
    hence thesis by CARDFIL2:97;
  end;

theorem Th7:
  for T being non empty TopStruct,
      s being sequence of T,
      x being Point of T holds
    x in Lim s
      iff
    for U1 being Subset of T st U1 is open & x in U1
    ex n being Nat st for m being Nat st n <= m holds s.m in U1
  proof
    let T be non empty TopStruct,s be sequence of T,
    x be Point of T;
    x in Lim s iff s is_convergent_to x by FRECHET:def 5;
    hence thesis;
  end;

theorem Th8:
  for M being non empty MetrSpace,
      s being sequence of the carrier of TopSpaceMetr(M),
      x being Point of TopSpaceMetr(M) holds
    x in Lim s
      iff
    for b being Element of Balls(x) ex n being Nat st
    for m being Nat st n <= m holds s.m in b
  proof
    let M be non empty MetrSpace,
    s be sequence of the carrier of TopSpaceMetr(M),
    x be Point of TopSpaceMetr(M);
    now
      hereby
        assume
A1:     x in Lim s;
        now
          let b be Element of Balls(x);
          Balls(x) is basis of BOOL2F NeighborhoodSystem x by Th5;
          then Balls(x) c= BOOL2F NeighborhoodSystem x;
          then b in BOOL2F NeighborhoodSystem x;
          then b in NeighborhoodSystem x by CARDFIL2:def 20;
          then b is a_neighborhood of x by YELLOW19:2;
          then consider V being Subset of TopSpaceMetr(M) such that
A2:       V is open and
A3:       V c= b and
A4:       x in V by CONNSP_2:6;
          consider n0 being Nat such that
A5:       for m being Nat st n0 <= m holds s.m in V by A2,A4,A1,Th7;
          take n0;
          thus for m being Nat st n0 <= m holds s.m in b by A3,A5;
        end;
        hence x in Lim s implies
        for b be Element of Balls(x)
        ex n being Nat st
        for m being Nat st n <= m holds s.m in b;
      end;
      assume
A6:   for b be Element of Balls(x)
      ex n being Nat st for m being Nat st n <= m holds s.m in b;
      now
        let U1 be Subset of TopSpaceMetr(M);
        assume U1 is open & x in U1;
        then U1 is a_neighborhood of x by CONNSP_2:6;
        then U1 in NeighborhoodSystem x by YELLOW19:2;
        then
A7:     U1 is Element of BOOL2F NeighborhoodSystem x by CARDFIL2:def 20;
        reconsider BAX=Balls(x) as
        non empty Subset of BOOL2F NeighborhoodSystem x by Th5;
        BAX is filter_basis by Th5;
        then consider b be Element of Balls(x) such that
A8:     b c= U1 by A7;
        consider n0 being Nat such that
A9:     for m being Nat st n0 <= m holds s.m in b by A6;
        take n0;
        thus for m being Nat st n0 <= m holds s.m in U1 by A9,A8;
      end;
      hence x in Lim s by Th7;
    end;
    hence thesis;
  end;

theorem
  for M being non empty MetrSpace,
      s being sequence of the carrier of TopSpaceMetr(M),
      x being Point of TopSpaceMetr(M) holds
    x in lim_f s
      iff
    x in Lim s
  proof
    let M be non empty MetrSpace,
    s be sequence of the carrier of TopSpaceMetr(M),
    x be Point of TopSpaceMetr(M);
    hereby
      assume x in lim_f s;
      then for b be Element of Balls(x) ex i be Nat st
      for j be Nat st i <=j holds s.j in b by Th6;
      hence x in Lim s by Th8;
    end;
    assume x in Lim s;
    then for b be Element of Balls(x) ex i be Nat st
    for j be Nat st i <=j holds s.j in b by Th8;
    hence x in lim_f s by Th6;
  end;

begin :: Convergence in RealNormSpace

theorem
  for N being RealNormSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of TopSpaceMetr MetricSpaceNorm(N),
      x being Point of TopSpaceMetr MetricSpaceNorm(N),
      B being basis of BOOL2F NeighborhoodSystem x st
  [#]L is directed holds
    x in lim_f f
     iff
    for b being Element of B ex i be Element of L st
    for j being Element of L st i <=j holds f.j in b by CARDFIL2:84;

theorem
  for N being RealNormSpace,
      x being Point of TopSpaceMetr MetricSpaceNorm N
  holds Balls(x) is basis of BOOL2F NeighborhoodSystem x by Th5;

theorem
  for N being RealNormSpace,
      s being sequence of the carrier of TopSpaceMetr MetricSpaceNorm(N),
      x being Point of TopSpaceMetr MetricSpaceNorm N holds
    x in lim_f s
      iff
    for b being Element of Balls(x) ex i being Nat st
    for j being Nat st i <=j holds s.j in b by Th6;

theorem
  for N being RealNormSpace,
      x being Point of TopSpaceMetr MetricSpaceNorm N holds
  ex y being Point of MetricSpaceNorm N st y = x &
  Balls x= {Ball(y,1/n) where n is Nat:n <> 0} by FRECHET:def 1;

theorem
  for N being RealNormSpace,
      x being Point of TopSpaceMetr MetricSpaceNorm N,
      y being Point of MetricSpaceNorm N,
      n being positive Nat st x=y holds
  Ball(y,1/n) in Balls x
  proof
    let N be RealNormSpace, x be Point of TopSpaceMetr MetricSpaceNorm N,
    y be Point of MetricSpaceNorm N,
    n be positive Nat such that
A1: x=y;
    set M=MetricSpaceNorm N;
    consider y1 be Point of M such that
A2: y1=x and
A3: Balls x = {Ball(y1,1/n) where n is Nat:n <> 0} by FRECHET:def 1;
    thus thesis by A1,A2,A3;
  end;

theorem
  for N being RealNormSpace,
      x being Point of MetricSpaceNorm N,
      n being Nat st n <> 0 holds
  Ball (x,1/n) = {q where q is Element of MetricSpaceNorm N : dist(x,q) < 1/n}
  by METRIC_1:def 14;

theorem
  for N being RealNormSpace,
      x being Element of MetricSpaceNorm N,
      n being Nat st n <> 0 holds
  ex y being Point of N st x=y &
  Ball (x,1/n) = {q where q is Point of N : ||.y-q.|| < 1/n} by NORMSP_2:2;

theorem
  for PM being MetrStruct holds
  TopSpaceMetr PM = TopStruct (#the carrier of PM, Family_open_set(PM)#)
  by PCOMPS_1:def 5;

theorem
  for PM being MetrStruct holds
  the carrier of TopStruct (#the carrier of PM, Family_open_set(PM)#) =
    the carrier of PM;

theorem
  for PM being MetrStruct holds
    the carrier of TopSpaceMetr PM =
    the carrier of TopStruct (#the carrier of PM, Family_open_set(PM)#)
      by PCOMPS_1:def 5;

theorem Th9:
  for PM being MetrStruct holds
  the carrier of TopSpaceMetr PM = the carrier of PM
  proof
    let PM be MetrStruct;
    the carrier of TopSpaceMetr PM=
    the carrier of TopStruct (#the carrier of PM,
    Family_open_set(PM)#) by PCOMPS_1:def 5;
    hence thesis;
  end;

theorem
  for N being RealNormSpace,
      s being sequence of the carrier of TopSpaceMetr MetricSpaceNorm N,
      j being Nat holds
  s.j is Element of the carrier of TopSpaceMetr MetricSpaceNorm N;

definition
  let N being RealNormSpace, x be Point of TopSpaceMetr MetricSpaceNorm N;
  func #x -> Point of N equals x;
  coherence
  proof
    MetricSpaceNorm N = MetrStruct(# the carrier of N,distance_by_norm_of N #)
    by NORMSP_2:def 2;
    hence x is Element of N by Th9;
  end;
end;

theorem
  for N being RealNormSpace,
      s being sequence of the carrier of TopSpaceMetr MetricSpaceNorm N,
      x being Point of TopSpaceMetr MetricSpaceNorm N holds
    x in lim_f s
      iff
    (for n being positive Nat ex i be Nat st for j being Nat st i <= j holds
     ||.#x- #(s.j) .|| < 1/n)
  proof
    let N be RealNormSpace,
    s be sequence of the carrier of TopSpaceMetr MetricSpaceNorm(N),
    x be Point of TopSpaceMetr MetricSpaceNorm N;
    reconsider x1=x as Point of TopSpaceMetr MetricSpaceNorm N;
    consider y0 be Point of MetricSpaceNorm N such that
A1: y0=x1 and
A2: Balls x1={Ball(y0,1/n) where n is Nat:n <> 0} by FRECHET:def 1;
A3: x in lim_f s implies
    (for n be positive Nat ex i be Nat st
    for j be Nat st i <= j holds ||.#x- #(s.j) .|| < 1/n)
    proof
      assume
A4:   x in lim_f s;
      now
        let n be positive Nat;
        Ball(y0,1/n) in Balls x1 by A2;
        then consider i0 be Nat such that
A5:     for j be Nat st i0 <= j holds s.j in Ball(y0,1/n) by A4,Th6;
A6:     now
          let j be Nat;
          assume
A7:       i0 <= j;
          consider y1 be Point of N such that
A8:       y0=y1 and
A9:       Ball (y0,1/n)={q where q is Point of N : ||.y1 - q.|| < 1/n}
          by NORMSP_2:2;
          s.j in {q where q is Point of N : ||.y1 - q.|| < 1/n} by A7,A5,A9;
          then consider q0 be Point of N such that
A10:       s.j=q0 and
A11:       ||.y1  - q0.|| < 1/n;
          thus ||.#x - #(s.j).|| < 1/n by A1,A8,A10,A11;
        end;
        take i0;
        thus for j be Nat st i0<=j holds ||.#x - #(s.j).|| < 1/n by A6;
      end;
      hence thesis;
    end;
    (for n be positive Nat ex i be Nat st for j be Nat st i<=j holds
    ||.#x - #(s.j).|| < 1/n) implies x in lim_f s
    proof
      assume
A12:  for n be positive Nat ex i be Nat st
      for j be Nat st i<=j holds
      ||.#x - #(s.j).|| < 1/n;
      for b be Element of Balls(x) ex i be Nat st
      for j be Nat st i <=j holds s.j in b
      proof
        let b be Element of Balls(x);
        b in {Ball(y0,1/n) where n is Nat:n <> 0} by A2;
        then consider n0 be Nat such that
A13:     b=Ball(y0,1/n0) and
A14:     n0 <> 0;
        consider i0 be Nat such that
A15:     for j be Nat st i0<=j holds ||.#x - #(s.j).|| < 1/n0 by A12,A14;
        take i0;
        for j be Nat st i0 <= j holds s.j in b
        proof
          let j be Nat;
          assume i0<=j; then
A16:      ||.#x1 - #(s.j).||< 1/n0 by A15;
          consider y1 be Point of N such that
A17:      y0=y1 and
A18:      Ball (y0,1/n0)={q where q is Point of N : ||.y1 - q.|| < 1/n0}
          by NORMSP_2:2;
          thus s.j in b by A1,A13,A16,A17,A18;
        end;
        hence thesis;
      end;
      hence thesis by Th6;
    end;
    hence thesis by A3;
  end;

begin :: Convergence in LinearTopSpace

theorem
  for X being non empty LinearTopSpace holds
  NeighborhoodSystem 0.X is local_base of X
  proof
    let X be non empty LinearTopSpace;
    reconsider p=0.X as Point of X;
    BOOL2F NeighborhoodSystem 0.X is Subset-Family of X;
    then reconsider NS0 =  (NeighborhoodSystem 0.X) as Subset-Family of X
    by CARDFIL2:def 20;
    for A being a_neighborhood of p ex P being a_neighborhood of p st
    ( P in NeighborhoodSystem p & P c= A ) by YELLOW19:2;
    then NS0 is basis of p by YELLOW13:def 2;
    hence thesis;
  end;

Lm1:
  for X being non empty addLoopStr,
      M being Subset of X holds
  for x,y being Point of X st y in M holds x+y in x+M
  proof
    let X be non empty addLoopStr, M be Subset of X;
    let x,y be Point of X;
    x + M = {x + u where u is Point of X: u in M} by RUSUB_4:def 8;
    hence thesis;
  end;

Lm2:
  for X being non empty LinearTopSpace,
      x being Point of X,
      O being local_base of X holds
  {x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X} is
  non empty Subset-Family of X
  proof
    let X be non empty LinearTopSpace,
    x be Point of X, O be local_base of X;
    set B={x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X};
    now let t be object;
      assume t in B;
      then consider U1 be Subset of X such that
A1:   t=x+U1 and
      U1 in O and
      U1 is a_neighborhood of 0.X;
      thus t in bool the carrier of X by A1;
    end;
    then B c= bool the carrier of X;
    then reconsider B1=B as Subset-Family of X;
A2: [#]X is a_neighborhood of 0.X by TOPGRP_1:21;
    consider V being a_neighborhood of 0.X such that
A3: V in O and
    V c= [#]X by A2, YELLOW13:def 2;
    x+V in B1 by A3;
    hence thesis;
  end;

theorem
  for X being LinearTopSpace,
      O being local_base of X,
      a being Point of X,
      P being Subset-Family of X st P = {a+U where U is Subset of X: U in O}
  holds P is basis of a
  proof
    let X be LinearTopSpace, O be basis of 0.X,
    a be Point of X,
    P be Subset-Family of X such that
A1: P = {a+U where U is Subset of X: U in O};
    let A be a_neighborhood of a;
    a in Int(A) by CONNSP_2:def 1;
    then (-a) + Int(A) is a_neighborhood of 0.X by RLTOPSP1:9,CONNSP_2:3;
    then consider V being a_neighborhood of 0.X such that
A2: V in O and
A3: V c= -a+Int(A) by YELLOW13:def 2;
    take U = a+V;
A4: a+0.X in a+Int(V) by Lm1,CONNSP_2:def 1;
    a+Int(V) c= Int(U) by RLTOPSP1:37;
    hence U is a_neighborhood of a by A4,CONNSP_2:def 1;
    thus U in P by A1,A2;
    U c= a+(-a+Int(A)) by A3,RLTOPSP1:8;
    then U c= a+(-a)+Int(A) by RLTOPSP1:6;
    then U c= 0.X+Int(A) by RLVECT_1:5;
    then Int(A) c= A & U c= Int(A) by RLTOPSP1:5,TOPS_1:16;
    hence thesis;
  end;

theorem
  for X being non empty LinearTopSpace,
      x being Point of X,
      O being local_base of X holds
  {x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X} =
  {x+U where U is Subset of X:U in O & U in NeighborhoodSystem 0.X}
  proof
    let X be non empty LinearTopSpace,
    x be Point of X, O be local_base of X;
    now
      let t be object;
      assume t in {x+U where U is Subset of X:U in O &
      U is a_neighborhood of 0.X};
      then consider U1 be Subset of X such that
A1:   t=x+U1 and
A2:   U1 in O and
A3:   U1 is a_neighborhood of 0.X;
      U1 in NeighborhoodSystem 0.X by A3,YELLOW19:2;
      hence t in {x+U where U is Subset of X:U in O &
      U in NeighborhoodSystem 0.X} by A1,A2;
    end;
    then
A4:  {x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X} c=
    {x+U where U is Subset of X:U in O & U in NeighborhoodSystem 0.X};
    now
      let t be object;
      assume t in {x+U where U is Subset of X:U in O &
      U in NeighborhoodSystem 0.X};
      then consider U1 be Subset of X such that
A5:   t=x+U1 and
A6:   U1 in O and
A7:   U1 in NeighborhoodSystem 0.X;
      U1 is a_neighborhood of 0.X by A7,YELLOW19:2;
      hence t in {x+U where U is Subset of X:U in O &
      U is a_neighborhood of 0.X} by A5,A6;
    end;
    then {x+U where U is Subset of X:U in O & U in NeighborhoodSystem 0.X} c=
    {x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X};
    hence thesis by A4;
end;

theorem Th10:
  for X being non empty LinearTopSpace,
      x being Point of X,
      O being local_base of X,
      B being Subset-Family of X st
  B = {x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X} holds
  B is basis of BOOL2F NeighborhoodSystem x
  proof
    let X be non empty LinearTopSpace,
    x be Point of X, O be local_base of X,B be Subset-Family of X;
    assume
A1: B={x+U where U is Subset of X:U in O & U is a_neighborhood of 0.X};
    set F=BOOL2F NeighborhoodSystem x;
A2: F c= <.B.]
    proof
      now
        let t be object;
        assume t in F;
        then t in NeighborhoodSystem x by CARDFIL2:def 20;
        then t in the set of all A where
        A is a_neighborhood of x by YELLOW19:def 1;
        then consider A be a_neighborhood of x such that
A3:     t=A;
        x in Int(A) by CONNSP_2:def 1;
        then -x+Int(A) is a_neighborhood of 0.X by RLTOPSP1:9,CONNSP_2:3;
        then consider V being a_neighborhood of 0.X such that
A4:     V in O and
A5:     V c= -x+Int(A) by YELLOW13:def 2;
        set U = x+V;
A6:     U in B by A1,A4;
        U c= x+(-x+Int(A)) by A5,RLTOPSP1:8;
        then U c= x+(-x)+Int(A) by RLTOPSP1:6;
        then U c= 0.X+Int(A) by RLVECT_1:5;
        then Int(A) c= A & U c= Int(A) by RLTOPSP1:5,TOPS_1:16;
        then U c= A;
        hence t in <.B.] by A3,A6,CARDFIL2:def 8;
      end;
      hence thesis;
    end;
    <.B.] c= F
    proof
      now
        let t be object;
        assume
A7:     t in <.B.];
        then reconsider t1=t as Subset of X;
        consider b be Element of B such that
A8:     b c= t1 by A7,CARDFIL2:def 8;
        set v0 = the Element of O;
        B is non empty by A1,Lm2;
        then b in B;
        then consider U1 be Subset of X such that
A9:     b=x+U1 and
        U1 in O and
A10:    U1 is a_neighborhood of 0.X by A1;
        reconsider t2=b as Element of B;
A11:    x+0.X in x+Int(U1) by Lm1, A10,CONNSP_2:def 1;
        x+Int(U1) c= Int(x+U1) by RLTOPSP1:37;
        then t2 is a_neighborhood of x by A9,A11,CONNSP_2:def 1;
        then t2 in the set of all A where
        A is a_neighborhood of x;
        then t2 in NeighborhoodSystem x by YELLOW19:def 1;
        then t2 in F by CARDFIL2:def 20;
        hence t in F by A8,CARD_FIL:def 1;
      end;
      hence thesis;
    end;
    hence thesis by CARDFIL2:22,A2,XBOOLE_0:def 10;
  end;

theorem
  for X being non empty LinearTopSpace,
      s being sequence of the carrier of X,
      x being Point of X,
      V being local_base of X,
      B being Subset-Family of X st
  B={x+U where U is Subset of X:U in V & U is a_neighborhood of 0.X} holds
  x in lim_f s
    iff
  for v being Element of B holds ex i being Nat st
  for j being Nat st i <=j holds s.j in v
  proof
    let X be non empty LinearTopSpace,
    s be sequence of the carrier of X,
    x be Point of X, V be local_base of X,B be
    Subset-Family of X;
    assume B={x+U where U is Subset of X:U in V &
    U is a_neighborhood of 0.X};
    then B is basis of BOOL2F NeighborhoodSystem x by Th10;
    hence x in lim_f s iff
    for b be Element of B ex i be Nat st
    for j be Nat st i <=j holds s.j in b by CARDFIL2:97;
  end;

theorem
  for X being non empty LinearTopSpace,
      s being sequence of the carrier of X,
      x being Point of X,
      V being local_base of X holds
  x in lim_f s
    iff
  for v being Subset of X st v in (V /\ NeighborhoodSystem 0.X) holds
  ex i being Nat st for j being Nat st i <= j holds s.j in x+v
  proof
    let X be non empty LinearTopSpace,
    s be sequence of the carrier of X,
    x be Point of X, V be local_base of X;
    set B={x+U where U is Subset of X:U in V &
    U is a_neighborhood of 0.X};
    reconsider B as Subset-Family of X by Lm2;
A1: B is basis of BOOL2F NeighborhoodSystem x by Th10;
    hereby
      assume
A2:   x in lim_f s;
      let v be Subset of X;
      assume v in V/\NeighborhoodSystem 0.X;
      then v in V & v in NeighborhoodSystem 0.X by XBOOLE_0: def 4;
      then v in V & v is a_neighborhood of 0.X by YELLOW19:2;
      then x+v in B;
      then reconsider b=x+v as Element of B;
      consider i0 be Nat such that
A3:   for j be Nat st i0 <= j holds s.j in b by A2,A1,CARDFIL2:97;
      thus ex i be Nat st for j be Nat st i <=j holds s.j in x+v by A3;
    end;
    assume
A4: for v be Subset of X st v in (V/\NeighborhoodSystem 0.X) holds
    ex i be Nat st for j be Nat st i <=j holds s.j in x+v;
    for b be Element of B ex i be Nat st
    for j be Nat st i <=j holds s.j in b
    proof
      let b be Element of B;
      B is non empty by Lm2;
      then b in B;
      then consider U1 be Subset of X such that
A5:   b=x+U1 and
A6:   U1 in V and
A7:   U1 is a_neighborhood of 0.X;
      U1 in NeighborhoodSystem 0.X by A7,YELLOW19:2;
      then U1 in (V/\NeighborhoodSystem 0.X) by A6,XBOOLE_0:def 4;
      then consider i0 be Nat such that
A8:   for j be Nat st i0 <= j holds s.j in x+U1 by A4;
      take i0;
      thus thesis by A5,A8;
    end;
    hence x in lim_f s by A1,CARDFIL2:97;
  end;

theorem
  for T being non empty LinearTopSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of T,
      x being Point of T,
      B being basis of BOOL2F NeighborhoodSystem x st [#]L is directed holds
  x in lim_f f
    iff
  for b being Element of B ex i be Element of L st
  for j being Element of L st i <=j holds f.j in b by CARDFIL2:84;

Lm3:
  for T being non empty LinearTopSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of T,
      x being Point of T,
      V being local_base of T,
      B being Subset-Family of T st [#]L is directed &
      B={x+U where U is Subset of T:U in V & U is a_neighborhood of 0.T} holds
  x in lim_f f
    iff
  for b being Element of B ex i being Element of L st
  for j being Element of L st i <=j holds f.j in b
  proof
    let T be non empty LinearTopSpace,
    L be non empty transitive reflexive RelStr,
    f be Function of [#]L,the carrier of T, x be Point of T,
    V be local_base of T, B being Subset-Family of T;
    assume that
A1: [#]L is directed and
A2: B={x+U where U is Subset of T:U in V & U is a_neighborhood of 0.T};
    reconsider B1=B as basis of BOOL2F NeighborhoodSystem x by A2,Th10;
    x in lim_f f iff
    for b be Element of B1 ex i be Element of L st
    for j be Element of L st i <=j holds f.j in b by A1,CARDFIL2:84;
    hence thesis;
  end;

theorem
  for T being non empty LinearTopSpace,
      L being non empty transitive reflexive RelStr,
      f being Function of [#]L,the carrier of T,
      x being Point of T,
      V being local_base of T st [#]L is directed holds
  x in lim_f f
    iff
  (for v being Subset of T st v in (V/\NeighborhoodSystem 0.T)
  ex i being Element of L st for j being Element of L st i <=j holds
    f.j in x+v)
  proof
    let T be non empty LinearTopSpace,
    L be non empty transitive reflexive RelStr,
    f be Function of [#]L,the carrier of T,
    x be Point of T, V be local_base of T;
    assume
A1: [#]L is directed;
    set B={x+U where U is Subset of T:U in V &
    U is a_neighborhood of 0.T};
    reconsider B as Subset-Family of T by Lm2;
    now
      hereby
        assume
A2:     x in lim_f f;
        let v be Subset of T;
        assume v in (V/\NeighborhoodSystem 0.T);
        then v in V & v in NeighborhoodSystem 0.T by XBOOLE_0: def 4;
        then v in V & v is a_neighborhood of 0.T by YELLOW19:2;
        then x+v in B;
        then reconsider b=x+v as Element of B;
        consider i0 be Element of L such that
A3:     for j be Element of L st i0 <= j holds f.j in b
        by A1,A2,Lm3;
        take i0;
        thus for j be Element of L st i0 <=j holds f.j in x+v by A3;
      end;
      assume
A4:   for v be Subset of T st v in (V/\NeighborhoodSystem 0.T)
      ex i be Element of L st for j be Element of L st i <=j holds f.j in x+v;
      for b be Element of B ex i be Element of L st
      for j be Element of L st i <=j holds f.j in b
      proof
        let b be Element of B;
        B is non empty by Lm2;
        then b in B;
        then consider U1 be Subset of T such that
A5:     b=x+U1 and
A6:     U1 in V and
A7:     U1 is a_neighborhood of 0.T;
        U1 in NeighborhoodSystem 0.T by A7,YELLOW19:2;
        then U1 in (V/\NeighborhoodSystem 0.T) by A6,XBOOLE_0:def 4;
        then consider i0 be Element of L such that
A8:     for j be Element of L st i0 <= j holds f.j in x+U1 by A4;
        take i0;
        thus thesis by A5,A8;
      end;
      hence x in lim_f f by A1,Lm3;
    end;
    hence thesis;
  end;

begin :: Partial sum in Abgroup (Abelian AddGroup)

definition
  let I being non empty set,
      L being AbGroup,
      x being (the carrier of L)-valued ManySortedSet of I,
      J being Element of Fin I;
  func Sum(x,J) ->Element of L means
:Def1:
  ex p being one-to-one FinSequence of I st rng p = J &
  it = (the addF of L) "**" #(p,x);
  existence
  proof
    consider p be FinSequence of I such that
A1: rng p = J & p is one-to-one by Th1;
    (the addF of L) "**" #(p,x) is Element of L;
    hence thesis by A1;
  end;
  uniqueness
  proof
    let X1,X2 be Element of L such that
A2: ex p1 be one-to-one FinSequence of I st rng p1 = J &
    X1 = (the addF of L) "**"  #(p1,x) and
A3: ex p2 be one-to-one FinSequence of I st rng p2 = J &
    X2 = (the addF of L) "**" #(p2,x);
    consider p1 be one-to-one FinSequence of I such that
A4: rng p1 = J and
A5: X1 = (the addF of L) "**" #(p1,x) by A2;
    consider p2 be one-to-one FinSequence of I such that
A6: rng p2 = J and
A7: X2 = (the addF of L) "**" #(p2,x) by A3;
    consider P be Permutation of dom p1 such that
A8: p2=P*p1 & dom P=dom p1 & rng P=dom p1 by A4,A6,BHSP_5:1;
    P is Permutation of dom #(p1,x)
    proof
      dom x =I by PARTFUN1:def 2;
      then rng p1 c= dom x by FINSEQ_1:def 4;
      then dom (p1 * x)=dom p1 by RELAT_1:27;
      hence thesis;
    end;
    then reconsider P as Permutation of dom #(p1,x);
    #(p2,x) = P * #(p1,x)
    proof
    now
      hereby
        let t be object;
        assume
A9:     t in #(p2,x);
        consider a,b be object such that
A10:    t=[a,b] by A9,RELAT_1:def 1;
        consider z be object such that
A11:    [a,z] in p2 and
A12:    [z,b] in x by A9,A10,RELAT_1:def 8;
        consider y be object such that
A13:    [a,y] in P and
A14:    [y,z] in p1 by A11,A8,RELAT_1:def 8;
        [a,y] in P & [y,b] in p1 * x by A13,A12,A14,RELAT_1:def 8;
        hence t in P * #(p1,x) by A10,RELAT_1:def 8;
        end;
        let t be object;
        assume
A15:    t in P* #(p1,x);
        consider a,b be object such that
A16:    t=[a,b] by A15,RELAT_1:def 1;
        consider c be object such that
A17:    [a,c] in P and
A18:    [c,b] in p1*x by A15,A16,RELAT_1:def 8;
        consider d be object such that
A19:    [c,d] in p1  and
A20:    [d,b] in x by A18,RELAT_1:def 8;
        [a,d] in p2 by A8,RELAT_1:def 8,A17,A19;
        hence t in #(p2,x) by A16,A20,RELAT_1:def 8;
      end;
      hence thesis;
    end;
    hence thesis by A5,A7,FVSUM_1:8,FINSOP_1:7;
  end;
end;

theorem
  for I being non empty set,
      L being AbGroup,
      x being (the carrier of L)-valued ManySortedSet of I,
      J being Element of Fin I holds
  for e being Element of Fin I st e={} holds
    Sum(x,e)=0.L &
    for e,f being Element of Fin I st e misses f holds
    Sum(x,e\/f)=Sum(x,e)+Sum(x,f)
  proof
    let I be non empty set,
    L be AbGroup,
    x be (the carrier of L)-valued ManySortedSet of I,
    J be Element of Fin I;
A1: now
      let e be Element of Fin I;
      assume
A2:   e={};
      consider p be one-to-one FinSequence of I  such that
A3:   rng p = e and
A4:   Sum(x,e)=(the addF of L) "**" #(p,x) by Def1;
      p={} by A3,A2;
      then #(p,x)={} & the addF of L is having_a_unity &
      len #(p,x) =0 by FVSUM_1:8;
      then Sum(x,e)=the_unity_wrt the addF of L by A4,FINSOP_1:def 1;
      hence Sum(x,e)=0.L by FVSUM_1:7;
    end;
    now
      let e,f be Element of Fin I;
      assume
A5:   e misses f;
      consider pe be one-to-one FinSequence of I  such that
A6:   rng pe = e and
A7:   Sum(x,e)=(the addF of L) "**" #(pe,x) by Def1;
      consider pf be one-to-one FinSequence of I  such that
A8:   rng pf = f and
A9:   Sum(x,f)=(the addF of L) "**" #(pf,x) by Def1;
      reconsider pepf=pe^pf as one-to-one FinSequence of I
      by A5,A6,A8,FINSEQ_3:91;
A10:   #(pepf,x)=#(pe,x)^#(pf,x) by Th3;
      rng pepf=e\/f by A6,A8,FINSEQ_1:31;
      then Sum(x,e\/f)=(the addF of L) "**" #(pepf,x) by Def1;
      hence Sum(x,e\/f)=Sum(x,e)+Sum(x,f)
      by A7,A9,A10,FINSOP_1:5,FVSUM_1:8;
    end;
    hence thesis by A1;
  end;

definition
  let I be non empty set,
      L be AbGroup,
      x be (the carrier of L)-valued ManySortedSet of I;
  func Partial_Sums(x) -> Function of [#]OrderedFIN I,the carrier of L means
  for j being Element of Fin I holds it.j = Sum(x,j);
  existence
  proof
    deffunc F(Element of Fin I)=Sum(x,$1);
    consider f be Function of Fin I,the carrier of L such that
A1: for t be Element of Fin I holds f.t=F(t)
    from FUNCT_2:sch 4;
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then
A2: [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    reconsider f as Function of [#]OrderedFIN I, the carrier of L by A2;
    for j be Element of Fin I holds f.j=Sum(x,j) by A1;
    hence thesis;
  end;
  uniqueness
  proof
    deffunc F(Element of Fin I)=Sum(x,$1);
A3: for a,b being Function of Fin I,the carrier of L st (for q being
    Element of Fin I holds a.q=F(q)) & (for q being Element of Fin I holds b.
    q=F(q)) holds a=b from BINOP_2:sch 1;
    let f,g be Function of [#]OrderedFIN I,the carrier of L;
    assume that
A4: for j be Element of Fin I holds f.j=Sum(x,j) and
A5: for j be Element of Fin I holds g.j=Sum(x,j);
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    then reconsider f,g as Function of Fin I,the carrier of L;
    f=g by A3,A4,A5;
    hence thesis;
  end;
end;

begin :: Product of family as limit in commutative Topological Group

definition
  let I be non empty set,
      L be commutative TopGroup,
      x be (the carrier of L)-valued ManySortedSet of I,
      J be Element of Fin I;
  func Product(x,J) -> Element of L means
:Def2:
  ex p being one-to-one FinSequence of I st rng p = J &
  it = (the multF of L) "**" #(p,x);
  existence
  proof
    consider p be FinSequence of I such that
A1: rng p = J & p is one-to-one by Th1;
    (the multF of L) "**" #(p,x) is Element of L;
    hence thesis by A1;
  end;
  uniqueness
  proof
    let X1,X2 be Element of L such that
A2: ex p1 be one-to-one FinSequence of I st rng p1 = J &
    X1 = (the multF of L) "**"  #(p1,x) and
A3: ex p2 be one-to-one FinSequence of I st rng p2 = J &
    X2 = (the multF of L) "**" #(p2,x);
    consider p1 be one-to-one FinSequence of I such that
A4: rng p1 = J and
A5: X1 = (the multF of L) "**" #(p1,x) by A2;
    consider p2 be one-to-one FinSequence of I such that
A6: rng p2 = J and
A7: X2 = (the multF of L) "**" #(p2,x) by A3;
    consider P be Permutation of dom p1 such that
A8: p2=P*p1 & dom P=dom p1 & rng P=dom p1 by A4,A6,BHSP_5:1;
    P is Permutation of dom #(p1,x)
    proof
      dom x =I by PARTFUN1:def 2;
      then rng p1 c= dom x by FINSEQ_1:def 4;
      then dom (p1 * x)=dom p1 by RELAT_1:27;
      hence thesis;
    end;
    then reconsider P as Permutation of dom #(p1,x);
    #(p2,x) = P * #(p1,x)
    proof
      now
        hereby
          let t be object;
          assume
A9:       t in #(p2,x);
          consider a,b be object such that
A10:      t=[a,b] by A9,RELAT_1:def 1;
          consider z be object such that
A11:      [a,z] in p2 and
A12:      [z,b] in x by A9,A10,RELAT_1:def 8;
          consider y be object such that
A13:      [a,y] in P and
A14:      [y,z] in p1 by A11,A8,RELAT_1:def 8;
          [a,y] in P & [y,b] in p1 * x by A13,A12,A14,RELAT_1:def 8;
          hence t in P * #(p1,x) by A10,RELAT_1:def 8;
        end;
        let t be object;
        assume
A15:    t in P* #(p1,x);
        consider a,b be object such that
A16:    t=[a,b] by A15,RELAT_1:def 1;
        consider c be object such that
A17:    [a,c] in P and
A18:    [c,b] in p1*x by A15,A16,RELAT_1:def 8;
        consider d be object such that
A19:    [c,d] in p1  and
A20:    [d,b] in x by A18,RELAT_1:def 8;
        [a,d] in p2 by A8,RELAT_1:def 8,A17,A19;
        hence t in #(p2,x) by A16,A20,RELAT_1:def 8;
      end;
      hence thesis;
    end;
    hence thesis by A5,A7,FINSOP_1:7;
  end;
end;

theorem Th11:
  for I being set,
      G being TopGroup,
      f being Function of [#]OrderedFIN I,the carrier of G,
      x being Point of G,
      B being basis of BOOL2F NeighborhoodSystem x holds
  x in lim_f f
    iff
  for b being Element of B ex i be Element of OrderedFIN I st
  for j being Element of OrderedFIN I st i <= j holds f.j in b
  proof
    let I be set,G be TopGroup,
    f be Function of [#]OrderedFIN I,the carrier of G,
    x be Point of G,
    B be basis of BOOL2F NeighborhoodSystem x;
    [#]OrderedFIN I is directed by Th4;
    hence thesis by CARDFIL2:84;
  end;

theorem
  for I being non empty set,
      L being commutative TopGroup,
      x being (the carrier of L)-valued ManySortedSet of I,
      J being Element of Fin I holds
  for e being Element of Fin I st e={} holds
    Product(x,e)=1_L &
    for e,f being Element of Fin I st e misses f holds
    Product(x,e\/f)=Product(x,e) * Product(x,f)
  proof
    let I be non empty set,
    L be commutative TopGroup,
    x be (the carrier of L)-valued ManySortedSet of I,
    J be Element of Fin I;
A1: now
      let e be Element of Fin I;
      assume
A2:   e={};
      consider p be one-to-one FinSequence of I  such that
A3:   rng p = e and
A4:   Product(x,e)=(the multF of L) "**" #(p,x) by Def2;
      p={} by A3,A2;
      then #(p,x)={} & the multF of L is having_a_unity &
      len #(p,x) =0;
      then Product(x,e)=the_unity_wrt the multF of L by A4,FINSOP_1:def 1;
      hence Product(x,e)=1_L by GROUP_1:22;
    end;
    now
      let e,f be Element of Fin I;
      assume
A5:   e misses f;
      consider pe be one-to-one FinSequence of I  such that
A6:   rng pe = e and
A7:   Product(x,e)=(the multF of L) "**" #(pe,x) by Def2;
      consider pf be one-to-one FinSequence of I  such that
A8:   rng pf = f and
A9:   Product(x,f)=(the multF of L) "**" #(pf,x) by Def2;
      reconsider pepf=pe^pf as one-to-one FinSequence of I
      by A5,A6,A8,FINSEQ_3:91;
A10:  #(pepf,x)=#(pe,x)^#(pf,x) by Th3;
      rng pepf=e\/f by A6,A8,FINSEQ_1:31; then
      Product(x,e\/f)=(the multF of L) "**" #(pepf,x) by Def2;
      hence Product(x,e\/f)=Product(x,e) * Product(x,f)
      by A7,A9,A10,FINSOP_1:5;
    end;
    hence thesis by A1;
  end;

definition
  let I be non empty set,
      L be commutative TopGroup,
      x be (the carrier of L)-valued ManySortedSet of I;
  func Partial_Product(x) -> Function of [#]OrderedFIN I,the carrier of L means
  for j being Element of Fin I holds it.j=Product(x,j);
  existence
  proof
    deffunc F(Element of Fin I)=Product(x,$1);
    consider f be Function of Fin I,the carrier of L such that
A1: for t be Element of Fin I holds f.t=F(t) from FUNCT_2:sch 4;
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    then reconsider f as Function of [#]OrderedFIN I, the carrier of L;
    for j be Element of Fin I holds f.j=Product(x,j) by A1;
    hence thesis;
  end;
  uniqueness
  proof
    deffunc F(Element of Fin I)=Product(x,$1);
A2: for a,b being Function of Fin I,the carrier of L st (for q being
    Element of Fin I holds a.q=F(q)) & (for q being Element of Fin I holds b.
    q=F(q)) holds a=b from BINOP_2:sch 1;
    let f,g be Function of [#]OrderedFIN I,the carrier of L;
    assume that
A3: for j be Element of Fin I holds f.j=Product(x,j) and
A4: for j be Element of Fin I holds g.j=Product(x,j);
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    then reconsider f,g as Function of Fin I,the carrier of L;
    f=g by A2,A3,A4;
    hence thesis;
  end;
end;

theorem
  for I being non empty set,
      G being commutative TopGroup,
      s being (the carrier of G)-valued ManySortedSet of I,
      x being Point of G,
      B being basis of BOOL2F NeighborhoodSystem x holds
  x in lim_f Partial_Product(s)
    iff
  for b being Element of B ex i be Element of OrderedFIN I st
  for j being Element of OrderedFIN I st i <= j holds
  (Partial_Product(s)).j in b by Th11;

begin :: Summable family in commutative topological group

definition
  let I be non empty set,
      L be Abelian TopaddGroup,
      x be (the carrier of L)-valued ManySortedSet of I,
      J be Element of Fin I;
  func Sum(x,J) -> Element of L means
:Def3:
  ex p being one-to-one FinSequence of I st rng p = J &
  it = (the addF of L) "**" #(p,x);
  existence
  proof
    consider p be FinSequence of I such that
A1: rng p = J & p is one-to-one by Th1;
    (the addF of L) "**" #(p,x) is Element of L;
    hence thesis by A1;
  end;
  uniqueness
  proof
    let X1,X2 be Element of L such that
A2: ex p1 be one-to-one FinSequence of I st rng p1 = J &
    X1 = (the addF of L) "**"  #(p1,x) and
A3: ex p2 be one-to-one FinSequence of I st rng p2 = J &
    X2 = (the addF of L) "**" #(p2,x);
    consider p1 be one-to-one FinSequence of I such that
A4: rng p1 = J and
A5: X1 = (the addF of L) "**" #(p1,x) by A2;
    consider p2 be one-to-one FinSequence of I such that
A6: rng p2 = J and
A7: X2 = (the addF of L) "**" #(p2,x) by A3;
    consider P be Permutation of dom p1 such that
A8: p2=P*p1 & dom P=dom p1 & rng P=dom p1 by A4,A6,BHSP_5:1;
    P is Permutation of dom #(p1,x)
    proof
      dom x =I by PARTFUN1:def 2;
      then rng p1 c= dom x by FINSEQ_1:def 4;
      then dom (p1 * x)=dom p1 by RELAT_1:27;
      hence thesis;
    end;
    then reconsider P as Permutation of dom #(p1,x);
A9: #(p2,x) = P * #(p1,x)
    proof
      now
        hereby
          let t be object;
          assume
A10:      t in #(p2,x);
          consider a,b be object such that
A11:      t=[a,b] by A10,RELAT_1:def 1;
          consider z be object such that
A12:      [a,z] in p2 and
A13:      [z,b] in x by A10,A11,RELAT_1:def 8;
          consider y be object such that
A14:      [a,y] in P and
A15:      [y,z] in p1 by A12,A8,RELAT_1:def 8;
          [a,y] in P & [y,b] in p1 * x by A14,A13,A15,RELAT_1:def 8;
          hence t in P * #(p1,x) by A11,RELAT_1:def 8;
        end;
        let t be object;
        assume
A16:    t in P* #(p1,x);
        then consider a,b be object such that
A17:    t=[a,b] by RELAT_1:def 1;
        consider c be object such that
A18:    [a,c] in P and
A19:    [c,b] in p1*x by A16,A17,RELAT_1:def 8;
        consider d be object such that
A20:    [c,d] in p1 and
A21:    [d,b] in x by A19,RELAT_1:def 8;
        [a,d] in p2 by A8,RELAT_1:def 8,A18,A20;
        hence t in #(p2,x) by A17,A21,RELAT_1:def 8;
      end;
      hence thesis;
    end;
    the addF of L is commutative by GROUP_1A:203;
    hence thesis by A9,A5,A7,FINSOP_1:7;
  end;
end;

theorem Th12:
  for I being set,
      G being TopaddGroup,
      f being Function of [#]OrderedFIN I,the carrier of G,
      x being Point of G,
      B being basis of BOOL2F NeighborhoodSystem x holds
  x in lim_f f
    iff
  for b being Element of B ex i being Element of OrderedFIN I st
  for j being Element of OrderedFIN I st i <= j holds f.j in b
  proof
    let I be set,G be TopaddGroup,
    f be Function of [#]OrderedFIN I,the carrier of G,
    x be Point of G,
    B be basis of BOOL2F NeighborhoodSystem x;
    [#]OrderedFIN I is directed by Th4;
    hence thesis by CARDFIL2:84;
  end;

theorem
  for I being non empty set,
      L being Abelian TopaddGroup,
      x being (the carrier of L)-valued ManySortedSet of I,
      J being Element of Fin I holds
  for e being Element of Fin I st e={} holds
    Sum(x,e)=0_L &
    for e,f being Element of Fin I st e misses f holds
    Sum(x,e\/f)=Sum(x,e) + Sum(x,f)
  proof
    let I be non empty set,
    L be Abelian TopaddGroup,
    x be (the carrier of L)-valued ManySortedSet of I,
    J be Element of Fin I;
A1: now
      let e be Element of Fin I;
      assume
A2:   e={};
      consider p be one-to-one FinSequence of I  such that
A3:   rng p = e and
A4:   Sum(x,e)=(the addF of L) "**" #(p,x) by Def3;
      p={} by A3,A2;
      then #(p,x)={} & the addF of L is having_a_unity &
      len #(p,x) =0;
      then Sum(x,e)=the_unity_wrt the addF of L by A4,FINSOP_1:def 1;
      hence Sum(x,e)=0_L by GROUP_1A:21;
    end;
    now
      let e,f be Element of Fin I;
      assume
A5:   e misses f;
      consider pe be one-to-one FinSequence of I such that
A6:   rng pe = e and
A7:   Sum(x,e)=(the addF of L) "**" #(pe,x) by Def3;
      consider pf be one-to-one FinSequence of I  such that
A8:   rng pf = f and
A9:   Sum(x,f)=(the addF of L) "**" #(pf,x) by Def3;
      reconsider pepf=pe^pf as one-to-one FinSequence of I
      by A5,A6,A8,FINSEQ_3:91;
A10:  #(pepf,x)=#(pe,x)^#(pf,x) by Th3;
      rng pepf=e\/f by A6,A8,FINSEQ_1:31;
      then
      Sum(x,e\/f)=(the addF of L) "**" #(pepf,x) by Def3;
      hence Sum(x,e\/f)=Sum(x,e) + Sum(x,f) by A7,A9,A10,FINSOP_1:5;
    end;
    hence thesis by A1;
  end;

definition
  let I be non empty set,
      L be Abelian TopaddGroup,
      x be (the carrier of L)-valued ManySortedSet of I;
  func Partial_Sums(x) -> Function of [#]OrderedFIN I,the carrier of L means
  for j being Element of Fin I holds it.j=Sum(x,j);
  existence
  proof
    deffunc F(Element of Fin I)=Sum(x,$1);
    consider f be Function of Fin I,the carrier of L such that
A1: for t be Element of Fin I holds f.t=F(t)
    from FUNCT_2:sch 4;
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then
    [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    then reconsider f as Function of [#]OrderedFIN I, the carrier of L;
    for j be Element of Fin I holds f.j=Sum(x,j) by A1;
    hence thesis;
  end;
  uniqueness
  proof
    deffunc F(Element of Fin I)=Sum(x,$1);
A2: for a,b being Function of Fin I,the carrier of L st (for q being
    Element of Fin I holds a.q=F(q)) & (for q being Element of Fin I holds b.
    q=F(q)) holds a=b from BINOP_2:sch 1;
    let f,g be Function of [#]OrderedFIN I,the carrier of L;
    assume that
A3: for j be Element of Fin I holds f.j=Sum(x,j) and
A4: for j be Element of Fin I holds g.j=Sum(x,j);
    the carrier of OrderedFIN I= Fin I by YELLOW_1:1;
    then [#]OrderedFIN I= Fin I by STRUCT_0:def 3;
    then reconsider f,g as Function of Fin I,the carrier of L;
    f=g by A2,A3,A4;
    hence thesis;
  end;
end;

theorem
  for I being non empty set,
      G being Abelian TopaddGroup,
      s being (the carrier of G)-valued ManySortedSet of I,
      x being Point of G,
      B being basis of BOOL2F NeighborhoodSystem x holds
  x in lim_f Partial_Sums(s)
    iff
  for b being Element of B ex i being Element of OrderedFIN I st
  for j being Element of OrderedFIN I st i <= j holds (Partial_Sums(s)).j in b
  by Th12;