flang_2.miz



    begin

    reserve E,x,y,X for set;

    reserve A,B,C for Subset of (E ^omega );

    reserve a,b for Element of (E ^omega );

    reserve i,k,l,kl,m,n,mn for Nat;

    theorem :: FLANG_2:1

    

     Th1: (m + k) <= i & i <= (n + k) implies ex mn st (mn + k) = i & m <= mn & mn <= n

    proof

      assume that

       A1: (m + k) <= i and

       A2: i <= (n + k);

      (m + k) <= (m + i) by A1, XREAL_1: 38;

      then k <= i by XREAL_1: 6;

      then

      reconsider mn = (i - k) as Nat by NAT_1: 21;

      take mn;

      thus (mn + k) = i;

      (m + k) <= (mn + k) by A1;

      hence thesis by A2, XREAL_1: 6;

    end;

    theorem :: FLANG_2:2

    

     Th2: m <= n & k <= l & (m + k) <= i & i <= (n + l) implies ex mn, kl st (mn + kl) = i & m <= mn & mn <= n & k <= kl & kl <= l

    proof

      assume that

       A1: m <= n and

       A2: k <= l and

       A3: (m + k) <= i and

       A4: i <= (n + l);

      per cases ;

        suppose i <= (n + k);

        then

        consider mn such that

         A5: (mn + k) = i & m <= mn & mn <= n by A3, Th1;

        take mn, k;

        thus (mn + k) = i & m <= mn & mn <= n by A5;

        thus thesis by A2;

      end;

        suppose i > (n + k);

        then

        consider kl such that

         A6: (kl + n) = i and

         A7: k <= kl & kl <= l by A4, Th1;

        take n, kl;

        thus (n + kl) = i & m <= n & n <= n by A1, A6;

        thus thesis by A7;

      end;

    end;

    theorem :: FLANG_2:3

    

     Th3: m < n implies ex k st (m + k) = n & k > 0

    proof

      assume m < n;

      then (ex k st (m + k) = n) & (m - m) < (n - m) by NAT_1: 10, XREAL_1: 14;

      hence thesis;

    end;

    theorem :: FLANG_2:4

    

     Th4: (a ^ b) = a or (b ^ a) = a implies b = {}

    proof

      assume

       A1: (a ^ b) = a or (b ^ a) = a;

      per cases by A1;

        suppose

         A2: (a ^ b) = a;

        ( len (a ^ b)) = (( len a) + ( len b)) by AFINSQ_1: 17;

        hence thesis by A2;

      end;

        suppose

         A3: (b ^ a) = a;

        ( len (b ^ a)) = (( len b) + ( len a)) by AFINSQ_1: 17;

        hence thesis by A3;

      end;

    end;

    begin

    theorem :: FLANG_2:5

    (x in A or x in B) & x <> ( <%> E) implies (A ^^ B) <> {( <%> E)}

    proof

      assume (x in A or x in B) & x <> ( <%> E);

      then A <> {( <%> E)} or B <> {( <%> E)} by TARSKI:def 1;

      hence thesis by FLANG_1: 14;

    end;

    theorem :: FLANG_2:6

     <%x%> in (A ^^ B) iff ( <%> E) in A & <%x%> in B or <%x%> in A & ( <%> E) in B

    proof

      thus <%x%> in (A ^^ B) implies ( <%> E) in A & <%x%> in B or <%x%> in A & ( <%> E) in B

      proof

        assume <%x%> in (A ^^ B);

        then ex a, b st a in A & b in B & <%x%> = (a ^ b) by FLANG_1:def 1;

        hence thesis by FLANG_1: 4;

      end;

      

       A1: ( {} ^ <%x%>) = <%x%> & ( <%x%> ^ {} ) = <%x%>;

      assume ( <%> E) in A & <%x%> in B or <%x%> in A & ( <%> E) in B;

      hence thesis by A1, FLANG_1:def 1;

    end;

    theorem :: FLANG_2:7

    

     Th7: x in A & x <> ( <%> E) & n > 0 implies (A |^ n) <> {( <%> E)}

    proof

      assume that

       A1: x in A & x <> ( <%> E) and

       A2: n > 0 ;

      A <> {( <%> E)} by A1, TARSKI:def 1;

      hence thesis by A2, FLANG_1: 29;

    end;

    theorem :: FLANG_2:8

    ( <%> E) in (A |^ n) iff n = 0 or ( <%> E) in A

    proof

      thus ( <%> E) in (A |^ n) implies n = 0 or ( <%> E) in A by FLANG_1: 31;

      assume

       A1: n = 0 or ( <%> E) in A;

      per cases by A1;

        suppose n = 0 ;

        then (A |^ n) = {( <%> E)} by FLANG_1: 29;

        hence thesis by ZFMISC_1: 31;

      end;

        suppose ( <%> E) in A;

        hence thesis by FLANG_1: 30;

      end;

    end;

    theorem :: FLANG_2:9

    

     Th9: <%x%> in (A |^ n) iff <%x%> in A & (( <%> E) in A & n > 1 or n = 1)

    proof

      thus <%x%> in (A |^ n) implies <%x%> in A & (( <%> E) in A & n > 1 or n = 1)

      proof

        assume

         A1: <%x%> in (A |^ n);

        (A |^ n) c= (A * ) by FLANG_1: 42;

        hence <%x%> in A by A1, FLANG_1: 72;

        assume

         A2: ( not ( <%> E) in A or n <= 1) & n <> 1;

        per cases by A2;

          suppose

           A3: not ( <%> E) in A & n <> 1;

          per cases by A3, NAT_1: 25;

            suppose n = 0 ;

            then (A |^ n) = {( <%> E)} by FLANG_1: 24;

            hence contradiction by A1, TARSKI:def 1;

          end;

            suppose

             A4: n > 1;

            then

            consider m such that

             A5: (m + 1) = n by NAT_1: 6;

             <%x%> in ((A |^ m) ^^ A) by A1, A5, FLANG_1: 23;

            then

            consider a, b such that

             A6: a in (A |^ m) and

             A7: b in A and

             A8: <%x%> = (a ^ b) by FLANG_1:def 1;

            per cases by A8, FLANG_1: 4;

              suppose

               A9: a = ( <%> E) & b = <%x%>;

              (m + 1) > ( 0 + 1) by A4, A5;

              then m > 0 ;

              hence contradiction by A3, A6, A9, FLANG_1: 31;

            end;

              suppose b = ( <%> E) & a = <%x%>;

              hence contradiction by A3, A7;

            end;

          end;

        end;

          suppose n <= 1 & n <> 1;

          then n = 0 by NAT_1: 25;

          then (A |^ n) = {( <%> E)} by FLANG_1: 24;

          hence contradiction by A1, TARSKI:def 1;

        end;

      end;

      assume that

       A10: <%x%> in A and

       A11: ( <%> E) in A & n > 1 or n = 1;

      per cases by A11;

        suppose ( <%> E) in A & n > 1;

        then A c= (A |^ n) by FLANG_1: 35;

        hence thesis by A10;

      end;

        suppose n = 1;

        hence thesis by A10, FLANG_1: 25;

      end;

    end;

    theorem :: FLANG_2:10

    

     Th10: m <> n & (A |^ m) = {x} & (A |^ n) = {x} implies x = ( <%> E)

    proof

      assume that

       A1: m <> n and

       A2: (A |^ m) = {x} and

       A3: (A |^ n) = {x};

      

       A4: x in (A |^ m) by A2, TARSKI:def 1;

      

       A5: x in (A |^ n) by A3, TARSKI:def 1;

      per cases by A1, XXREAL_0: 1;

        suppose m > n;

        then

        consider k such that

         A6: (n + k) = m and

         A7: k > 0 by Th3;

        ((A |^ n) ^^ (A |^ k)) = (A |^ m) by A6, FLANG_1: 33;

        then

        consider a, b such that

         A8: a in (A |^ n) and

         A9: b in (A |^ k) and

         A10: x = (a ^ b) by A4, FLANG_1:def 1;

        a = x by A3, A8, TARSKI:def 1;

        then b = ( <%> E) by A10, Th4;

        then ( <%> E) in A by A7, A9, FLANG_1: 31;

        then ( <%> E) in (A |^ m) by FLANG_1: 30;

        hence thesis by A2;

      end;

        suppose m < n;

        then

        consider k such that

         A11: (m + k) = n and

         A12: k > 0 by Th3;

        ((A |^ m) ^^ (A |^ k)) = (A |^ n) by A11, FLANG_1: 33;

        then

        consider a, b such that

         A13: a in (A |^ m) and

         A14: b in (A |^ k) and

         A15: x = (a ^ b) by A5, FLANG_1:def 1;

        a = x by A2, A13, TARSKI:def 1;

        then b = ( <%> E) by A15, Th4;

        then ( <%> E) in A by A12, A14, FLANG_1: 31;

        then ( <%> E) in (A |^ m) by FLANG_1: 30;

        hence thesis by A2;

      end;

    end;

    theorem :: FLANG_2:11

    ((A |^ m) |^ n) = ((A |^ n) |^ m)

    proof

      

      thus ((A |^ m) |^ n) = (A |^ (m * n)) by FLANG_1: 34

      .= ((A |^ n) |^ m) by FLANG_1: 34;

    end;

    theorem :: FLANG_2:12

    

     Th12: ((A |^ m) ^^ (A |^ n)) = ((A |^ n) ^^ (A |^ m))

    proof

      

      thus ((A |^ m) ^^ (A |^ n)) = (A |^ (m + n)) by FLANG_1: 33

      .= ((A |^ n) ^^ (A |^ m)) by FLANG_1: 33;

    end;

    theorem :: FLANG_2:13

    ( <%> E) in B implies A c= (A ^^ (B |^ l)) & A c= ((B |^ l) ^^ A)

    proof

      assume ( <%> E) in B;

      then ( <%> E) in (B |^ l) by FLANG_1: 30;

      hence thesis by FLANG_1: 16;

    end;

    theorem :: FLANG_2:14

    A c= (C |^ k) & B c= (C |^ l) implies (A ^^ B) c= (C |^ (k + l))

    proof

      assume A c= (C |^ k) & B c= (C |^ l);

      then (A ^^ B) c= ((C |^ k) ^^ (C |^ l)) by FLANG_1: 17;

      hence thesis by FLANG_1: 33;

    end;

    theorem :: FLANG_2:15

    x in A & x <> ( <%> E) implies (A * ) <> {( <%> E)}

    proof

      assume that

       A1: x in A and

       A2: x <> ( <%> E);

      A <> {( <%> E)} by A1, A2, TARSKI:def 1;

      hence thesis by A1, FLANG_1: 47;

    end;

    theorem :: FLANG_2:16

    

     Th16: ( <%> E) in A & n > 0 implies ((A |^ n) * ) = (A * )

    proof

      assume ( <%> E) in A & n > 0 ;

      then

       A1: (A * ) c= ((A |^ n) * ) by FLANG_1: 35, FLANG_1: 61;

      ((A |^ n) * ) c= (A * ) by FLANG_1: 64;

      hence thesis by A1, XBOOLE_0:def 10;

    end;

    theorem :: FLANG_2:17

    

     Th17: ( <%> E) in A implies ((A |^ n) * ) = ((A * ) |^ n)

    proof

      assume

       A1: ( <%> E) in A;

      per cases ;

        suppose

         A2: n = 0 ;

        

        hence ((A |^ n) * ) = ( {( <%> E)} * ) by FLANG_1: 24

        .= {( <%> E)} by FLANG_1: 47

        .= ((A * ) |^ n) by A2, FLANG_1: 24;

      end;

        suppose

         A3: n > 0 ;

        then ((A * ) |^ n) = (A * ) by FLANG_1: 66;

        hence thesis by A1, A3, Th16;

      end;

    end;

    theorem :: FLANG_2:18

    A c= (A ^^ (B * )) & A c= ((B * ) ^^ A)

    proof

      ( <%> E) in (B * ) by FLANG_1: 48;

      hence thesis by FLANG_1: 16;

    end;

    begin

    definition

      let E, A;

      let m, n;

      :: FLANG_2:def1

      func A |^ (m,n) -> Subset of (E ^omega ) equals ( union { B : ex k st m <= k & k <= n & B = (A |^ k) });

      coherence

      proof

        defpred P[ set] means ex k st m <= k & k <= n & $1 = (A |^ k);

        reconsider M = { B : P[B] } as Subset-Family of (E ^omega ) from DOMAIN_1:sch 7;

        ( union M) is Subset of (E ^omega );

        hence thesis;

      end;

    end

    theorem :: FLANG_2:19

    

     Th19: x in (A |^ (m,n)) iff ex k st m <= k & k <= n & x in (A |^ k)

    proof

      thus x in (A |^ (m,n)) implies ex k st m <= k & k <= n & x in (A |^ k)

      proof

        defpred P[ set] means ex k st m <= k & k <= n & $1 = (A |^ k);

        assume x in (A |^ (m,n));

        then

        consider X such that

         A1: x in X and

         A2: X in { B : ex k st m <= k & k <= n & B = (A |^ k) } by TARSKI:def 4;

        

         A3: X in { B : P[B] } by A2;

         P[X] from CARD_FIL:sch 1( A3);

        hence thesis by A1;

      end;

      given k such that

       A4: m <= k & k <= n & x in (A |^ k);

      defpred P[ set] means ex k st m <= k & k <= n & $1 = (A |^ k);

      consider B such that

       A5: x in B and

       A6: P[B] by A4;

      reconsider A = { C : P[C] } as Subset-Family of (E ^omega ) from DOMAIN_1:sch 7;

      B in A by A6;

      hence thesis by A5, TARSKI:def 4;

    end;

    theorem :: FLANG_2:20

    

     Th20: m <= k & k <= n implies (A |^ k) c= (A |^ (m,n)) by Th19;

    theorem :: FLANG_2:21

    

     Th21: (A |^ (m,n)) = {} iff m > n or m > 0 & A = {}

    proof

       A1:

      now

        assume

         A2: m > 0 & A = {} ;

        now

          let x be object;

          assume x in (A |^ (m,n));

          then ex k st m <= k & k <= n & x in (A |^ k) by Th19;

          hence contradiction by A2, FLANG_1: 27;

        end;

        hence (A |^ (m,n)) = {} by XBOOLE_0:def 1;

      end;

      thus (A |^ (m,n)) = {} implies m > n or m > 0 & A = {}

      proof

        assume that

         A3: (A |^ (m,n)) = {} and

         A4: m <= n & (m <= 0 or A <> {} );

         A5:

        now

          assume that

           A6: m <= n and

           A7: A <> {} ;

          (A |^ m) <> {} by A7, FLANG_1: 27;

          then ex a st a in (A |^ m) by SUBSET_1: 4;

          hence contradiction by A3, A6, Th19;

        end;

        now

          assume that

           A8: m <= n and

           A9: m = 0 ;

           {( <%> E)} = (A |^ m) by A9, FLANG_1: 29;

          then ( <%> E) in (A |^ m) by TARSKI:def 1;

          hence contradiction by A3, A8, Th19;

        end;

        hence thesis by A4, A5;

      end;

      now

        assume

         A10: m > n;

        now

          let x be object;

           not (ex k st m <= k & k <= n & x in (A |^ k)) by A10, XXREAL_0: 2;

          hence not x in (A |^ (m,n)) by Th19;

        end;

        hence (A |^ (m,n)) = {} by XBOOLE_0:def 1;

      end;

      hence thesis by A1;

    end;

    theorem :: FLANG_2:22

    

     Th22: (A |^ (m,m)) = (A |^ m)

    proof

       A1:

      now

        let x be object;

        assume x in (A |^ (m,m));

        then ex k st m <= k & k <= m & x in (A |^ k) by Th19;

        hence x in (A |^ m) by XXREAL_0: 1;

      end;

      for x be object holds x in (A |^ m) implies x in (A |^ (m,m)) by Th19;

      hence thesis by A1, TARSKI: 2;

    end;

    theorem :: FLANG_2:23

    

     Th23: m <= k & l <= n implies (A |^ (k,l)) c= (A |^ (m,n))

    proof

      assume

       A1: m <= k & l <= n;

      thus thesis

      proof

        let x be object;

        assume x in (A |^ (k,l));

        then

        consider kl such that

         A2: k <= kl & kl <= l and

         A3: x in (A |^ kl) by Th19;

        m <= kl & kl <= n by A1, A2, XXREAL_0: 2;

        hence thesis by A3, Th19;

      end;

    end;

    theorem :: FLANG_2:24

    m <= k & k <= n implies (A |^ (m,n)) = ((A |^ (m,k)) \/ (A |^ (k,n)))

    proof

      

       A1: (A |^ (m,n)) c= ((A |^ (m,k)) \/ (A |^ (k,n)))

      proof

        let x be object;

        assume x in (A |^ (m,n));

        then

        consider l such that

         A2: m <= l & l <= n & x in (A |^ l) by Th19;

        l <= k or l > k;

        then x in (A |^ (m,k)) or x in (A |^ (k,n)) by A2, Th19;

        hence thesis by XBOOLE_0:def 3;

      end;

      assume m <= k & k <= n;

      then (A |^ (m,k)) c= (A |^ (m,n)) & (A |^ (k,n)) c= (A |^ (m,n)) by Th23;

      then ((A |^ (m,k)) \/ (A |^ (k,n))) c= (A |^ (m,n)) by XBOOLE_1: 8;

      hence thesis by A1, XBOOLE_0:def 10;

    end;

    theorem :: FLANG_2:25

    

     Th25: m <= k & k <= n implies (A |^ (m,n)) = ((A |^ (m,k)) \/ (A |^ ((k + 1),n)))

    proof

      assume that

       A1: m <= k and

       A2: k <= n;

      per cases ;

        suppose

         A3: k < n;

        m <= (k + 1) by A1, NAT_1: 13;

        then

         A4: (A |^ ((k + 1),n)) c= (A |^ (m,n)) by Th23;

        

         A5: (A |^ (m,n)) c= ((A |^ (m,k)) \/ (A |^ ((k + 1),n)))

        proof

          let x be object;

          assume x in (A |^ (m,n));

          then

          consider mn such that

           A6: m <= mn and

           A7: mn <= n and

           A8: x in (A |^ mn) by Th19;

          

           A9: mn >= (k + 1) implies x in (A |^ ((k + 1),n)) by A7, A8, Th19;

          mn <= k implies x in (A |^ (m,k)) by A6, A8, Th19;

          hence thesis by A9, NAT_1: 13, XBOOLE_0:def 3;

        end;

        (A |^ (m,k)) c= (A |^ (m,n)) by A3, Th23;

        then ((A |^ (m,k)) \/ (A |^ ((k + 1),n))) c= (A |^ (m,n)) by A4, XBOOLE_1: 8;

        hence thesis by A5, XBOOLE_0:def 10;

      end;

        suppose

         A10: k >= n;

        then (k + 1) > (n + 0 ) by XREAL_1: 8;

        then (A |^ ((k + 1),n)) = {} by Th21;

        hence thesis by A2, A10, XXREAL_0: 1;

      end;

    end;

    theorem :: FLANG_2:26

    

     Th26: m <= (n + 1) implies (A |^ (m,(n + 1))) = ((A |^ (m,n)) \/ (A |^ (n + 1)))

    proof

      assume

       A1: m <= (n + 1);

      per cases by A1, NAT_1: 8;

        suppose

         A2: m <= n;

        n < (n + 1) by NAT_1: 13;

        then (A |^ (m,(n + 1))) = ((A |^ (m,n)) \/ (A |^ ((n + 1),(n + 1)))) by A2, Th25;

        hence thesis by Th22;

      end;

        suppose

         A3: m = (n + 1);

        then

         A4: m > n by NAT_1: 13;

        

        thus (A |^ (m,(n + 1))) = ( {} \/ (A |^ (n + 1))) by A3, Th22

        .= ((A |^ (m,n)) \/ (A |^ (n + 1))) by A4, Th21;

      end;

    end;

    theorem :: FLANG_2:27

    m <= n implies (A |^ (m,n)) = ((A |^ m) \/ (A |^ ((m + 1),n)))

    proof

      assume

       A1: m <= n;

      per cases by A1, XXREAL_0: 1;

        suppose m < n;

        then (A |^ (m,n)) = ((A |^ (m,m)) \/ (A |^ ((m + 1),n))) by Th25;

        hence thesis by Th22;

      end;

        suppose

         A2: m = n;

        then

         A3: (m + 1) > n by NAT_1: 13;

        

        thus (A |^ (m,n)) = ((A |^ m) \/ {} ) by A2, Th22

        .= ((A |^ m) \/ (A |^ ((m + 1),n))) by A3, Th21;

      end;

    end;

    theorem :: FLANG_2:28

    

     Th28: (A |^ (n,(n + 1))) = ((A |^ n) \/ (A |^ (n + 1)))

    proof

      

      thus (A |^ (n,(n + 1))) = ((A |^ (n,n)) \/ (A |^ (n + 1))) by Th26, NAT_1: 11

      .= ((A |^ n) \/ (A |^ (n + 1))) by Th22;

    end;

    theorem :: FLANG_2:29

    

     Th29: A c= B implies (A |^ (m,n)) c= (B |^ (m,n))

    proof

      assume

       A1: A c= B;

      thus thesis

      proof

        let x be object;

        assume x in (A |^ (m,n));

        then

        consider k such that

         A2: m <= k & k <= n & x in (A |^ k) by Th19;

        (A |^ k) c= (B |^ k) by A1, FLANG_1: 37;

        hence thesis by A2, Th19;

      end;

    end;

    theorem :: FLANG_2:30

    

     Th30: x in A & x <> ( <%> E) & (m > 0 or n > 0 ) implies (A |^ (m,n)) <> {( <%> E)}

    proof

      assume that

       A1: x in A and

       A2: x <> ( <%> E) and

       A3: m > 0 or n > 0 ;

      per cases by A3;

        suppose m > n;

        hence thesis by Th21;

      end;

        suppose

         A4: m <= n & m > 0 ;

        

         A5: (A |^ m) <> {} by A1, FLANG_1: 27;

        (A |^ m) <> {( <%> E)} by A1, A2, A4, Th7;

        then

         A6: ex x be object st x in (A |^ m) & x <> ( <%> E) by A5, ZFMISC_1: 35;

        (A |^ m) c= (A |^ (m,n)) by A4, Th20;

        hence thesis by A6, TARSKI:def 1;

      end;

        suppose

         A7: m <= n & n > 0 ;

        

         A8: (A |^ n) <> {} by A1, FLANG_1: 27;

        (A |^ n) <> {( <%> E)} by A1, A2, A7, Th7;

        then

         A9: ex x be object st x in (A |^ n) & x <> ( <%> E) by A8, ZFMISC_1: 35;

        (A |^ n) c= (A |^ (m,n)) by A7, Th20;

        hence thesis by A9, TARSKI:def 1;

      end;

    end;

    theorem :: FLANG_2:31

    

     Th31: (A |^ (m,n)) = {( <%> E)} iff m <= n & A = {( <%> E)} or m = 0 & n = 0 or m = 0 & A = {}

    proof

      thus (A |^ (m,n)) = {( <%> E)} implies m <= n & A = {( <%> E)} or m = 0 & n = 0 or m = 0 & A = {}

      proof

        assume that

         A1: (A |^ (m,n)) = {( <%> E)} and

         A2: (m > n or A <> {( <%> E)}) & (m <> 0 or n <> 0 ) & (m <> 0 or A <> {} );

        per cases by A2;

          suppose m > n;

          hence contradiction by A1, Th21;

        end;

          suppose

           A3: m <= n & A <> {( <%> E)} & (m <> 0 or n <> 0 & A <> {} );

          per cases by A3;

            suppose

             A4: m <> 0 ;

            per cases ;

              suppose A = {} ;

              hence contradiction by A1, A4, Th21;

            end;

              suppose A <> {} ;

              then ex x be object st x in A & x <> ( <%> E) by A3, ZFMISC_1: 35;

              hence contradiction by A1, A4, Th30;

            end;

          end;

            suppose

             A5: n <> 0 & A <> {} ;

            then ex x be object st x in A & x <> ( <%> E) by A3, ZFMISC_1: 35;

            hence contradiction by A1, A5, Th30;

          end;

        end;

      end;

      assume

       A6: m <= n & A = {( <%> E)} or m = 0 & n = 0 or m = 0 & A = {} ;

      per cases by A6;

        suppose

         A7: m <= n & A = {( <%> E)};

         A8:

        now

          let x be object;

          assume x in {( <%> E)};

          then

           A9: x in ( {( <%> E)} |^ m) by FLANG_1: 29;

          ( {( <%> E)} |^ m) c= ( {( <%> E)} |^ (m,n)) by A7, Th20;

          hence x in (A |^ (m,n)) by A7, A9;

        end;

        now

          let x be object;

          assume x in (A |^ (m,n));

          then ex k st m <= k & k <= n & x in ( {( <%> E)} |^ k) by A7, Th19;

          hence x in {( <%> E)} by FLANG_1: 29;

        end;

        hence thesis by A8, TARSKI: 2;

      end;

        suppose

         A10: m = 0 & n = 0 ;

        (A |^ ( 0 , 0 )) = (A |^ 0 ) by Th22

        .= {( <%> E)} by FLANG_1: 29;

        hence thesis by A10;

      end;

        suppose

         A11: m = 0 & A = {} ;

        now

          let x be object;

          assume x in (A |^ (1,n));

          then ex k st 1 <= k & k <= n & x in (A |^ k) by Th19;

          hence contradiction by A11, FLANG_1: 27;

        end;

        then

         A12: (A |^ (1,n)) = {} by XBOOLE_0:def 1;

        (A |^ ( 0 ,n)) = ((A |^ ( 0 , 0 )) \/ (A |^ (( 0 + 1),n))) by Th25

        .= ((A |^ 0 ) \/ (A |^ (( 0 + 1),n))) by Th22

        .= {( <%> E)} by A12, FLANG_1: 29;

        hence thesis by A11;

      end;

    end;

    theorem :: FLANG_2:32

    

     Th32: (A |^ (m,n)) c= (A * )

    proof

      let x be object;

      assume x in (A |^ (m,n));

      then ex k st m <= k & k <= n & x in (A |^ k) by Th19;

      hence thesis by FLANG_1: 41;

    end;

    theorem :: FLANG_2:33

    

     Th33: ( <%> E) in (A |^ (m,n)) iff m = 0 or m <= n & ( <%> E) in A

    proof

      thus ( <%> E) in (A |^ (m,n)) implies m = 0 or m <= n & ( <%> E) in A

      proof

        assume that

         A1: ( <%> E) in (A |^ (m,n)) and

         A2: m <> 0 & (m > n or not ( <%> E) in A);

        per cases by A2;

          suppose m <> 0 & m > n;

          hence contradiction by A1, Th21;

        end;

          suppose

           A3: m <> 0 & not ( <%> E) in A;

          consider k such that

           A4: m <= k and k <= n and

           A5: ( <%> E) in (A |^ k) by A1, Th19;

          k > 0 by A3, A4;

          hence contradiction by A3, A5, FLANG_1: 31;

        end;

      end;

      assume

       A6: m = 0 or m <= n & ( <%> E) in A;

      per cases by A6;

        suppose

         A7: m = 0 ;

         {( <%> E)} = (A |^ 0 ) by FLANG_1: 29;

        then

         A8: {( <%> E)} c= (A |^ ( 0 ,n)) by Th20;

        ( <%> E) in {( <%> E)} by TARSKI:def 1;

        hence thesis by A7, A8;

      end;

        suppose m <= n & ( <%> E) in A;

        then ( <%> E) in (A |^ m) & (A |^ m) c= (A |^ (m,n)) by Th20, FLANG_1: 30;

        hence thesis;

      end;

    end;

    theorem :: FLANG_2:34

    

     Th34: ( <%> E) in A & m <= n implies (A |^ (m,n)) = (A |^ n)

    proof

      assume that

       A1: ( <%> E) in A and

       A2: m <= n;

      

       A3: (A |^ (m,n)) c= (A |^ n)

      proof

         A4:

        now

          let k such that

           A5: k <= n;

          per cases by A5, XXREAL_0: 1;

            suppose k < n;

            hence (A |^ k) c= (A |^ n) by A1, FLANG_1: 36;

          end;

            suppose k = n;

            hence (A |^ k) c= (A |^ n);

          end;

        end;

        let x be object;

        assume x in (A |^ (m,n));

        then

        consider k such that m <= k and

         A6: k <= n and

         A7: x in (A |^ k) by Th19;

        (A |^ k) c= (A |^ n) by A4, A6;

        hence thesis by A7;

      end;

      (A |^ n) c= (A |^ (m,n)) by A2, Th20;

      hence thesis by A3, XBOOLE_0:def 10;

    end;

    theorem :: FLANG_2:35

    

     Th35: ((A |^ (m,n)) ^^ (A |^ k)) = ((A |^ k) ^^ (A |^ (m,n)))

    proof

       A1:

      now

        let x be object;

        assume x in ((A |^ k) ^^ (A |^ (m,n)));

        then

        consider a, b such that

         A2: a in (A |^ k) and

         A3: b in (A |^ (m,n)) and

         A4: x = (a ^ b) by FLANG_1:def 1;

        consider mn such that

         A5: m <= mn & mn <= n and

         A6: b in (A |^ mn) by A3, Th19;

        (A |^ mn) c= (A |^ (m,n)) by A5, Th20;

        then

         A7: ((A |^ mn) ^^ (A |^ k)) c= ((A |^ (m,n)) ^^ (A |^ k)) by FLANG_1: 17;

        (a ^ b) in ((A |^ k) ^^ (A |^ mn)) by A2, A6, FLANG_1:def 1;

        then (a ^ b) in ((A |^ mn) ^^ (A |^ k)) by Th12;

        hence x in ((A |^ (m,n)) ^^ (A |^ k)) by A4, A7;

      end;

      now

        let x be object;

        assume x in ((A |^ (m,n)) ^^ (A |^ k));

        then

        consider a, b such that

         A8: a in (A |^ (m,n)) and

         A9: b in (A |^ k) and

         A10: x = (a ^ b) by FLANG_1:def 1;

        consider mn such that

         A11: m <= mn & mn <= n and

         A12: a in (A |^ mn) by A8, Th19;

        (A |^ mn) c= (A |^ (m,n)) by A11, Th20;

        then

         A13: ((A |^ k) ^^ (A |^ mn)) c= ((A |^ k) ^^ (A |^ (m,n))) by FLANG_1: 17;

        (a ^ b) in ((A |^ mn) ^^ (A |^ k)) by A9, A12, FLANG_1:def 1;

        then (a ^ b) in ((A |^ k) ^^ (A |^ mn)) by Th12;

        hence x in ((A |^ k) ^^ (A |^ (m,n))) by A10, A13;

      end;

      hence thesis by A1, TARSKI: 2;

    end;

    theorem :: FLANG_2:36

    

     Th36: ((A |^ (m,n)) ^^ A) = (A ^^ (A |^ (m,n)))

    proof

      

      thus ((A |^ (m,n)) ^^ A) = ((A |^ (m,n)) ^^ (A |^ 1)) by FLANG_1: 25

      .= ((A |^ 1) ^^ (A |^ (m,n))) by Th35

      .= (A ^^ (A |^ (m,n))) by FLANG_1: 25;

    end;

    theorem :: FLANG_2:37

    

     Th37: m <= n & k <= l implies ((A |^ (m,n)) ^^ (A |^ (k,l))) = (A |^ ((m + k),(n + l)))

    proof

      assume

       A1: m <= n & k <= l;

       A2:

      now

        let x be object;

        assume x in (A |^ ((m + k),(n + l)));

        then

        consider i such that

         A3: (m + k) <= i & i <= (n + l) and

         A4: x in (A |^ i) by Th19;

        consider mn, kl such that

         A5: (mn + kl) = i and

         A6: m <= mn & mn <= n & k <= kl & kl <= l by A1, A3, Th2;

        (A |^ mn) c= (A |^ (m,n)) & (A |^ kl) c= (A |^ (k,l)) by A6, Th20;

        then ((A |^ mn) ^^ (A |^ kl)) c= ((A |^ (m,n)) ^^ (A |^ (k,l))) by FLANG_1: 17;

        then (A |^ (mn + kl)) c= ((A |^ (m,n)) ^^ (A |^ (k,l))) by FLANG_1: 33;

        hence x in ((A |^ (m,n)) ^^ (A |^ (k,l))) by A4, A5;

      end;

      now

        let x be object;

        assume x in ((A |^ (m,n)) ^^ (A |^ (k,l)));

        then

        consider a, b such that

         A7: a in (A |^ (m,n)) and

         A8: b in (A |^ (k,l)) and

         A9: x = (a ^ b) by FLANG_1:def 1;

        consider kl such that

         A10: k <= kl and

         A11: kl <= l and

         A12: b in (A |^ kl) by A8, Th19;

        consider mn such that

         A13: m <= mn and

         A14: mn <= n and

         A15: a in (A |^ mn) by A7, Th19;

        

         A16: (mn + kl) <= (n + l) by A14, A11, XREAL_1: 7;

        (a ^ b) in (A |^ (mn + kl)) & (m + k) <= (mn + kl) by A13, A15, A10, A12, FLANG_1: 40, XREAL_1: 7;

        hence x in (A |^ ((m + k),(n + l))) by A9, A16, Th19;

      end;

      hence thesis by A2, TARSKI: 2;

    end;

    theorem :: FLANG_2:38

    

     Th38: (A |^ ((m + 1),(n + 1))) = ((A |^ (m,n)) ^^ A)

    proof

      per cases ;

        suppose m <= n;

        

        hence (A |^ ((m + 1),(n + 1))) = ((A |^ (m,n)) ^^ (A |^ (1,1))) by Th37

        .= ((A |^ (m,n)) ^^ (A |^ 1)) by Th22

        .= ((A |^ (m,n)) ^^ A) by FLANG_1: 25;

      end;

        suppose

         A1: m > n;

        then (A |^ (m,n)) = {} by Th21;

        then

         A2: ((A |^ (m,n)) ^^ A) = {} by FLANG_1: 12;

        (m + 1) > (n + 1) by A1, XREAL_1: 8;

        hence thesis by A2, Th21;

      end;

    end;

    theorem :: FLANG_2:39

    

     Th39: ((A |^ (m,n)) ^^ (A |^ (k,l))) = ((A |^ (k,l)) ^^ (A |^ (m,n)))

    proof

      per cases ;

        suppose

         A1: m <= n & k <= l;

        

        hence ((A |^ (m,n)) ^^ (A |^ (k,l))) = (A |^ ((m + k),(n + l))) by Th37

        .= ((A |^ (k,l)) ^^ (A |^ (m,n))) by A1, Th37;

      end;

        suppose m > n;

        then

         A2: (A |^ (m,n)) = {} by Th21;

        then ((A |^ (m,n)) ^^ (A |^ (k,l))) = {} by FLANG_1: 12;

        hence thesis by A2, FLANG_1: 12;

      end;

        suppose k > l;

        then

         A3: (A |^ (k,l)) = {} by Th21;

        then ((A |^ (m,n)) ^^ (A |^ (k,l))) = {} by FLANG_1: 12;

        hence thesis by A3, FLANG_1: 12;

      end;

    end;

    theorem :: FLANG_2:40

    

     Th40: ((A |^ (m,n)) |^ k) = (A |^ ((m * k),(n * k)))

    proof

      per cases ;

        suppose

         A1: m <= n;

        defpred P[ Nat] means ((A |^ (m,n)) |^ $1) = (A |^ ((m * $1),(n * $1)));

         A2:

        now

          let k;

          

           A3: (m * k) <= (n * k) by A1, XREAL_1: 64;

          assume P[k];

          

          then ((A |^ (m,n)) |^ (k + 1)) = ((A |^ ((m * k),(n * k))) ^^ (A |^ (m,n))) by FLANG_1: 23

          .= (A |^ (((m * k) + m),((n * k) + n))) by A1, A3, Th37

          .= (A |^ ((m * (k + 1)),(n * (k + 1))));

          hence P[(k + 1)];

        end;

        ((A |^ (m,n)) |^ 0 ) = {( <%> E)} by FLANG_1: 24

        .= (A |^ 0 ) by FLANG_1: 24

        .= (A |^ ((m * 0 ),(n * 0 ))) by Th22;

        then

         A4: P[ 0 ];

        for k holds P[k] from NAT_1:sch 2( A4, A2);

        hence thesis;

      end;

        suppose

         A5: k = 0 ;

        

        hence ((A |^ (m,n)) |^ k) = {( <%> E)} by FLANG_1: 24

        .= (A |^ 0 ) by FLANG_1: 24

        .= (A |^ ((m * k),(n * k))) by A5, Th22;

      end;

        suppose

         A6: m > n & k <> 0 ;

        then (A |^ (m,n)) = {} by Th21;

        then

         A7: ((A |^ (m,n)) |^ k) = {} by A6, FLANG_1: 27;

        (m * k) > (n * k) by A6, XREAL_1: 68;

        hence thesis by A7, Th21;

      end;

    end;

    theorem :: FLANG_2:41

    

     Th41: ((A |^ (k + 1)) |^ (m,n)) c= (((A |^ k) |^ (m,n)) ^^ (A |^ (m,n)))

    proof

      let x be object;

      assume x in ((A |^ (k + 1)) |^ (m,n));

      then

      consider mn such that

       A1: m <= mn & mn <= n and

       A2: x in ((A |^ (k + 1)) |^ mn) by Th19;

      (A |^ mn) c= (A |^ (m,n)) by A1, Th20;

      then

       A3: (((A |^ k) |^ (m,n)) ^^ (A |^ mn)) c= (((A |^ k) |^ (m,n)) ^^ (A |^ (m,n))) by FLANG_1: 17;

      x in (A |^ ((k + 1) * mn)) by A2, FLANG_1: 34;

      then x in (A |^ ((k * mn) + mn));

      then x in ((A |^ (k * mn)) ^^ (A |^ mn)) by FLANG_1: 33;

      then

       A4: x in (((A |^ k) |^ mn) ^^ (A |^ mn)) by FLANG_1: 34;

      ((A |^ k) |^ mn) c= ((A |^ k) |^ (m,n)) by A1, Th20;

      then (((A |^ k) |^ mn) ^^ (A |^ mn)) c= (((A |^ k) |^ (m,n)) ^^ (A |^ mn)) by FLANG_1: 17;

      then x in (((A |^ k) |^ (m,n)) ^^ (A |^ mn)) by A4;

      hence thesis by A3;

    end;

    theorem :: FLANG_2:42

    

     Th42: ((A |^ k) |^ (m,n)) c= (A |^ ((k * m),(k * n)))

    proof

      per cases ;

        suppose

         A1: m <= n;

        defpred P[ Nat] means ((A |^ $1) |^ (m,n)) c= (A |^ (($1 * m),($1 * n)));

         A2:

        now

          let l;

          

           A3: (l * m) <= (l * n) by A1, XREAL_1: 64;

          assume P[l];

          then

           A4: (((A |^ l) |^ (m,n)) ^^ ((A |^ 1) |^ (m,n))) c= ((A |^ ((l * m),(l * n))) ^^ ((A |^ 1) |^ (m,n))) by FLANG_1: 17;

          ((A |^ (l + 1)) |^ (m,n)) c= (((A |^ l) |^ (m,n)) ^^ (A |^ (m,n))) by Th41;

          then

           A5: ((A |^ (l + 1)) |^ (m,n)) c= (((A |^ l) |^ (m,n)) ^^ ((A |^ 1) |^ (m,n))) by FLANG_1: 25;

          ((A |^ ((l * m),(l * n))) ^^ ((A |^ 1) |^ (m,n))) = ((A |^ ((l * m),(l * n))) ^^ (A |^ (m,n))) by FLANG_1: 25

          .= (A |^ (((l * m) + m),((l * n) + n))) by A1, A3, Th37

          .= (A |^ (((l + 1) * m),((l + 1) * n)));

          hence P[(l + 1)] by A5, A4, XBOOLE_1: 1;

        end;

        ((A |^ 0 ) |^ (m,n)) = ( {( <%> E)} |^ (m,n)) by FLANG_1: 24

        .= {( <%> E)} by A1, Th31

        .= (A |^ 0 ) by FLANG_1: 24

        .= (A |^ (( 0 * m),( 0 * n))) by Th22;

        then

         A6: P[ 0 ];

        for l holds P[l] from NAT_1:sch 2( A6, A2);

        hence thesis;

      end;

        suppose m > n;

        then ((A |^ k) |^ (m,n)) = {} by Th21;

        hence thesis;

      end;

    end;

    theorem :: FLANG_2:43

    ((A |^ k) |^ (m,n)) c= ((A |^ (m,n)) |^ k)

    proof

      ((A |^ (m,n)) |^ k) = (A |^ ((m * k),(n * k))) by Th40;

      hence thesis by Th42;

    end;

    theorem :: FLANG_2:44

    ((A |^ (k + l)) |^ (m,n)) c= (((A |^ k) |^ (m,n)) ^^ ((A |^ l) |^ (m,n)))

    proof

      let x be object;

      assume x in ((A |^ (k + l)) |^ (m,n));

      then

      consider mn such that

       A1: m <= mn & mn <= n and

       A2: x in ((A |^ (k + l)) |^ mn) by Th19;

      x in (A |^ ((k + l) * mn)) by A2, FLANG_1: 34;

      then x in (A |^ ((k * mn) + (l * mn)));

      then x in ((A |^ (k * mn)) ^^ (A |^ (l * mn))) by FLANG_1: 33;

      then

      consider a, b such that

       A3: a in (A |^ (k * mn)) and

       A4: b in (A |^ (l * mn)) and

       A5: x = (a ^ b) by FLANG_1:def 1;

      b in ((A |^ l) |^ mn) by A4, FLANG_1: 34;

      then

       A6: b in ((A |^ l) |^ (m,n)) by A1, Th19;

      a in ((A |^ k) |^ mn) by A3, FLANG_1: 34;

      then a in ((A |^ k) |^ (m,n)) by A1, Th19;

      hence thesis by A5, A6, FLANG_1:def 1;

    end;

    theorem :: FLANG_2:45

    

     Th45: (A |^ ( 0 , 0 )) = {( <%> E)}

    proof

      

      thus (A |^ ( 0 , 0 )) = (A |^ 0 ) by Th22

      .= {( <%> E)} by FLANG_1: 24;

    end;

    theorem :: FLANG_2:46

    

     Th46: (A |^ ( 0 ,1)) = ( {( <%> E)} \/ A)

    proof

      

      thus (A |^ ( 0 ,1)) = ((A |^ 0 ) \/ (A |^ ( 0 + 1))) by Th28

      .= ( {( <%> E)} \/ (A |^ 1)) by FLANG_1: 24

      .= ( {( <%> E)} \/ A) by FLANG_1: 25;

    end;

    theorem :: FLANG_2:47

    (A |^ (1,1)) = A

    proof

      

      thus (A |^ (1,1)) = (A |^ 1) by Th22

      .= A by FLANG_1: 25;

    end;

    theorem :: FLANG_2:48

    (A |^ ( 0 ,2)) = (( {( <%> E)} \/ A) \/ (A ^^ A))

    proof

      

      thus (A |^ ( 0 ,2)) = ((A |^ ( 0 ,1)) \/ (A |^ (1 + 1))) by Th26

      .= (( {( <%> E)} \/ A) \/ (A |^ (1 + 1))) by Th46

      .= (( {( <%> E)} \/ A) \/ (A ^^ A)) by FLANG_1: 26;

    end;

    theorem :: FLANG_2:49

    (A |^ (1,2)) = (A \/ (A ^^ A))

    proof

      

      thus (A |^ (1,2)) = ((A |^ 1) \/ (A |^ (1 + 1))) by Th28

      .= (A \/ (A |^ 2)) by FLANG_1: 25

      .= (A \/ (A ^^ A)) by FLANG_1: 26;

    end;

    theorem :: FLANG_2:50

    (A |^ (2,2)) = (A ^^ A)

    proof

      

      thus (A |^ (2,2)) = (A |^ 2) by Th22

      .= (A ^^ A) by FLANG_1: 26;

    end;

    theorem :: FLANG_2:51

    

     Th51: m > 0 & (A |^ (m,n)) = {x} implies for mn st m <= mn & mn <= n holds (A |^ mn) = {x}

    proof

      assume that

       A1: m > 0 and

       A2: (A |^ (m,n)) = {x};

      given mn such that

       A3: m <= mn & mn <= n and

       A4: (A |^ mn) <> {x};

      per cases ;

        suppose

         A5: (A |^ mn) = {} ;

        x in (A |^ (m,n)) by A2, TARSKI:def 1;

        then

         A6: ex i st m <= i & i <= n & x in (A |^ i) by Th19;

        A = {} by A5, FLANG_1: 27;

        hence contradiction by A1, A6, FLANG_1: 27;

      end;

        suppose (A |^ mn) <> {} ;

        then

        consider y be object such that

         A7: y in (A |^ mn) and

         A8: y <> x by A4, ZFMISC_1: 35;

        y in (A |^ (m,n)) by A3, A7, Th19;

        hence contradiction by A2, A8, TARSKI:def 1;

      end;

    end;

    theorem :: FLANG_2:52

    

     Th52: m <> n & (A |^ (m,n)) = {x} implies x = ( <%> E)

    proof

      assume that

       A1: m <> n and

       A2: (A |^ (m,n)) = {x};

      per cases ;

        suppose m > n;

        hence thesis by A2, Th21;

      end;

        suppose

         A3: m = 0 & m <= n;

        then {( <%> E)} = (A |^ m) by FLANG_1: 24;

        then ( <%> E) in (A |^ m) by TARSKI:def 1;

        then ( <%> E) in (A |^ (m,n)) by A3, Th19;

        hence thesis by A2;

      end;

        suppose m > 0 & m <= n;

        then (A |^ m) = {x} & (A |^ n) = {x} by A2, Th51;

        hence thesis by A1, Th10;

      end;

    end;

    theorem :: FLANG_2:53

    

     Th53: <%x%> in (A |^ (m,n)) iff <%x%> in A & m <= n & (( <%> E) in A & n > 0 or m <= 1 & 1 <= n)

    proof

      thus <%x%> in (A |^ (m,n)) implies <%x%> in A & m <= n & (( <%> E) in A & n > 0 or m <= 1 & 1 <= n)

      proof

        assume

         A1: <%x%> in (A |^ (m,n));

        then ex mn st m <= mn & mn <= n & <%x%> in (A |^ mn) by Th19;

        hence thesis by A1, Th9, Th21;

      end;

      assume that

       A2: <%x%> in A and

       A3: m <= n and

       A4: ( <%> E) in A & n > 0 or m <= 1 & 1 <= n;

      per cases by A4;

        suppose ( <%> E) in A & n > 0 ;

        then A c= (A |^ n) by FLANG_1: 35;

        hence thesis by A2, A3, Th19;

      end;

        suppose

         A5: m <= 1 & 1 <= n;

         <%x%> in (A |^ 1) by A2, FLANG_1: 25;

        hence thesis by A5, Th19;

      end;

    end;

    theorem :: FLANG_2:54

    ((A /\ B) |^ (m,n)) c= ((A |^ (m,n)) /\ (B |^ (m,n)))

    proof

      let x be object;

      assume x in ((A /\ B) |^ (m,n));

      then

      consider mn such that

       A1: m <= mn & mn <= n and

       A2: x in ((A /\ B) |^ mn) by Th19;

      

       A3: ((A /\ B) |^ mn) c= ((A |^ mn) /\ (B |^ mn)) by FLANG_1: 39;

      then x in (B |^ mn) by A2, XBOOLE_0:def 4;

      then

       A4: x in (B |^ (m,n)) by A1, Th19;

      x in (A |^ mn) by A2, A3, XBOOLE_0:def 4;

      then x in (A |^ (m,n)) by A1, Th19;

      hence thesis by A4, XBOOLE_0:def 4;

    end;

    theorem :: FLANG_2:55

    ((A |^ (m,n)) \/ (B |^ (m,n))) c= ((A \/ B) |^ (m,n))

    proof

      let x be object;

      assume

       A1: x in ((A |^ (m,n)) \/ (B |^ (m,n)));

      per cases by A1, XBOOLE_0:def 3;

        suppose x in (A |^ (m,n));

        then

        consider mn such that

         A2: m <= mn & mn <= n and

         A3: x in (A |^ mn) by Th19;

        

         A4: ((A |^ mn) \/ (B |^ mn)) c= ((A \/ B) |^ mn) by FLANG_1: 38;

        x in ((A |^ mn) \/ (B |^ mn)) by A3, XBOOLE_0:def 3;

        hence thesis by A2, A4, Th19;

      end;

        suppose x in (B |^ (m,n));

        then

        consider mn such that

         A5: m <= mn & mn <= n and

         A6: x in (B |^ mn) by Th19;

        

         A7: ((A |^ mn) \/ (B |^ mn)) c= ((A \/ B) |^ mn) by FLANG_1: 38;

        x in ((A |^ mn) \/ (B |^ mn)) by A6, XBOOLE_0:def 3;

        hence thesis by A5, A7, Th19;

      end;

    end;

    theorem :: FLANG_2:56

    ((A |^ (m,n)) |^ (k,l)) c= (A |^ ((m * k),(n * l)))

    proof

      let x be object;

      assume x in ((A |^ (m,n)) |^ (k,l));

      then

      consider kl such that

       A1: k <= kl & kl <= l and

       A2: x in ((A |^ (m,n)) |^ kl) by Th19;

      (m * k) <= (m * kl) & (n * kl) <= (n * l) by A1, NAT_1: 4;

      then

       A3: (A |^ ((m * kl),(n * kl))) c= (A |^ ((m * k),(n * l))) by Th23;

      x in (A |^ ((m * kl),(n * kl))) by A2, Th40;

      hence thesis by A3;

    end;

    theorem :: FLANG_2:57

    m <= n & ( <%> E) in B implies A c= (A ^^ (B |^ (m,n))) & A c= ((B |^ (m,n)) ^^ A)

    proof

      assume m <= n & ( <%> E) in B;

      then ( <%> E) in (B |^ (m,n)) by Th33;

      hence thesis by FLANG_1: 16;

    end;

    theorem :: FLANG_2:58

    m <= n & k <= l & A c= (C |^ (m,n)) & B c= (C |^ (k,l)) implies (A ^^ B) c= (C |^ ((m + k),(n + l)))

    proof

      assume that

       A1: m <= n & k <= l and

       A2: A c= (C |^ (m,n)) & B c= (C |^ (k,l));

      thus thesis

      proof

        let x be object;

        assume x in (A ^^ B);

        then

        consider a, b such that

         A3: a in A & b in B and

         A4: x = (a ^ b) by FLANG_1:def 1;

        (a ^ b) in ((C |^ (m,n)) ^^ (C |^ (k,l))) by A2, A3, FLANG_1:def 1;

        hence thesis by A1, A4, Th37;

      end;

    end;

    theorem :: FLANG_2:59

    ((A |^ (m,n)) * ) c= (A * )

    proof

      let x be object;

      assume x in ((A |^ (m,n)) * );

      then

      consider k such that

       A1: x in ((A |^ (m,n)) |^ k) by FLANG_1: 41;

      ((A |^ (m,n)) |^ k) = (A |^ ((m * k),(n * k))) & (A |^ ((m * k),(n * k))) c= (A * ) by Th32, Th40;

      hence thesis by A1;

    end;

    theorem :: FLANG_2:60

    ((A * ) |^ (m,n)) c= (A * )

    proof

      let x be object;

      assume x in ((A * ) |^ (m,n));

      then

      consider mn such that m <= mn and mn <= n and

       A1: x in ((A * ) |^ mn) by Th19;

      ((A * ) |^ mn) c= (A * ) by FLANG_1: 65;

      hence thesis by A1;

    end;

    theorem :: FLANG_2:61

    m <= n & n > 0 implies ((A * ) |^ (m,n)) = (A * )

    proof

      assume that

       A1: m <= n and

       A2: n > 0 ;

      ( <%> E) in (A * ) by FLANG_1: 48;

      

      hence ((A * ) |^ (m,n)) = ((A * ) |^ n) by A1, Th34

      .= (A * ) by A2, FLANG_1: 66;

    end;

    theorem :: FLANG_2:62

    m <= n & n > 0 & ( <%> E) in A implies ((A |^ (m,n)) * ) = (A * )

    proof

      assume that

       A1: m <= n and

       A2: n > 0 and

       A3: ( <%> E) in A;

      

      thus ((A |^ (m,n)) * ) = ((A |^ n) * ) by A1, A3, Th34

      .= (A * ) by A2, A3, Th16;

    end;

    theorem :: FLANG_2:63

    m <= n & ( <%> E) in A implies ((A |^ (m,n)) * ) = ((A * ) |^ (m,n))

    proof

      assume that

       A1: m <= n and

       A2: ( <%> E) in A;

      ((A |^ (m,n)) * ) = ((A |^ n) * ) & ((A * ) |^ (m,n)) = ((A * ) |^ n) by A1, A2, Th34, FLANG_1: 48;

      hence thesis by A2, Th17;

    end;

    theorem :: FLANG_2:64

    

     Th64: A c= (B * ) implies (A |^ (m,n)) c= (B * )

    proof

      assume

       A1: A c= (B * );

      thus thesis

      proof

        let x be object;

        assume x in (A |^ (m,n));

        then

        consider mn such that m <= mn and mn <= n and

         A2: x in (A |^ mn) by Th19;

        (A |^ mn) c= (B * ) by A1, FLANG_1: 59;

        hence thesis by A2;

      end;

    end;

    theorem :: FLANG_2:65

    A c= (B * ) implies (B * ) = ((B \/ (A |^ (m,n))) * ) by Th64, FLANG_1: 67;

    theorem :: FLANG_2:66

    

     Th66: ((A |^ (m,n)) ^^ (A * )) = ((A * ) ^^ (A |^ (m,n)))

    proof

      

       A1: ((A * ) ^^ (A |^ (m,n))) c= ((A |^ (m,n)) ^^ (A * ))

      proof

        let x be object;

        assume x in ((A * ) ^^ (A |^ (m,n)));

        then

        consider a, b such that

         A2: a in (A * ) and

         A3: b in (A |^ (m,n)) and

         A4: x = (a ^ b) by FLANG_1:def 1;

        consider k such that

         A5: a in (A |^ k) by A2, FLANG_1: 41;

        consider mn such that

         A6: m <= mn & mn <= n and

         A7: b in (A |^ mn) by A3, Th19;

        (A |^ k) c= (A * ) & (A |^ mn) c= (A |^ (m,n)) by A6, Th20, FLANG_1: 42;

        then

         A8: ((A |^ mn) ^^ (A |^ k)) c= ((A |^ (m,n)) ^^ (A * )) by FLANG_1: 17;

        (a ^ b) in (A |^ (mn + k)) by A7, A5, FLANG_1: 40;

        then (a ^ b) in ((A |^ mn) ^^ (A |^ k)) by FLANG_1: 33;

        hence thesis by A4, A8;

      end;

      ((A |^ (m,n)) ^^ (A * )) c= ((A * ) ^^ (A |^ (m,n)))

      proof

        let x be object;

        assume x in ((A |^ (m,n)) ^^ (A * ));

        then

        consider a, b such that

         A9: a in (A |^ (m,n)) and

         A10: b in (A * ) and

         A11: x = (a ^ b) by FLANG_1:def 1;

        consider k such that

         A12: b in (A |^ k) by A10, FLANG_1: 41;

        consider mn such that

         A13: m <= mn & mn <= n and

         A14: a in (A |^ mn) by A9, Th19;

        (A |^ k) c= (A * ) & (A |^ mn) c= (A |^ (m,n)) by A13, Th20, FLANG_1: 42;

        then

         A15: ((A |^ k) ^^ (A |^ mn)) c= ((A * ) ^^ (A |^ (m,n))) by FLANG_1: 17;

        (a ^ b) in (A |^ (k + mn)) by A14, A12, FLANG_1: 40;

        then (a ^ b) in ((A |^ k) ^^ (A |^ mn)) by FLANG_1: 33;

        hence thesis by A11, A15;

      end;

      hence thesis by A1, XBOOLE_0:def 10;

    end;

    theorem :: FLANG_2:67

    ( <%> E) in A & m <= n implies (A * ) = ((A * ) ^^ (A |^ (m,n)))

    proof

      assume that

       A1: ( <%> E) in A and

       A2: m <= n;

      

       A3: ex k st (m + k) = n by A2, NAT_1: 10;

      defpred P[ Nat] means (A * ) = ((A * ) ^^ (A |^ (m,(m + $1))));

       A4:

      now

        let i;

        assume

         A5: P[i];

        (A |^ (m,(m + (i + 1)))) = ((A |^ (m,(m + i))) \/ (A |^ ((m + i) + 1))) by Th26, NAT_1: 11;

        

        then ((A * ) ^^ (A |^ (m,(m + (i + 1))))) = ((A * ) \/ ((A * ) ^^ (A |^ ((m + i) + 1)))) by A5, FLANG_1: 20

        .= ((A * ) \/ (A * )) by A1, FLANG_1: 55;

        hence P[(i + 1)];

      end;

      (A * ) = ((A * ) ^^ (A |^ m)) by A1, FLANG_1: 55

      .= ((A * ) ^^ (A |^ (m,(m + 0 )))) by Th22;

      then

       A6: P[ 0 ];

      for i holds P[i] from NAT_1:sch 2( A6, A4);

      hence thesis by A3;

    end;

    theorem :: FLANG_2:68

    ((A |^ (m,n)) |^ k) c= (A * ) by Th32, FLANG_1: 59;

    theorem :: FLANG_2:69

    

     Th69: ((A |^ k) |^ (m,n)) c= (A * )

    proof

      let x be object;

      assume x in ((A |^ k) |^ (m,n));

      then

      consider mn such that m <= mn and mn <= n and

       A1: x in ((A |^ k) |^ mn) by Th19;

      

       A2: (A |^ (k * mn)) c= (A * ) by FLANG_1: 42;

      x in (A |^ (k * mn)) by A1, FLANG_1: 34;

      hence thesis by A2;

    end;

    theorem :: FLANG_2:70

    m <= n implies ((A |^ m) * ) c= ((A |^ (m,n)) * ) by Th20, FLANG_1: 61;

    theorem :: FLANG_2:71

    

     Th71: ((A |^ (m,n)) |^ (k,l)) c= (A * )

    proof

      let x be object;

      assume x in ((A |^ (m,n)) |^ (k,l));

      then

      consider kl such that k <= kl and kl <= l and

       A1: x in ((A |^ (m,n)) |^ kl) by Th19;

      ((A |^ (m,n)) |^ kl) c= (A * ) by Th32, FLANG_1: 59;

      hence thesis by A1;

    end;

    theorem :: FLANG_2:72

    

     Th72: ( <%> E) in A & k <= n & l <= n implies (A |^ (k,n)) = (A |^ (l,n))

    proof

      assume that

       A1: ( <%> E) in A and

       A2: k <= n and

       A3: l <= n;

      

      thus (A |^ (k,n)) = (A |^ n) by A1, A2, Th34

      .= (A |^ (l,n)) by A1, A3, Th34;

    end;

    begin

    definition

      let E, A;

      :: FLANG_2:def2

      func A ? -> Subset of (E ^omega ) equals ( union { B : ex k st k <= 1 & B = (A |^ k) });

      coherence

      proof

        defpred P[ set] means ex k st k <= 1 & $1 = (A |^ k);

        reconsider M = { B : P[B] } as Subset-Family of (E ^omega ) from DOMAIN_1:sch 7;

        ( union M) is Subset of (E ^omega );

        hence thesis;

      end;

    end

    theorem :: FLANG_2:73

    

     Th73: x in (A ? ) iff ex k st k <= 1 & x in (A |^ k)

    proof

      thus x in (A ? ) implies ex k st k <= 1 & x in (A |^ k)

      proof

        defpred P[ set] means ex k st k <= 1 & $1 = (A |^ k);

        assume x in (A ? );

        then

        consider X such that

         A1: x in X and

         A2: X in { B : ex k st k <= 1 & B = (A |^ k) } by TARSKI:def 4;

        

         A3: X in { B : P[B] } by A2;

         P[X] from CARD_FIL:sch 1( A3);

        hence thesis by A1;

      end;

      given k such that

       A4: k <= 1 & x in (A |^ k);

      defpred P[ set] means ex k st k <= 1 & $1 = (A |^ k);

      consider B such that

       A5: x in B and

       A6: P[B] by A4;

      reconsider A = { C : P[C] } as Subset-Family of (E ^omega ) from DOMAIN_1:sch 7;

      B in A by A6;

      hence thesis by A5, TARSKI:def 4;

    end;

    theorem :: FLANG_2:74

    n <= 1 implies (A |^ n) c= (A ? ) by Th73;

    theorem :: FLANG_2:75

    

     Th75: (A ? ) = ((A |^ 0 ) \/ (A |^ 1))

    proof

      now

        let x be object;

        x in (A ? ) iff ex k st (k = 0 or k = 1) & x in (A |^ k)

        proof

          thus x in (A ? ) implies ex k st (k = 0 or k = 1) & x in (A |^ k)

          proof

            assume x in (A ? );

            then

            consider k such that

             A1: k <= 1 and

             A2: x in (A |^ k) by Th73;

            k = 0 or k = 1 by A1, NAT_1: 25;

            hence thesis by A2;

          end;

          given k such that

           A3: (k = 0 or k = 1) & x in (A |^ k);

          thus thesis by A3, Th73;

        end;

        hence x in (A ? ) iff x in (A |^ 0 ) or x in (A |^ 1);

      end;

      hence thesis by XBOOLE_0:def 3;

    end;

    theorem :: FLANG_2:76

    

     Th76: (A ? ) = ( {( <%> E)} \/ A)

    proof

      (A |^ 0 ) = {( <%> E)} & (A |^ 1) = A by FLANG_1: 24, FLANG_1: 25;

      hence thesis by Th75;

    end;

    theorem :: FLANG_2:77

    A c= (A ? )

    proof

      (A ? ) = ( {( <%> E)} \/ A) by Th76;

      hence thesis by XBOOLE_1: 7;

    end;

    theorem :: FLANG_2:78

    

     Th78: x in (A ? ) iff x = ( <%> E) or x in A

    proof

      x in (A ? ) iff x in ( {( <%> E)} \/ A) by Th76;

      then x in (A ? ) iff x in {( <%> E)} or x in A by XBOOLE_0:def 3;

      hence thesis by TARSKI:def 1;

    end;

    theorem :: FLANG_2:79

    

     Th79: (A ? ) = (A |^ ( 0 ,1))

    proof

      

      thus (A ? ) = ((A |^ 0 ) \/ (A |^ ( 0 + 1))) by Th75

      .= (A |^ ( 0 ,1)) by Th28;

    end;

    theorem :: FLANG_2:80

    

     Th80: (A ? ) = A iff ( <%> E) in A

    proof

      thus (A ? ) = A implies ( <%> E) in A

      proof

        assume (A ? ) = A;

        then A = ( {( <%> E)} \/ A) by Th76;

        hence thesis by ZFMISC_1: 39;

      end;

      assume ( <%> E) in A;

      then A = ( {( <%> E)} \/ A) by ZFMISC_1: 40;

      hence thesis by Th76;

    end;

    registration

      let E, A;

      cluster (A ? ) -> non empty;

      coherence

      proof

        ( <%> E) in (A ? ) by Th78;

        hence thesis;

      end;

    end

    theorem :: FLANG_2:81

    ((A ? ) ? ) = (A ? )

    proof

      ( <%> E) in (A ? ) by Th78;

      hence thesis by Th80;

    end;

    theorem :: FLANG_2:82

    A c= B implies (A ? ) c= (B ? )

    proof

      assume A c= B;

      then (A |^ ( 0 ,1)) c= (B |^ ( 0 ,1)) by Th29;

      then (A ? ) c= (B |^ ( 0 ,1)) by Th79;

      hence thesis by Th79;

    end;

    theorem :: FLANG_2:83

    x in A & x <> ( <%> E) implies (A ? ) <> {( <%> E)}

    proof

      assume

       A1: x in A & x <> ( <%> E);

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by A1, Th30;

    end;

    theorem :: FLANG_2:84

    (A ? ) = {( <%> E)} iff A = {} or A = {( <%> E)}

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by Th31;

    end;

    theorem :: FLANG_2:85

    ((A * ) ? ) = (A * ) & ((A ? ) * ) = (A * )

    proof

      

      thus ((A * ) ? ) = ( {( <%> E)} \/ (A * )) by Th76

      .= (A * ) by FLANG_1: 48, ZFMISC_1: 40;

      

      thus ((A ? ) * ) = (( {( <%> E)} \/ A) * ) by Th76

      .= (A * ) by FLANG_1: 48, FLANG_1: 68;

    end;

    theorem :: FLANG_2:86

    (A ? ) c= (A * )

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by Th32;

    end;

    theorem :: FLANG_2:87

    ((A /\ B) ? ) = ((A ? ) /\ (B ? ))

    proof

      

      thus ((A /\ B) ? ) = ( {( <%> E)} \/ (A /\ B)) by Th76

      .= (( {( <%> E)} \/ A) /\ ( {( <%> E)} \/ B)) by XBOOLE_1: 24

      .= ((A ? ) /\ ( {( <%> E)} \/ B)) by Th76

      .= ((A ? ) /\ (B ? )) by Th76;

    end;

    theorem :: FLANG_2:88

    ((A ? ) \/ (B ? )) = ((A \/ B) ? )

    proof

      

      thus ((A \/ B) ? ) = ( {( <%> E)} \/ (A \/ B)) by Th76

      .= ((A \/ {( <%> E)}) \/ (B \/ {( <%> E)})) by XBOOLE_1: 5

      .= ((A ? ) \/ (B \/ {( <%> E)})) by Th76

      .= ((A ? ) \/ (B ? )) by Th76;

    end;

    theorem :: FLANG_2:89

    (A ? ) = {x} implies x = ( <%> E)

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by Th52;

    end;

    theorem :: FLANG_2:90

     <%x%> in (A ? ) iff <%x%> in A

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by Th53;

    end;

    theorem :: FLANG_2:91

    ((A ? ) ^^ A) = (A ^^ (A ? ))

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      hence thesis by Th36;

    end;

    theorem :: FLANG_2:92

    ((A ? ) ^^ A) = (A |^ (1,2))

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      then ((A ? ) ^^ A) = (A |^ (( 0 + 1),(1 + 1))) by Th38;

      hence thesis;

    end;

    theorem :: FLANG_2:93

    

     Th93: ((A ? ) ^^ (A ? )) = (A |^ ( 0 ,2))

    proof

      (A ? ) = (A |^ ( 0 ,1)) by Th79;

      then ((A ? ) ^^ (A ? )) = (A |^ (( 0 + 0 ),(1 + 1))) by Th37;

      hence thesis;

    end;

    theorem :: FLANG_2:94

    

     Th94: ((A ? ) |^ k) = ((A ? ) |^ ( 0 ,k))

    proof

      ( <%> E) in (A ? ) by Th78;

      hence thesis by Th34;

    end;

    theorem :: FLANG_2:95

    

     Th95: ((A ? ) |^ k) = (A |^ ( 0 ,k))

    proof

      defpred P[ Nat] means ((A ? ) |^ $1) = (A |^ ( 0 ,$1));

       A1:

      now

        let k;

        assume

         A2: P[k];

        ((A ? ) |^ (k + 1)) = (((A ? ) |^ k) ^^ ((A ? ) |^ 1)) by FLANG_1: 33

        .= ((A |^ ( 0 ,k)) ^^ (A ? )) by A2, FLANG_1: 25

        .= ((A |^ ( 0 ,k)) ^^ (A |^ ( 0 ,1))) by Th79

        .= (A |^ (( 0 + 0 ),(k + 1))) by Th37;

        hence P[(k + 1)];

      end;

      ((A ? ) |^ 0 ) = {( <%> E)} by FLANG_1: 24

      .= (A |^ ( 0 , 0 )) by Th45;

      then

       A3: P[ 0 ];

      for k holds P[k] from NAT_1:sch 2( A3, A1);

      hence thesis;

    end;

    theorem :: FLANG_2:96

    

     Th96: m <= n implies ((A ? ) |^ (m,n)) = ((A ? ) |^ ( 0 ,n))

    proof

      assume

       A1: m <= n;

      ( <%> E) in (A ? ) by Th78;

      hence thesis by A1, Th72;

    end;

    theorem :: FLANG_2:97

    

     Th97: ((A ? ) |^ ( 0 ,n)) = (A |^ ( 0 ,n))

    proof

      

      thus ((A ? ) |^ ( 0 ,n)) = ((A ? ) |^ n) by Th94

      .= (A |^ ( 0 ,n)) by Th95;

    end;

    theorem :: FLANG_2:98

    

     Th98: m <= n implies ((A ? ) |^ (m,n)) = (A |^ ( 0 ,n))

    proof

      assume m <= n;

      

      hence ((A ? ) |^ (m,n)) = ((A ? ) |^ ( 0 ,n)) by Th96

      .= (A |^ ( 0 ,n)) by Th97;

    end;

    theorem :: FLANG_2:99

    ((A |^ (1,n)) ? ) = (A |^ ( 0 ,n))

    proof

      

      thus ((A |^ (1,n)) ? ) = ( {( <%> E)} \/ (A |^ (1,n))) by Th76

      .= ((A |^ ( 0 , 0 )) \/ (A |^ (( 0 + 1),n))) by Th45

      .= (A |^ ( 0 ,n)) by Th25;

    end;

    theorem :: FLANG_2:100

    ( <%> E) in A & ( <%> E) in B implies (A ? ) c= (A ^^ B) & (A ? ) c= (B ^^ A)

    proof

      assume that

       A1: ( <%> E) in A and

       A2: ( <%> E) in B;

      ( <%> E) in (B ^^ A) by A1, A2, FLANG_1: 15;

      then

       A3: {( <%> E)} c= (B ^^ A) by ZFMISC_1: 31;

      ( <%> E) in (A ^^ B) by A1, A2, FLANG_1: 15;

      then

       A4: {( <%> E)} c= (A ^^ B) by ZFMISC_1: 31;

      A c= (B ^^ A) by A2, FLANG_1: 16;

      then

       A5: ( {( <%> E)} \/ A) c= (B ^^ A) by A3, XBOOLE_1: 8;

      A c= (A ^^ B) by A2, FLANG_1: 16;

      then ( {( <%> E)} \/ A) c= (A ^^ B) by A4, XBOOLE_1: 8;

      hence thesis by A5, Th76;

    end;

    theorem :: FLANG_2:101

    A c= (A ^^ (B ? )) & A c= ((B ? ) ^^ A)

    proof

      ( <%> E) in (B ? ) by Th78;

      hence thesis by FLANG_1: 16;

    end;

    theorem :: FLANG_2:102

    A c= (C ? ) & B c= (C ? ) implies (A ^^ B) c= (C |^ ( 0 ,2))

    proof

      assume A c= (C ? ) & B c= (C ? );

      then (A ^^ B) c= ((C ? ) ^^ (C ? )) by FLANG_1: 17;

      hence thesis by Th93;

    end;

    theorem :: FLANG_2:103

    ( <%> E) in A & n > 0 implies (A ? ) c= (A |^ n)

    proof

      assume that

       A1: ( <%> E) in A and

       A2: n > 0 ;

      ( <%> E) in (A |^ n) by A1, FLANG_1: 30;

      then

       A3: {( <%> E)} c= (A |^ n) by ZFMISC_1: 31;

      A c= (A |^ n) by A1, A2, FLANG_1: 35;

      then ( {( <%> E)} \/ A) c= (A |^ n) by A3, XBOOLE_1: 8;

      hence thesis by Th76;

    end;

    theorem :: FLANG_2:104

    ((A ? ) ^^ (A |^ k)) = ((A |^ k) ^^ (A ? ))

    proof

      

      thus ((A ? ) ^^ (A |^ k)) = (( {( <%> E)} \/ A) ^^ (A |^ k)) by Th76

      .= (( {( <%> E)} ^^ (A |^ k)) \/ (A ^^ (A |^ k))) by FLANG_1: 20

      .= (( {( <%> E)} ^^ (A |^ k)) \/ ((A |^ k) ^^ A)) by FLANG_1: 32

      .= ((A |^ k) \/ ((A |^ k) ^^ A)) by FLANG_1: 13

      .= (((A |^ k) ^^ {( <%> E)}) \/ ((A |^ k) ^^ A)) by FLANG_1: 13

      .= ((A |^ k) ^^ (A \/ {( <%> E)})) by FLANG_1: 20

      .= ((A |^ k) ^^ (A ? )) by Th76;

    end;

    theorem :: FLANG_2:105

    

     Th105: A c= (B * ) implies (A ? ) c= (B * )

    proof

      assume A c= (B * );

      then (A |^ ( 0 ,1)) c= (B * ) by Th64;

      hence thesis by Th79;

    end;

    theorem :: FLANG_2:106

    A c= (B * ) implies (B * ) = ((B \/ (A ? )) * ) by Th105, FLANG_1: 67;

    theorem :: FLANG_2:107

    ((A ? ) ^^ (A * )) = ((A * ) ^^ (A ? ))

    proof

      

      thus ((A ? ) ^^ (A * )) = ((A |^ ( 0 ,1)) ^^ (A * )) by Th79

      .= ((A * ) ^^ (A |^ ( 0 ,1))) by Th66

      .= ((A * ) ^^ (A ? )) by Th79;

    end;

    theorem :: FLANG_2:108

    ((A ? ) ^^ (A * )) = (A * )

    proof

      

      thus ((A ? ) ^^ (A * )) = (( {( <%> E)} \/ A) ^^ (A * )) by Th76

      .= (( {( <%> E)} ^^ (A * )) \/ (A ^^ (A * ))) by FLANG_1: 20

      .= ((A * ) \/ (A ^^ (A * ))) by FLANG_1: 13

      .= (A * ) by FLANG_1: 53, XBOOLE_1: 12;

    end;

    theorem :: FLANG_2:109

    ((A ? ) |^ k) c= (A * )

    proof

      ((A ? ) |^ k) = ((A |^ ( 0 ,1)) |^ k) by Th79;

      hence thesis by Th32, FLANG_1: 59;

    end;

    theorem :: FLANG_2:110

    ((A |^ k) ? ) c= (A * )

    proof

      ((A |^ k) ? ) = ((A |^ k) |^ ( 0 ,1)) by Th79;

      hence thesis by Th69;

    end;

    theorem :: FLANG_2:111

    ((A ? ) ^^ (A |^ (m,n))) = ((A |^ (m,n)) ^^ (A ? ))

    proof

      ((A |^ ( 0 ,1)) ^^ (A |^ (m,n))) = ((A |^ (m,n)) ^^ (A |^ ( 0 ,1))) by Th39;

      then ((A ? ) ^^ (A |^ (m,n))) = ((A |^ (m,n)) ^^ (A |^ ( 0 ,1))) by Th79;

      hence thesis by Th79;

    end;

    theorem :: FLANG_2:112

    ((A ? ) ^^ (A |^ k)) = (A |^ (k,(k + 1)))

    proof

      ((A |^ ( 0 ,1)) ^^ (A |^ k)) = ((A |^ ( 0 ,1)) ^^ (A |^ (k,k))) by Th22

      .= (A |^ (( 0 + k),(1 + k))) by Th37;

      hence thesis by Th79;

    end;

    theorem :: FLANG_2:113

    ((A ? ) |^ (m,n)) c= (A * )

    proof

      per cases ;

        suppose m <= n;

        then ((A ? ) |^ (m,n)) = (A |^ ( 0 ,n)) by Th98;

        hence thesis by Th32;

      end;

        suppose m > n;

        then ((A ? ) |^ (m,n)) = {} by Th21;

        hence thesis;

      end;

    end;

    theorem :: FLANG_2:114

    ((A |^ (m,n)) ? ) c= (A * )

    proof

      ((A |^ (m,n)) ? ) = ((A |^ (m,n)) |^ ( 0 ,1)) by Th79;

      hence thesis by Th71;

    end;

    theorem :: FLANG_2:115

    (A ? ) = ((A \ {( <%> E)}) ? )

    proof

      

      thus (A ? ) = ( {( <%> E)} \/ A) by Th76

      .= ( {( <%> E)} \/ (A \ {( <%> E)})) by XBOOLE_1: 39

      .= ((A \ {( <%> E)}) ? ) by Th76;

    end;

    theorem :: FLANG_2:116

    A c= (B ? ) implies (A ? ) c= (B ? )

    proof

      ( <%> E) in (B ? ) by Th78;

      then

       A1: {( <%> E)} c= (B ? ) by ZFMISC_1: 31;

      assume A c= (B ? );

      then ( {( <%> E)} \/ A) c= (B ? ) by A1, XBOOLE_1: 8;

      hence thesis by Th76;

    end;

    theorem :: FLANG_2:117

    A c= (B ? ) implies (B ? ) = ((B \/ A) ? )

    proof

      assume

       A1: A c= (B ? );

      

      thus ((B \/ A) ? ) = ( {( <%> E)} \/ (B \/ A)) by Th76

      .= (( {( <%> E)} \/ B) \/ A) by XBOOLE_1: 4

      .= ((B ? ) \/ A) by Th76

      .= (B ? ) by A1, XBOOLE_1: 12;

    end;