lopban_9.miz



    begin

    

     LMELM1: for X,Y be RealLinearSpace, x be Point of X, y be Point of Y holds [x, y] is Point of [:X, Y:]

    proof

      let X,Y be RealLinearSpace, x be Point of X, y be Point of Y;

       [x, y] is set by TARSKI: 1;

      hence [x, y] is Point of [:X, Y:] by PRVECT_3: 9;

    end;

    definition

      let X,Y,Z be RealLinearSpace;

      :: LOPBAN_9:def1

      func BilinearOperators (X,Y,Z) -> Subset of ( RealVectSpace (the carrier of [:X, Y:],Z)) means

      : Def6: for x be set holds x in it iff x is BilinearOperator of X, Y, Z;

      existence

      proof

        defpred P[ object] means $1 is BilinearOperator of X, Y, Z;

        consider IT be set such that

         A1: for x be object holds x in IT iff x in ( Funcs (the carrier of [:X, Y:],the carrier of Z)) & P[x] from XBOOLE_0:sch 1;

        take IT;

        for x be object st x in IT holds x in ( Funcs (the carrier of [:X, Y:],the carrier of Z)) by A1;

        hence IT is Subset of ( RealVectSpace (the carrier of [:X, Y:],Z)) by TARSKI:def 3;

        let x be set;

        thus x in IT implies x is BilinearOperator of X, Y, Z by A1;

        assume

         A2: x is BilinearOperator of X, Y, Z;

        then x in ( Funcs (the carrier of [:X, Y:],the carrier of Z)) by FUNCT_2: 8;

        hence thesis by A1, A2;

      end;

      uniqueness

      proof

        let X1,X2 be Subset of ( RealVectSpace (the carrier of [:X, Y:],Z));

        assume that

         A3: for x be set holds x in X1 iff x is BilinearOperator of X, Y, Z and

         A4: for x be set holds x in X2 iff x is BilinearOperator of X, Y, Z;

        

         A5: X2 c= X1

        proof

          let x be object;

          assume x in X2;

          then x is BilinearOperator of X, Y, Z by A4;

          hence thesis by A3;

        end;

        X1 c= X2

        proof

          let x be object;

          assume x in X1;

          then x is BilinearOperator of X, Y, Z by A3;

          hence thesis by A4;

        end;

        hence thesis by A5, XBOOLE_0:def 10;

      end;

    end

    registration

      let X,Y,Z be RealLinearSpace;

      cluster ( BilinearOperators (X,Y,Z)) -> non empty functional;

      coherence

      proof

        set f = the BilinearOperator of X, Y, Z;

        f in ( BilinearOperators (X,Y,Z)) by Def6;

        hence ( BilinearOperators (X,Y,Z)) is non empty;

        let x be object;

        assume x in ( BilinearOperators (X,Y,Z));

        hence thesis;

      end;

    end

    

     LM14: for X be RealLinearSpace, x1,x2,x3,x4 be Point of X holds ((x1 + x2) + (x3 + x4)) = ((x1 + x3) + (x2 + x4))

    proof

      let X be RealLinearSpace, x1,x2,x3,x4 be Point of X;

      

      thus ((x1 + x2) + (x3 + x4)) = (((x1 + x2) + x3) + x4) by RLVECT_1:def 3

      .= (((x1 + x3) + x2) + x4) by RLVECT_1:def 3

      .= ((x1 + x3) + (x2 + x4)) by RLVECT_1:def 3;

    end;

    

     Th14: for X,Y,Z be RealLinearSpace holds ( BilinearOperators (X,Y,Z)) is linearly-closed

    proof

      let X,Y,Z be RealLinearSpace;

      set W = ( BilinearOperators (X,Y,Z));

      

       A1: for v,u be VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) st v in ( BilinearOperators (X,Y,Z)) & u in ( BilinearOperators (X,Y,Z)) holds (v + u) in ( BilinearOperators (X,Y,Z))

      proof

        let v,u be VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) such that

         A2: v in W and

         A3: u in W;

        reconsider u1 = u as BilinearOperator of X, Y, Z by A3, Def6;

        reconsider v1 = v as BilinearOperator of X, Y, Z by A2, Def6;

        (v + u) is BilinearOperator of X, Y, Z

        proof

          reconsider L = (v + u) as Function of [:X, Y:], Z by FUNCT_2: 66;

          

           A4: for x1,x2 be Point of X, y be Point of Y holds (L . ((x1 + x2),y)) = ((L . (x1,y)) + (L . (x2,y)))

          proof

            let x1,x2 be Point of X, y be Point of Y;

            

             A5: [x1, y] is Element of [:X, Y:] & [x2, y] is Element of [:X, Y:] & [(x1 + x2), y] is Element of [:X, Y:] by LMELM1;

            

            hence (L . ((x1 + x2),y)) = ((v1 . ((x1 + x2),y)) + (u1 . ((x1 + x2),y))) by LOPBAN_1: 1

            .= (((v1 . (x1,y)) + (v1 . (x2,y))) + (u1 . ((x1 + x2),y))) by LOPBAN_8: 11

            .= (((v1 . (x1,y)) + (v1 . (x2,y))) + ((u1 . (x1,y)) + (u1 . (x2,y)))) by LOPBAN_8: 11

            .= (((v1 . (x1,y)) + (u1 . (x1,y))) + ((v1 . (x2,y)) + (u1 . (x2,y)))) by LM14

            .= ((L . (x1,y)) + ((v1 . (x2,y)) + (u1 . (x2,y)))) by A5, LOPBAN_1: 1

            .= ((L . (x1,y)) + (L . (x2,y))) by A5, LOPBAN_1: 1;

          end;

          

           A6: for x be Point of X, y be Point of Y, a be Real holds (L . ((a * x),y)) = (a * (L . (x,y)))

          proof

            let x be Point of X, y be Point of Y, a be Real;

            

             A7: [x, y] is Element of [:X, Y:] & [(a * x), y] is Element of [:X, Y:] by LMELM1;

            

            hence (L . ((a * x),y)) = ((v1 . ((a * x),y)) + (u1 . ((a * x),y))) by LOPBAN_1: 1

            .= ((a * (v1 . (x,y))) + (u1 . ((a * x),y))) by LOPBAN_8: 11

            .= ((a * (v1 . (x,y))) + (a * (u1 . (x,y)))) by LOPBAN_8: 11

            .= (a * ((v1 . (x,y)) + (u1 . (x,y)))) by RLVECT_1:def 5

            .= (a * (L . (x,y))) by A7, LOPBAN_1: 1;

          end;

          

           A8: for x be Point of X, y1,y2 be Point of Y holds (L . (x,(y1 + y2))) = ((L . (x,y1)) + (L . (x,y2)))

          proof

            let x be Point of X, y1,y2 be Point of Y;

            

             A9: [x, y1] is Element of [:X, Y:] & [x, y2] is Element of [:X, Y:] & [x, (y1 + y2)] is Element of [:X, Y:] by LMELM1;

            

            hence (L . (x,(y1 + y2))) = ((v1 . (x,(y1 + y2))) + (u1 . (x,(y1 + y2)))) by LOPBAN_1: 1

            .= (((v1 . (x,y1)) + (v1 . (x,y2))) + (u1 . (x,(y1 + y2)))) by LOPBAN_8: 11

            .= (((v1 . (x,y1)) + (v1 . (x,y2))) + ((u1 . (x,y1)) + (u1 . (x,y2)))) by LOPBAN_8: 11

            .= (((v1 . (x,y1)) + (u1 . (x,y1))) + ((v1 . (x,y2)) + (u1 . (x,y2)))) by LM14

            .= ((L . (x,y1)) + ((v1 . (x,y2)) + (u1 . (x,y2)))) by A9, LOPBAN_1: 1

            .= ((L . (x,y1)) + (L . (x,y2))) by A9, LOPBAN_1: 1;

          end;

          for x be Point of X, y be Point of Y, a be Real holds (L . (x,(a * y))) = (a * (L . (x,y)))

          proof

            let x be Point of X, y be Point of Y, a be Real;

            

             A10: [x, y] is Element of [:X, Y:] & [x, (a * y)] is Element of [:X, Y:] by LMELM1;

            

            hence (L . (x,(a * y))) = ((v1 . (x,(a * y))) + (u1 . (x,(a * y)))) by LOPBAN_1: 1

            .= ((a * (v1 . (x,y))) + (u1 . (x,(a * y)))) by LOPBAN_8: 11

            .= ((a * (v1 . (x,y))) + (a * (u1 . (x,y)))) by LOPBAN_8: 11

            .= (a * ((v1 . (x,y)) + (u1 . (x,y)))) by RLVECT_1:def 5

            .= (a * (L . (x,y))) by A10, LOPBAN_1: 1;

          end;

          hence thesis by A4, A6, A8, LOPBAN_8: 11;

        end;

        hence thesis by Def6;

      end;

      for b be Real holds for v be VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) st v in W holds (b * v) in W

      proof

        let b be Real;

        let v be VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) such that

         A11: v in W;

        reconsider v1 = v as BilinearOperator of X, Y, Z by A11, Def6;

        (b * v) is BilinearOperator of X, Y, Z

        proof

          reconsider L = (b * v) as Function of [:X, Y:], Z by FUNCT_2: 66;

          

           A12: for x1,x2 be Point of X, y be Point of Y holds (L . ((x1 + x2),y)) = ((L . (x1,y)) + (L . (x2,y)))

          proof

            let x1,x2 be Point of X, y be Point of Y;

            

             A13: [x1, y] is Element of [:X, Y:] & [x2, y] is Element of [:X, Y:] & [(x1 + x2), y] is Element of [:X, Y:] by LMELM1;

            

            hence (L . ((x1 + x2),y)) = (b * (v1 . ((x1 + x2),y))) by LOPBAN_1: 2

            .= (b * ((v1 . (x1,y)) + (v1 . (x2,y)))) by LOPBAN_8: 11

            .= ((b * (v1 . (x1,y))) + (b * (v1 . (x2,y)))) by RLVECT_1:def 5

            .= ((L . (x1,y)) + (b * (v1 . (x2,y)))) by A13, LOPBAN_1: 2

            .= ((L . (x1,y)) + (L . (x2,y))) by A13, LOPBAN_1: 2;

          end;

          

           A14: for x be Point of X, y be Point of Y, a be Real holds (L . ((a * x),y)) = (a * (L . (x,y)))

          proof

            let x be Point of X, y be Point of Y, a be Real;

            

             A15: [x, y] is Element of [:X, Y:] & [(a * x), y] is Element of [:X, Y:] by LMELM1;

            

            hence (L . ((a * x),y)) = (b * (v1 . ((a * x),y))) by LOPBAN_1: 2

            .= (b * (a * (v1 . (x,y)))) by LOPBAN_8: 11

            .= ((b * a) * (v1 . (x,y))) by RLVECT_1:def 7

            .= (a * (b * (v1 . (x,y)))) by RLVECT_1:def 7

            .= (a * (L . (x,y))) by A15, LOPBAN_1: 2;

          end;

          

           A16: for x be Point of X, y1,y2 be Point of Y holds (L . (x,(y1 + y2))) = ((L . (x,y1)) + (L . (x,y2)))

          proof

            let x be Point of X, y1,y2 be Point of Y;

            

             A17: [x, y1] is Element of [:X, Y:] & [x, y2] is Element of [:X, Y:] & [x, (y1 + y2)] is Element of [:X, Y:] by LMELM1;

            

            hence (L . (x,(y1 + y2))) = (b * (v1 . (x,(y1 + y2)))) by LOPBAN_1: 2

            .= (b * ((v1 . (x,y1)) + (v1 . (x,y2)))) by LOPBAN_8: 11

            .= ((b * (v1 . (x,y1))) + (b * (v1 . (x,y2)))) by RLVECT_1:def 5

            .= ((L . (x,y1)) + (b * (v1 . (x,y2)))) by A17, LOPBAN_1: 2

            .= ((L . (x,y1)) + (L . (x,y2))) by A17, LOPBAN_1: 2;

          end;

          for x be Point of X, y be Point of Y, a be Real holds (L . (x,(a * y))) = (a * (L . (x,y)))

          proof

            let x be Point of X, y be Point of Y, a be Real;

            

             A18: [x, y] is Element of [:X, Y:] & [x, (a * y)] is Element of [:X, Y:] by LMELM1;

            

            hence (L . (x,(a * y))) = (b * (v1 . (x,(a * y)))) by LOPBAN_1: 2

            .= (b * (a * (v1 . (x,y)))) by LOPBAN_8: 11

            .= ((b * a) * (v1 . (x,y))) by RLVECT_1:def 7

            .= (a * (b * (v1 . (x,y)))) by RLVECT_1:def 7

            .= (a * (L . (x,y))) by A18, LOPBAN_1: 2;

          end;

          hence thesis by A12, A14, A16, LOPBAN_8: 11;

        end;

        hence thesis by Def6;

      end;

      hence thesis by A1, RLSUB_1:def 1;

    end;

    registration

      let X,Y,Z be RealLinearSpace;

      cluster ( BilinearOperators (X,Y,Z)) -> linearly-closed;

      coherence by Th14;

    end

    definition

      let X,Y,Z be RealLinearSpace;

      :: LOPBAN_9:def2

      func R_VectorSpace_of_BilinearOperators (X,Y,Z) -> strict RLSStruct equals RLSStruct (# ( BilinearOperators (X,Y,Z)), ( Zero_ (( BilinearOperators (X,Y,Z)),( RealVectSpace (the carrier of [:X, Y:],Z)))), ( Add_ (( BilinearOperators (X,Y,Z)),( RealVectSpace (the carrier of [:X, Y:],Z)))), ( Mult_ (( BilinearOperators (X,Y,Z)),( RealVectSpace (the carrier of [:X, Y:],Z)))) #);

      coherence ;

    end

    registration

      let X,Y,Z be RealLinearSpace;

      cluster ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) -> non empty;

      coherence ;

    end

    registration

      let X,Y,Z be RealLinearSpace;

      cluster ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) -> Abelian add-associative right_zeroed right_complementable vector-distributive scalar-distributive scalar-associative scalar-unital;

      coherence by RSSPACE: 11;

    end

    registration

      let X,Y,Z be RealLinearSpace;

      cluster ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) -> constituted-Functions;

      coherence by MONOID_0: 80;

    end

    theorem :: LOPBAN_9:1

    for X,Y,Z be RealLinearSpace holds ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) is Subspace of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RSSPACE: 11;

    definition

      let X,Y,Z be RealLinearSpace;

      let f be Element of ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

      let v be VECTOR of X, w be VECTOR of Y;

      :: original: .

      redefine

      func f . (v,w) -> VECTOR of Z ;

      coherence

      proof

        reconsider f as BilinearOperator of X, Y, Z by Def6;

        (f . (v,w)) is VECTOR of Z;

        hence thesis;

      end;

    end

    theorem :: LOPBAN_9:2

    

     Th16: for X,Y,Z be RealLinearSpace holds for f,g,h be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) holds h = (f + g) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) + (g . (x,y)))

    proof

      let X,Y,Z be RealLinearSpace;

      let f,g,h be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

      reconsider f9 = f, g9 = g, h9 = h as BilinearOperator of X, Y, Z by Def6;

      

       A1: ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) is Subspace of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RSSPACE: 11;

      then

      reconsider f1 = f as VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RLSUB_1: 10;

      reconsider h1 = h as VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) by A1, RLSUB_1: 10;

      reconsider g1 = g as VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) by A1, RLSUB_1: 10;

       A2:

      now

        assume

         A3: h = (f + g);

        let x be Element of X, y be Element of Y;

        

         A4: h1 = (f1 + g1) by A1, A3, RLSUB_1: 13;

         [x, y] is Element of [:X, Y:] by LMELM1;

        hence (h9 . (x,y)) = ((f9 . (x,y)) + (g9 . (x,y))) by A4, LOPBAN_1: 1;

      end;

      now

        assume

         A5: for x be Element of X, y be Element of Y holds (h9 . (x,y)) = ((f9 . (x,y)) + (g9 . (x,y)));

        for z be Element of [:X, Y:] holds (h9 . z) = ((f9 . z) + (g9 . z))

        proof

          let z be Element of [:X, Y:];

          consider x be Point of X, y be Point of Y such that

           A6: z = [x, y] by PRVECT_3: 9;

          

          thus (h9 . z) = (h9 . (x,y)) by A6

          .= ((f9 . (x,y)) + (g9 . (x,y))) by A5

          .= ((f9 . z) + (g9 . z)) by A6;

        end;

        then h1 = (f1 + g1) by LOPBAN_1: 1;

        hence h = (f + g) by A1, RLSUB_1: 13;

      end;

      hence thesis by A2;

    end;

    theorem :: LOPBAN_9:3

    

     Th17: for X,Y,Z be RealLinearSpace holds for f,h be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) holds for a be Real holds h = (a * f) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = (a * (f . (x,y)))

    proof

      let X,Y,Z be RealLinearSpace;

      let f,h be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

      reconsider f9 = f, h9 = h as BilinearOperator of X, Y, Z by Def6;

      let a be Real;

      

       A1: ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) is Subspace of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RSSPACE: 11;

      then

      reconsider f1 = f as VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RLSUB_1: 10;

      reconsider h1 = h as VECTOR of ( RealVectSpace (the carrier of [:X, Y:],Z)) by A1, RLSUB_1: 10;

       A2:

      now

        assume

         A3: h = (a * f);

        let x be Element of X, y be Element of Y;

        

         A4: h1 = (a * f1) by A1, A3, RLSUB_1: 14;

         [x, y] is Element of [:X, Y:] by LMELM1;

        hence (h9 . (x,y)) = (a * (f9 . (x,y))) by A4, LOPBAN_1: 2;

      end;

      now

        assume

         A5: for x be Element of X, y be Element of Y holds (h9 . (x,y)) = (a * (f9 . (x,y)));

        for z be Element of [:X, Y:] holds (h9 . z) = (a * (f9 . z))

        proof

          let z be Element of [:X, Y:];

          consider x be Point of X, y be Point of Y such that

           A6: z = [x, y] by PRVECT_3: 9;

          

          thus (h9 . z) = (h9 . (x,y)) by A6

          .= (a * (f9 . (x,y))) by A5

          .= (a * (f9 . z)) by A6;

        end;

        then h1 = (a * f1) by LOPBAN_1: 2;

        hence h = (a * f) by A1, RLSUB_1: 14;

      end;

      hence thesis by A2;

    end;

    theorem :: LOPBAN_9:4

    

     Th18: for X,Y,Z be RealLinearSpace holds ( 0. ( R_VectorSpace_of_BilinearOperators (X,Y,Z))) = (the carrier of [:X, Y:] --> ( 0. Z))

    proof

      let X,Y,Z be RealLinearSpace;

      

       A1: ( 0. ( RealVectSpace (the carrier of [:X, Y:],Z))) = (the carrier of [:X, Y:] --> ( 0. Z));

      ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) is Subspace of ( RealVectSpace (the carrier of [:X, Y:],Z)) by RSSPACE: 11;

      hence thesis by A1, RLSUB_1: 11;

    end;

    theorem :: LOPBAN_9:5

    for X,Y,Z be RealLinearSpace holds (the carrier of [:X, Y:] --> ( 0. Z)) is BilinearOperator of X, Y, Z by LOPBAN_8: 9, LOPBAN_8:def 2;

    begin

    

     LMELM2: for X,Y be RealNormSpace, x be Point of X, y be Point of Y holds [x, y] is Point of [:X, Y:]

    proof

      let X,Y be RealNormSpace, x be Point of X, y be Point of Y;

       [x, y] is set by TARSKI: 1;

      hence [x, y] is Point of [:X, Y:] by PRVECT_3: 18;

    end;

    definition

      let X,Y,Z be RealNormSpace;

      let IT be BilinearOperator of X, Y, Z;

      :: LOPBAN_9:def3

      attr IT is Lipschitzian means

      : Def8: ex K be Real st 0 <= K & for x be VECTOR of X, y be VECTOR of Y holds ||.(IT . (x,y)).|| <= ((K * ||.x.||) * ||.y.||);

    end

    theorem :: LOPBAN_9:6

    

     Th21: for X,Y,Z be RealNormSpace holds for f be BilinearOperator of X, Y, Z st (for x be VECTOR of X, y be VECTOR of Y holds (f . (x,y)) = ( 0. Z)) holds f is Lipschitzian

    proof

      let X,Y,Z be RealNormSpace;

      let f be BilinearOperator of X, Y, Z such that

       A1: for x be VECTOR of X, y be VECTOR of Y holds (f . (x,y)) = ( 0. Z);

       A2:

      now

        let x be VECTOR of X, y be VECTOR of Y;

        

        thus ||.(f . (x,y)).|| = ||.( 0. Z).|| by A1

        .= (( 0 * ||.x.||) * ||.y.||);

      end;

      take 0 ;

      thus thesis by A2;

    end;

    theorem :: LOPBAN_9:7

    for X,Y,Z be RealNormSpace holds (the carrier of [:X, Y:] --> ( 0. Z)) is BilinearOperator of X, Y, Z by LOPBAN_8: 9, LOPBAN_8:def 3;

    registration

      let X,Y,Z be RealNormSpace;

      cluster Lipschitzian for BilinearOperator of X, Y, Z;

      existence

      proof

        set f = (the carrier of [:X, Y:] --> ( 0. Z));

        reconsider f as BilinearOperator of X, Y, Z by LOPBAN_8: 9, LOPBAN_8:def 3;

        take f;

        for x be VECTOR of X, y be VECTOR of Y holds (f . (x,y)) = ( 0. Z)

        proof

          let x be VECTOR of X, y be VECTOR of Y;

           [x, y] is Point of [:X, Y:] by LMELM2;

          hence thesis by FUNCOP_1: 7;

        end;

        hence thesis by Th21;

      end;

    end

    theorem :: LOPBAN_9:8

    

     EQSET: for X,Y,Z be RealNormSpace, z be object holds (z in ( BilinearOperators (X,Y,Z)) iff z is BilinearOperator of X, Y, Z)

    proof

      let X,Y,Z be RealNormSpace, z be object;

      reconsider X0 = X, Y0 = Y, Z0 = Z as RealLinearSpace;

      hereby

        assume z in ( BilinearOperators (X,Y,Z));

        then z is BilinearOperator of X0, Y0, Z0 by Def6;

        then

        consider g be Function of [:the carrier of X0, the carrier of Y0:], the carrier of Z0 such that

         A1: z = g & g is Bilinear by LOPBAN_8:def 2;

        thus z is BilinearOperator of X, Y, Z by A1, LOPBAN_8:def 3;

      end;

      assume z is BilinearOperator of X, Y, Z;

      then

      consider g be Function of [:the carrier of X, the carrier of Y:], the carrier of Z such that

       A1: z = g & g is Bilinear by LOPBAN_8:def 3;

      reconsider w = g as BilinearOperator of X0, Y0, Z0 by LOPBAN_8:def 2, A1;

      w in ( BilinearOperators (X,Y,Z)) by Def6;

      hence z in ( BilinearOperators (X,Y,Z)) by A1;

    end;

    definition

      let X,Y,Z be RealNormSpace;

      :: LOPBAN_9:def4

      func BoundedBilinearOperators (X,Y,Z) -> Subset of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) means

      : Def9: for x be set holds x in it iff x is Lipschitzian BilinearOperator of X, Y, Z;

      existence

      proof

        defpred P[ object] means $1 is Lipschitzian BilinearOperator of X, Y, Z;

        consider IT be set such that

         A1: for x be object holds x in IT iff x in ( BilinearOperators (X,Y,Z)) & P[x] from XBOOLE_0:sch 1;

        take IT;

        for x be object st x in IT holds x in ( BilinearOperators (X,Y,Z)) by A1;

        hence IT is Subset of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by TARSKI:def 3;

        let x be set;

        thus x in IT implies x is Lipschitzian BilinearOperator of X, Y, Z by A1;

        assume x is Lipschitzian BilinearOperator of X, Y, Z;

        hence thesis by A1, EQSET;

      end;

      uniqueness

      proof

        let X1,X2 be Subset of ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

        assume that

         A3: for x be set holds x in X1 iff x is Lipschitzian BilinearOperator of X, Y, Z and

         A4: for x be set holds x in X2 iff x is Lipschitzian BilinearOperator of X, Y, Z;

        

         A5: X2 c= X1

        proof

          let x be object;

          assume x in X2;

          then x is Lipschitzian BilinearOperator of X, Y, Z by A4;

          hence thesis by A3;

        end;

        X1 c= X2

        proof

          let x be object;

          assume x in X1;

          then x is Lipschitzian BilinearOperator of X, Y, Z by A3;

          hence thesis by A4;

        end;

        hence thesis by A5, XBOOLE_0:def 10;

      end;

    end

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( BoundedBilinearOperators (X,Y,Z)) -> non empty;

      coherence

      proof

        set f = (the carrier of [:X, Y:] --> ( 0. Z));

        reconsider f as BilinearOperator of X, Y, Z by LOPBAN_8: 9, LOPBAN_8:def 3;

        for x be VECTOR of X, y be VECTOR of Y holds (f . (x,y)) = ( 0. Z)

        proof

          let x be VECTOR of X, y be VECTOR of Y;

           [x, y] is Point of [:X, Y:] by LMELM2;

          hence thesis by FUNCOP_1: 7;

        end;

        then f is Lipschitzian by Th21;

        hence thesis by Def9;

      end;

    end

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( BoundedBilinearOperators (X,Y,Z)) -> linearly-closed;

      coherence

      proof

        set W = ( BoundedBilinearOperators (X,Y,Z));

        

         A1: for v,u be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) st v in W & u in W holds (v + u) in W

        proof

          let v,u be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) such that

           A2: v in W and

           A3: u in W;

          reconsider f = (v + u) as BilinearOperator of X, Y, Z by EQSET;

          f is Lipschitzian

          proof

            reconsider v1 = v as Lipschitzian BilinearOperator of X, Y, Z by A2, Def9;

            consider K2 be Real such that

             A4: 0 <= K2 and

             A5: for x be VECTOR of X, y be VECTOR of Y holds ||.(v1 . (x,y)).|| <= ((K2 * ||.x.||) * ||.y.||) by Def8;

            reconsider u1 = u as Lipschitzian BilinearOperator of X, Y, Z by A3, Def9;

            consider K1 be Real such that

             A6: 0 <= K1 and

             A7: for x be VECTOR of X, y be VECTOR of Y holds ||.(u1 . (x,y)).|| <= ((K1 * ||.x.||) * ||.y.||) by Def8;

            take K3 = (K1 + K2);

            now

              let x be VECTOR of X, y be VECTOR of Y;

              

               A8: ||.((u1 . (x,y)) + (v1 . (x,y))).|| <= ( ||.(u1 . (x,y)).|| + ||.(v1 . (x,y)).||) by NORMSP_1:def 1;

              

               A9: ||.(v1 . (x,y)).|| <= ((K2 * ||.x.||) * ||.y.||) by A5;

               ||.(u1 . (x,y)).|| <= ((K1 * ||.x.||) * ||.y.||) by A7;

              then

               A10: ( ||.(u1 . (x,y)).|| + ||.(v1 . (x,y)).||) <= (((K1 * ||.x.||) * ||.y.||) + ((K2 * ||.x.||) * ||.y.||)) by A9, XREAL_1: 7;

               ||.(f . (x,y)).|| = ||.((u1 . (x,y)) + (v1 . (x,y))).|| by Th16;

              hence ||.(f . (x,y)).|| <= ((K3 * ||.x.||) * ||.y.||) by A8, A10, XXREAL_0: 2;

            end;

            hence thesis by A4, A6;

          end;

          hence thesis by Def9;

        end;

        for a be Real holds for v be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) st v in W holds (a * v) in W

        proof

          let a be Real;

          let v be VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) such that

           A11: v in W;

          reconsider f = (a * v) as BilinearOperator of X, Y, Z by EQSET;

          f is Lipschitzian

          proof

            reconsider v1 = v as Lipschitzian BilinearOperator of X, Y, Z by A11, Def9;

            consider K be Real such that

             A12: 0 <= K and

             A13: for x be VECTOR of X, y be VECTOR of Y holds ||.(v1 . (x,y)).|| <= ((K * ||.x.||) * ||.y.||) by Def8;

            take ( |.a.| * K);

             A14:

            now

              let x be VECTOR of X, y be VECTOR of Y;

               0 <= |.a.| by COMPLEX1: 46;

              then

               A15: ( |.a.| * ||.(v1 . (x,y)).||) <= ( |.a.| * ((K * ||.x.||) * ||.y.||)) by A13, XREAL_1: 64;

               ||.(a * (v1 . (x,y))).|| = ( |.a.| * ||.(v1 . (x,y)).||) by NORMSP_1:def 1;

              hence ||.(f . (x,y)).|| <= ((( |.a.| * K) * ||.x.||) * ||.y.||) by A15, Th17;

            end;

             0 <= |.a.| by COMPLEX1: 46;

            hence thesis by A12, A14;

          end;

          hence thesis by Def9;

        end;

        hence thesis by A1, RLSUB_1:def 1;

      end;

    end

    definition

      let X,Y,Z be RealNormSpace;

      :: LOPBAN_9:def5

      func R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z) -> strict RLSStruct equals RLSStruct (# ( BoundedBilinearOperators (X,Y,Z)), ( Zero_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))), ( Add_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))), ( Mult_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))) #);

      coherence ;

    end

    theorem :: LOPBAN_9:9

    for X,Y,Z be RealNormSpace holds ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) is Subspace of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RSSPACE: 11;

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) -> non empty;

      coherence ;

    end

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) -> Abelian add-associative right_zeroed right_complementable vector-distributive scalar-distributive scalar-associative scalar-unital;

      coherence by RSSPACE: 11;

    end

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) -> constituted-Functions;

      coherence by MONOID_0: 80;

    end

    definition

      let X,Y,Z be RealNormSpace;

      let f be Element of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      let v be VECTOR of X, w be VECTOR of Y;

      :: original: .

      redefine

      func f . (v,w) -> VECTOR of Z ;

      coherence

      proof

        reconsider f as BilinearOperator of X, Y, Z by Def9;

        (f . (v,w)) is VECTOR of Z;

        hence thesis;

      end;

    end

    theorem :: LOPBAN_9:10

    

     Th24: for X,Y,Z be RealNormSpace holds for f,g,h be VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) holds h = (f + g) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) + (g . (x,y)))

    proof

      let X,Y,Z be RealNormSpace;

      let f,g,h be VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      

       A1: ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) is Subspace of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RSSPACE: 11;

      then

      reconsider f1 = f as VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RLSUB_1: 10;

      reconsider h1 = h as VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by A1, RLSUB_1: 10;

      reconsider g1 = g as VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by A1, RLSUB_1: 10;

      hereby

        assume

         A2: h = (f + g);

        let x be Element of X, y be Element of Y;

        h1 = (f1 + g1) by A1, A2, RLSUB_1: 13;

        hence (h . (x,y)) = ((f . (x,y)) + (g . (x,y))) by Th16;

      end;

      assume for x be Element of X, y be Element of Y holds (h . (x,y)) = ((f . (x,y)) + (g . (x,y)));

      then h1 = (f1 + g1) by Th16;

      hence thesis by A1, RLSUB_1: 13;

    end;

    theorem :: LOPBAN_9:11

    

     Th25: for X,Y,Z be RealNormSpace holds for f,h be VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) holds for a be Real holds h = (a * f) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = (a * (f . (x,y)))

    proof

      let X,Y,Z be RealNormSpace;

      let f,h be VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      let a be Real;

      

       A1: ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) is Subspace of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RSSPACE: 11;

      then

      reconsider f1 = f as VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RLSUB_1: 10;

      reconsider h1 = h as VECTOR of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by A1, RLSUB_1: 10;

      hereby

        assume

         A2: h = (a * f);

        let x be Element of X, y be Element of Y;

        h1 = (a * f1) by A1, A2, RLSUB_1: 14;

        hence (h . (x,y)) = (a * (f . (x,y))) by Th17;

      end;

      assume for x be Element of X, y be Element of Y holds (h . (x,y)) = (a * (f . (x,y)));

      then h1 = (a * f1) by Th17;

      hence thesis by A1, RLSUB_1: 14;

    end;

    theorem :: LOPBAN_9:12

    

     Th26: for X,Y,Z be RealNormSpace holds ( 0. ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z))) = (the carrier of [:X, Y:] --> ( 0. Z))

    proof

      let X,Y,Z be RealNormSpace;

      

       A1: ( 0. ( R_VectorSpace_of_BilinearOperators (X,Y,Z))) = (the carrier of [:X, Y:] --> ( 0. Z)) by Th18;

      ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) is Subspace of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by RSSPACE: 11;

      hence thesis by A1, RLSUB_1: 11;

    end;

    definition

      let X,Y,Z be RealNormSpace;

      let f be object;

      :: LOPBAN_9:def6

      func modetrans (f,X,Y,Z) -> Lipschitzian BilinearOperator of X, Y, Z equals

      : Def11: f;

      coherence by A1, Def9;

    end

    definition

      let X,Y,Z be RealNormSpace;

      let u be BilinearOperator of X, Y, Z;

      :: LOPBAN_9:def7

      func PreNorms (u) -> non empty Subset of REAL equals { ||.(u . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 };

      coherence

      proof

         A1:

        now

          let x be object;

          now

            assume x in { ||.(u . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 };

            then ex t be VECTOR of X, s be VECTOR of Y st x = ||.(u . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

            hence x in REAL ;

          end;

          hence x in { ||.(u . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 } implies x in REAL ;

        end;

         ||.( 0. X).|| = 0 & ||.( 0. Y).|| = 0 ;

        then ||.(u . (( 0. X),( 0. Y))).|| in { ||.(u . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 };

        hence thesis by A1, TARSKI:def 3;

      end;

    end

    registration

      let X,Y,Z be RealNormSpace;

      let g be Lipschitzian BilinearOperator of X, Y, Z;

      cluster ( PreNorms g) -> bounded_above;

      coherence

      proof

        consider K be Real such that

         A1: 0 <= K and

         A2: for x be VECTOR of X, y be VECTOR of Y holds ||.(g . (x,y)).|| <= ((K * ||.x.||) * ||.y.||) by Def8;

        take K;

        let r be ExtReal;

        assume r in ( PreNorms g);

        then

        consider t be VECTOR of X, s be VECTOR of Y such that

         A3: r = ||.(g . (t,s)).|| and

         A4: ||.t.|| <= 1 & ||.s.|| <= 1;

        

         A5: ||.(g . (t,s)).|| <= ((K * ||.t.||) * ||.s.||) by A2;

        ( ||.t.|| * ||.s.||) <= (1 * 1) by XREAL_1: 66, A4;

        then (K * ( ||.t.|| * ||.s.||)) <= (K * 1) by A1, XREAL_1: 64;

        hence r <= K by A3, A5, XXREAL_0: 2;

      end;

    end

    theorem :: LOPBAN_9:13

    for X,Y,Z be RealNormSpace holds for g be BilinearOperator of X, Y, Z holds g is Lipschitzian iff ( PreNorms g) is bounded_above

    proof

      let X,Y,Z be RealNormSpace;

      let g be BilinearOperator of X, Y, Z;

      now

        reconsider K = ( upper_bound ( PreNorms g)) as Real;

        assume

         A1: ( PreNorms g) is bounded_above;

         A2:

        now

          let t be VECTOR of X, s be VECTOR of Y;

          now

            per cases ;

              case

               A3: t = ( 0. X) or s = ( 0. Y);

              then

               A4: ||.t.|| = 0 or ||.s.|| = 0 ;

              t = ( 0 * t) or s = ( 0 * s) by A3;

              

              then (g . (t,s)) = ( 0 * (g . (t,s))) by LOPBAN_8: 12

              .= ( 0. Z) by RLVECT_1: 10;

              hence ||.(g . (t,s)).|| <= ((K * ||.t.||) * ||.s.||) by A4;

            end;

              case

               A5: t <> ( 0. X) & s <> ( 0. Y);

              reconsider t1 = (( ||.t.|| " ) * t) as VECTOR of X;

              reconsider s1 = (( ||.s.|| " ) * s) as VECTOR of Y;

              

               A6: ||.t.|| <> 0 & ||.s.|| <> 0 by A5, NORMSP_0:def 5;

              then

               A7: ( ||.t.|| * ||.s.||) <> 0 by XCMPLX_1: 6;

              

               A8: (( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) * ( ||.t.|| * ||.s.||)) = (( ||.(g . (t,s)).|| * (( ||.t.|| * ||.s.||) " )) * ( ||.t.|| * ||.s.||)) by XCMPLX_0:def 9

              .= ( ||.(g . (t,s)).|| * ((( ||.t.|| * ||.s.||) " ) * ( ||.t.|| * ||.s.||)))

              .= ( ||.(g . (t,s)).|| * 1) by A7, XCMPLX_0:def 7

              .= ||.(g . (t,s)).||;

              

               A9: |.( ||.t.|| " ).| = |.(1 * ( ||.t.|| " )).|

              .= |.(1 / ||.t.||).| by XCMPLX_0:def 9

              .= (1 / ||.t.||) by ABSVALUE:def 1

              .= (1 * ( ||.t.|| " )) by XCMPLX_0:def 9

              .= ( ||.t.|| " );

              

               A10: |.( ||.s.|| " ).| = |.(1 * ( ||.s.|| " )).|

              .= |.(1 / ||.s.||).| by XCMPLX_0:def 9

              .= (1 / ||.s.||) by ABSVALUE:def 1

              .= (1 * ( ||.s.|| " )) by XCMPLX_0:def 9

              .= ( ||.s.|| " );

              

               A11: |.(( ||.t.|| * ||.s.||) " ).| = |.(( ||.t.|| " ) * ( ||.s.|| " )).| by XCMPLX_1: 204

              .= (( ||.t.|| " ) * ( ||.s.|| " )) by A9, A10, COMPLEX1: 65

              .= (( ||.t.|| * ||.s.||) " ) by XCMPLX_1: 204;

              

               A12: ||.t1.|| = ( |.( ||.t.|| " ).| * ||.t.||) by NORMSP_1:def 1

              .= 1 by A6, A9, XCMPLX_0:def 7;

               ||.s1.|| = ( |.( ||.s.|| " ).| * ||.s.||) by NORMSP_1:def 1

              .= 1 by A6, A10, XCMPLX_0:def 7;

              then

               A13: ||.(g . (t1,s1)).|| in { ||.(g . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 } by A12;

              ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) = ( ||.(g . (t,s)).|| * (( ||.t.|| * ||.s.||) " )) by XCMPLX_0:def 9

              .= ||.((( ||.t.|| * ||.s.||) " ) * (g . (t,s))).|| by A11, NORMSP_1:def 1

              .= ||.((( ||.t.|| " ) * ( ||.s.|| " )) * (g . (t,s))).|| by XCMPLX_1: 204

              .= ||.(( ||.t.|| " ) * (( ||.s.|| " ) * (g . (t,s)))).|| by RLVECT_1:def 7

              .= ||.(( ||.t.|| " ) * (g . (t,s1))).|| by LOPBAN_8: 12

              .= ||.(g . (t1,s1)).|| by LOPBAN_8: 12;

              then ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) <= K by A1, A13, SEQ_4:def 1;

              hence ||.(g . (t,s)).|| <= (K * ( ||.t.|| * ||.s.||)) by A8, XREAL_1: 64;

            end;

          end;

          hence ||.(g . (t,s)).|| <= ((K * ||.t.||) * ||.s.||);

        end;

        take K;

         0 <= K

        proof

          consider r0 be object such that

           A14: r0 in ( PreNorms g) by XBOOLE_0:def 1;

          reconsider r0 as Real by A14;

          now

            let r be Real;

            assume r in ( PreNorms g);

            then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(g . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

            hence 0 <= r;

          end;

          then 0 <= r0 by A14;

          hence thesis by A1, A14, SEQ_4:def 1;

        end;

        hence g is Lipschitzian by A2;

      end;

      hence thesis;

    end;

    definition

      let X,Y,Z be RealNormSpace;

      :: LOPBAN_9:def8

      func BoundedBilinearOperatorsNorm (X,Y,Z) -> Function of ( BoundedBilinearOperators (X,Y,Z)), REAL means

      : Def13: for x be object st x in ( BoundedBilinearOperators (X,Y,Z)) holds (it . x) = ( upper_bound ( PreNorms ( modetrans (x,X,Y,Z))));

      existence

      proof

        deffunc F( object) = ( upper_bound ( PreNorms ( modetrans ($1,X,Y,Z))));

        

         A1: for z be object st z in ( BoundedBilinearOperators (X,Y,Z)) holds F(z) in REAL by XREAL_0:def 1;

        thus ex f be Function of ( BoundedBilinearOperators (X,Y,Z)), REAL st for x be object st x in ( BoundedBilinearOperators (X,Y,Z)) holds (f . x) = F(x) from FUNCT_2:sch 2( A1);

      end;

      uniqueness

      proof

        let NORM1,NORM2 be Function of ( BoundedBilinearOperators (X,Y,Z)), REAL such that

         A2: for x be object st x in ( BoundedBilinearOperators (X,Y,Z)) holds (NORM1 . x) = ( upper_bound ( PreNorms ( modetrans (x,X,Y,Z)))) and

         A3: for x be object st x in ( BoundedBilinearOperators (X,Y,Z)) holds (NORM2 . x) = ( upper_bound ( PreNorms ( modetrans (x,X,Y,Z))));

        

         A4: for z be object st z in ( BoundedBilinearOperators (X,Y,Z)) holds (NORM1 . z) = (NORM2 . z)

        proof

          let z be object such that

           A5: z in ( BoundedBilinearOperators (X,Y,Z));

          (NORM1 . z) = ( upper_bound ( PreNorms ( modetrans (z,X,Y,Z)))) by A2, A5;

          hence thesis by A3, A5;

        end;

        ( dom NORM1) = ( BoundedBilinearOperators (X,Y,Z)) by FUNCT_2:def 1;

        hence thesis by A4, FUNCT_2:def 1;

      end;

    end

    

     Th29: for X,Y,Z be RealNormSpace holds for f be Lipschitzian BilinearOperator of X, Y, Z holds ( modetrans (f,X,Y,Z)) = f

    proof

      let X,Y,Z be RealNormSpace;

      let f be Lipschitzian BilinearOperator of X, Y, Z;

      f in ( BoundedBilinearOperators (X,Y,Z)) by Def9;

      hence thesis by Def11;

    end;

    registration

      let X,Y,Z be RealNormSpace;

      let f be Lipschitzian BilinearOperator of X, Y, Z;

      reduce ( modetrans (f,X,Y,Z)) to f;

      reducibility by Th29;

    end

    theorem :: LOPBAN_9:14

    

     Th30: for X,Y,Z be RealNormSpace holds for f be Lipschitzian BilinearOperator of X, Y, Z holds (( BoundedBilinearOperatorsNorm (X,Y,Z)) . f) = ( upper_bound ( PreNorms f))

    proof

      let X,Y,Z be RealNormSpace;

      let f be Lipschitzian BilinearOperator of X, Y, Z;

      reconsider f9 = f as set;

      f in ( BoundedBilinearOperators (X,Y,Z)) by Def9;

      

      hence (( BoundedBilinearOperatorsNorm (X,Y,Z)) . f) = ( upper_bound ( PreNorms ( modetrans (f9,X,Y,Z)))) by Def13

      .= ( upper_bound ( PreNorms f));

    end;

    definition

      let X,Y,Z be RealNormSpace;

      :: LOPBAN_9:def9

      func R_NormSpace_of_BoundedBilinearOperators (X,Y,Z) -> non empty NORMSTR equals NORMSTR (# ( BoundedBilinearOperators (X,Y,Z)), ( Zero_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))), ( Add_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))), ( Mult_ (( BoundedBilinearOperators (X,Y,Z)),( R_VectorSpace_of_BilinearOperators (X,Y,Z)))), ( BoundedBilinearOperatorsNorm (X,Y,Z)) #);

      coherence ;

    end

    theorem :: LOPBAN_9:15

    

     Th31: for X,Y,Z be RealNormSpace holds (the carrier of [:X, Y:] --> ( 0. Z)) = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)))

    proof

      let X,Y,Z be RealNormSpace;

      (the carrier of [:X, Y:] --> ( 0. Z)) = ( 0. ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z))) by Th26

      .= ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)));

      hence thesis;

    end;

    theorem :: LOPBAN_9:16

    

     Th32: for X,Y,Z be RealNormSpace holds for f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds for g be Lipschitzian BilinearOperator of X, Y, Z st g = f holds for t be VECTOR of X, s be VECTOR of Y holds ||.(g . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||)

    proof

      let X,Y,Z be RealNormSpace;

      let f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      let g be Lipschitzian BilinearOperator of X, Y, Z such that

       A1: g = f;

      now

        let t be VECTOR of X, s be VECTOR of Y;

        now

          per cases ;

            case

             A3: t = ( 0. X) or s = ( 0. Y);

            then

             A4: ||.t.|| = 0 or ||.s.|| = 0 ;

            t = ( 0 * t) or s = ( 0 * s) by A3;

            

            then (g . (t,s)) = ( 0 * (g . (t,s))) by LOPBAN_8: 12

            .= ( 0. Z) by RLVECT_1: 10;

            hence ||.(g . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||) by A4;

          end;

            case

             A5: t <> ( 0. X) & s <> ( 0. Y);

            reconsider t1 = (( ||.t.|| " ) * t) as VECTOR of X;

            reconsider s1 = (( ||.s.|| " ) * s) as VECTOR of Y;

            

             A6: ||.t.|| <> 0 & ||.s.|| <> 0 by A5, NORMSP_0:def 5;

            then

             A7: ( ||.t.|| * ||.s.||) <> 0 by XCMPLX_1: 6;

            

             A8: |.( ||.t.|| " ).| = |.(1 * ( ||.t.|| " )).|

            .= |.(1 / ||.t.||).| by XCMPLX_0:def 9

            .= (1 / ||.t.||) by ABSVALUE:def 1

            .= (1 * ( ||.t.|| " )) by XCMPLX_0:def 9

            .= ( ||.t.|| " );

            

             A9: |.( ||.s.|| " ).| = |.(1 * ( ||.s.|| " )).|

            .= |.(1 / ||.s.||).| by XCMPLX_0:def 9

            .= (1 / ||.s.||) by ABSVALUE:def 1

            .= (1 * ( ||.s.|| " )) by XCMPLX_0:def 9

            .= ( ||.s.|| " );

            

             A10: |.(( ||.t.|| * ||.s.||) " ).| = |.(( ||.t.|| " ) * ( ||.s.|| " )).| by XCMPLX_1: 204

            .= (( ||.t.|| " ) * ( ||.s.|| " )) by A8, A9, COMPLEX1: 65

            .= (( ||.t.|| * ||.s.||) " ) by XCMPLX_1: 204;

            

             A11: ||.t1.|| = ( |.( ||.t.|| " ).| * ||.t.||) by NORMSP_1:def 1

            .= 1 by A6, A8, XCMPLX_0:def 7;

            

             A12: ||.s1.|| = ( |.( ||.s.|| " ).| * ||.s.||) by NORMSP_1:def 1

            .= 1 by A6, A9, XCMPLX_0:def 7;

            ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) = ( ||.(g . (t,s)).|| * (( ||.t.|| * ||.s.||) " )) by XCMPLX_0:def 9

            .= ||.((( ||.t.|| * ||.s.||) " ) * (g . (t,s))).|| by A10, NORMSP_1:def 1

            .= ||.((( ||.t.|| " ) * ( ||.s.|| " )) * (g . (t,s))).|| by XCMPLX_1: 204

            .= ||.(( ||.t.|| " ) * (( ||.s.|| " ) * (g . (t,s)))).|| by RLVECT_1:def 7

            .= ||.(( ||.t.|| " ) * (g . (t,s1))).|| by LOPBAN_8: 12

            .= ||.(g . (t1,s1)).|| by LOPBAN_8: 12;

            then ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) in { ||.(g . (t,s)).|| where t be VECTOR of X, s be VECTOR of Y : ||.t.|| <= 1 & ||.s.|| <= 1 } by A11, A12;

            then ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) <= ( upper_bound ( PreNorms g)) by SEQ_4:def 1;

            then

             A13: ( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) <= ||.f.|| by A1, Th30;

            (( ||.(g . (t,s)).|| / ( ||.t.|| * ||.s.||)) * ( ||.t.|| * ||.s.||)) = (( ||.(g . (t,s)).|| * (( ||.t.|| * ||.s.||) " )) * ( ||.t.|| * ||.s.||)) by XCMPLX_0:def 9

            .= ( ||.(g . (t,s)).|| * ((( ||.t.|| * ||.s.||) " ) * ( ||.t.|| * ||.s.||)))

            .= ( ||.(g . (t,s)).|| * 1) by A7, XCMPLX_0:def 7

            .= ||.(g . (t,s)).||;

            hence ||.(g . (t,s)).|| <= ( ||.f.|| * ( ||.t.|| * ||.s.||)) by A13, XREAL_1: 64;

          end;

        end;

        hence ||.(g . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||);

      end;

      hence thesis;

    end;

    theorem :: LOPBAN_9:17

    

     Th33: for X,Y,Z be RealNormSpace holds for f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds 0 <= ||.f.||

    proof

      let X,Y,Z be RealNormSpace;

      let f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      reconsider g = f as Lipschitzian BilinearOperator of X, Y, Z by Def9;

      consider r0 be object such that

       A1: r0 in ( PreNorms g) by XBOOLE_0:def 1;

      reconsider r0 as Real by A1;

      

       A3: (( BoundedBilinearOperatorsNorm (X,Y,Z)) . f) = ( upper_bound ( PreNorms g)) by Th30;

      now

        let r be Real;

        assume r in ( PreNorms g);

        then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(g . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

        hence 0 <= r;

      end;

      then 0 <= r0 by A1;

      hence thesis by A1, A3, SEQ_4:def 1;

    end;

    theorem :: LOPBAN_9:18

    

     Th34: for X,Y,Z be RealNormSpace holds for f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) st f = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z))) holds 0 = ||.f.||

    proof

      let X,Y,Z be RealNormSpace;

      let f be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) such that

       A1: f = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)));

      reconsider g = f as Lipschitzian BilinearOperator of X, Y, Z by Def9;

      set z = (the carrier of [:X, Y:] --> ( 0. Z));

      reconsider z as Function of the carrier of [:X, Y:], the carrier of Z;

      consider r0 be object such that

       A2: r0 in ( PreNorms g) by XBOOLE_0:def 1;

      reconsider r0 as Real by A2;

      

       A3: (for s be Real st s in ( PreNorms g) holds s <= 0 ) implies ( upper_bound ( PreNorms g)) <= 0 by SEQ_4: 45;

      

       A5: z = g by A1, Th31;

       A6:

      now

        let r be Real;

        assume r in ( PreNorms g);

        then

        consider t be VECTOR of X, s be VECTOR of Y such that

         A7: r = ||.(g . (t,s)).|| and ||.t.|| <= 1 & ||.s.|| <= 1;

         [t, s] is Point of [:X, Y:] by LMELM2;

        then (g . (t,s)) = ( 0. Z) by FUNCOP_1: 7, A5;

        hence 0 <= r & r <= 0 by A7;

      end;

      then 0 <= r0 by A2;

      then ( upper_bound ( PreNorms g)) = 0 by A6, A2, A3, SEQ_4:def 1;

      hence thesis by Th30;

    end;

    registration

      let X,Y,Z be RealNormSpace;

      cluster -> Function-like Relation-like for Element of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      coherence ;

    end

    definition

      let X,Y,Z be RealNormSpace;

      let f be Element of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      let v be VECTOR of X, w be VECTOR of Y;

      :: original: .

      redefine

      func f . (v,w) -> VECTOR of Z ;

      coherence

      proof

        reconsider f as BilinearOperator of X, Y, Z by Def9;

        (f . (v,w)) is VECTOR of Z;

        hence thesis;

      end;

    end

    theorem :: LOPBAN_9:19

    

     Th35: for X,Y,Z be RealNormSpace holds for f,g,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds h = (f + g) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) + (g . (x,y)))

    proof

      let X,Y,Z be RealNormSpace;

      let f,g,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      reconsider f1 = f, g1 = g, h1 = h as VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      h = (f + g) iff h1 = (f1 + g1);

      hence thesis by Th24;

    end;

    theorem :: LOPBAN_9:20

    

     Th36: for X,Y,Z be RealNormSpace holds for f,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds for a be Real holds h = (a * f) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = (a * (f . (x,y)))

    proof

      let X,Y,Z be RealNormSpace;

      let f,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      let a be Real;

      reconsider f1 = f as VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      reconsider h1 = h as VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

      h = (a * f) iff h1 = (a * f1);

      hence thesis by Th25;

    end;

    theorem :: LOPBAN_9:21

    

     Th37: for X,Y,Z be RealNormSpace holds for f,g be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds for a be Real holds ( ||.f.|| = 0 iff f = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)))) & ||.(a * f).|| = ( |.a.| * ||.f.||) & ||.(f + g).|| <= ( ||.f.|| + ||.g.||)

    proof

      let X,Y,Z be RealNormSpace;

      let f,g be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      let a be Real;

       A1:

      now

        assume

         A2: f = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)));

        thus ||.f.|| = 0

        proof

          reconsider g = f as Lipschitzian BilinearOperator of X, Y, Z by Def9;

          set z = (the carrier of [:X, Y:] --> ( 0. Z));

          reconsider z as Function of the carrier of [:X, Y:], the carrier of Z;

          consider r0 be object such that

           A3: r0 in ( PreNorms g) by XBOOLE_0:def 1;

          reconsider r0 as Real by A3;

          

           A4: (for s be Real st s in ( PreNorms g) holds s <= 0 ) implies ( upper_bound ( PreNorms g)) <= 0 by SEQ_4: 45;

          

           A6: z = g by A2, Th31;

           A7:

          now

            let r be Real;

            assume r in ( PreNorms g);

            then

            consider t be VECTOR of X, s be VECTOR of Y such that

             A8: r = ||.(g . (t,s)).|| and ||.t.|| <= 1 & ||.s.|| <= 1;

             [t, s] is Point of [:X, Y:] by LMELM2;

            then (g . (t,s)) = ( 0. Z) by A6, FUNCOP_1: 7;

            hence 0 <= r & r <= 0 by A8;

          end;

          then 0 <= r0 by A3;

          then ( upper_bound ( PreNorms g)) = 0 by A3, A4, A7, SEQ_4:def 1;

          hence thesis by Th30;

        end;

      end;

      

       A9: ||.(f + g).|| <= ( ||.f.|| + ||.g.||)

      proof

        reconsider f1 = f, g1 = g, h1 = (f + g) as Lipschitzian BilinearOperator of X, Y, Z by Def9;

        

         A10: (for s be Real st s in ( PreNorms h1) holds s <= ( ||.f.|| + ||.g.||)) implies ( upper_bound ( PreNorms h1)) <= ( ||.f.|| + ||.g.||) by SEQ_4: 45;

         A11:

        now

          let t be VECTOR of X, s be VECTOR of Y such that

           A12: ||.t.|| <= 1 & ||.s.|| <= 1;

          

           A13: ( ||.t.|| * ||.s.||) <= (1 * 1) by A12, XREAL_1: 66;

           0 <= ||.g.|| by Th33;

          then

           A14: ( ||.g.|| * ( ||.t.|| * ||.s.||)) <= ( ||.g.|| * 1) by A13, XREAL_1: 64;

           0 <= ||.f.|| by Th33;

          then ( ||.f.|| * ( ||.t.|| * ||.s.||)) <= ( ||.f.|| * 1) by A13, XREAL_1: 64;

          then

           A15: ((( ||.f.|| * ||.t.||) * ||.s.||) + (( ||.g.|| * ||.t.||) * ||.s.||)) <= (( ||.f.|| * 1) + ( ||.g.|| * 1)) by A14, XREAL_1: 7;

          

           A16: ||.((f1 . (t,s)) + (g1 . (t,s))).|| <= ( ||.(f1 . (t,s)).|| + ||.(g1 . (t,s)).||) by NORMSP_1:def 1;

          

           A17: ||.(g1 . (t,s)).|| <= (( ||.g.|| * ||.t.||) * ||.s.||) by Th32;

           ||.(f1 . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||) by Th32;

          then ( ||.(f1 . (t,s)).|| + ||.(g1 . (t,s)).||) <= ((( ||.f.|| * ||.t.||) * ||.s.||) + (( ||.g.|| * ||.t.||) * ||.s.||)) by A17, XREAL_1: 7;

          then

           A18: ( ||.(f1 . (t,s)).|| + ||.(g1 . (t,s)).||) <= ( ||.f.|| + ||.g.||) by A15, XXREAL_0: 2;

           ||.(h1 . (t,s)).|| = ||.((f1 . (t,s)) + (g1 . (t,s))).|| by Th35;

          hence ||.(h1 . (t,s)).|| <= ( ||.f.|| + ||.g.||) by A16, A18, XXREAL_0: 2;

        end;

        now

          let r be Real;

          assume r in ( PreNorms h1);

          then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(h1 . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

          hence r <= ( ||.f.|| + ||.g.||) by A11;

        end;

        hence thesis by A10, Th30;

      end;

      

       A20: ||.(a * f).|| = ( |.a.| * ||.f.||)

      proof

        reconsider f1 = f, h1 = (a * f) as Lipschitzian BilinearOperator of X, Y, Z by Def9;

        

         A21: (for s be Real st s in ( PreNorms h1) holds s <= ( |.a.| * ||.f.||)) implies ( upper_bound ( PreNorms h1)) <= ( |.a.| * ||.f.||) by SEQ_4: 45;

         A22:

        now

          

           A23: 0 <= ||.f.|| by Th33;

          let t be VECTOR of X, s be VECTOR of Y;

          assume ||.t.|| <= 1 & ||.s.|| <= 1;

          then ( ||.t.|| * ||.s.||) <= (1 * 1) by XREAL_1: 66;

          then

           A24: ( ||.f.|| * ( ||.t.|| * ||.s.||)) <= ( ||.f.|| * 1) by A23, XREAL_1: 64;

           ||.(f1 . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||) by Th32;

          then

           A25: ||.(f1 . (t,s)).|| <= ||.f.|| by A24, XXREAL_0: 2;

          

           A26: ||.(a * (f1 . (t,s))).|| = ( |.a.| * ||.(f1 . (t,s)).||) by NORMSP_1:def 1;

          

           A27: 0 <= |.a.| by COMPLEX1: 46;

           ||.(h1 . (t,s)).|| = ||.(a * (f1 . (t,s))).|| by Th36;

          hence ||.(h1 . (t,s)).|| <= ( |.a.| * ||.f.||) by A25, A26, A27, XREAL_1: 64;

        end;

         A28:

        now

          let r be Real;

          assume r in ( PreNorms h1);

          then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(h1 . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

          hence r <= ( |.a.| * ||.f.||) by A22;

        end;

         A29:

        now

          per cases ;

            case

             A30: a <> 0 ;

             A31:

            now

              

               A32: 0 <= ||.(a * f).|| by Th33;

              let t be VECTOR of X, s be VECTOR of Y;

              assume ||.t.|| <= 1 & ||.s.|| <= 1;

              then ( ||.t.|| * ||.s.||) <= (1 * 1) by XREAL_1: 66;

              then

               A33: ( ||.(a * f).|| * ( ||.t.|| * ||.s.||)) <= ( ||.(a * f).|| * 1) by A32, XREAL_1: 64;

               ||.(h1 . (t,s)).|| <= (( ||.(a * f).|| * ||.t.||) * ||.s.||) by Th32;

              then

               A34: ||.(h1 . (t,s)).|| <= ||.(a * f).|| by A33, XXREAL_0: 2;

              (h1 . (t,s)) = (a * (f1 . (t,s))) by Th36;

              

              then

               A35: ((a " ) * (h1 . (t,s))) = (((a " ) * a) * (f1 . (t,s))) by RLVECT_1:def 7

              .= (1 * (f1 . (t,s))) by A30, XCMPLX_0:def 7

              .= (f1 . (t,s)) by RLVECT_1:def 8;

              

               A36: |.(a " ).| = |.(1 * (a " )).|

              .= |.(1 / a).| by XCMPLX_0:def 9

              .= (1 / |.a.|) by ABSVALUE: 7

              .= (1 * ( |.a.| " )) by XCMPLX_0:def 9

              .= ( |.a.| " );

              

               A37: 0 <= |.(a " ).| by COMPLEX1: 46;

               ||.((a " ) * (h1 . (t,s))).|| = ( |.(a " ).| * ||.(h1 . (t,s)).||) by NORMSP_1:def 1;

              hence ||.(f1 . (t,s)).|| <= (( |.a.| " ) * ||.(a * f).||) by A34, A35, A36, A37, XREAL_1: 64;

            end;

             A38:

            now

              let r be Real;

              assume r in ( PreNorms f1);

              then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(f1 . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

              hence r <= (( |.a.| " ) * ||.(a * f).||) by A31;

            end;

            

             A39: (for s be Real st s in ( PreNorms f1) holds s <= (( |.a.| " ) * ||.(a * f).||)) implies ( upper_bound ( PreNorms f1)) <= (( |.a.| " ) * ||.(a * f).||) by SEQ_4: 45;

            

             A40: 0 <= |.a.| by COMPLEX1: 46;

             ||.f.|| <= (( |.a.| " ) * ||.(a * f).||) by A38, A39, Th30;

            then ( |.a.| * ||.f.||) <= ( |.a.| * (( |.a.| " ) * ||.(a * f).||)) by A40, XREAL_1: 64;

            then

             A41: ( |.a.| * ||.f.||) <= (( |.a.| * ( |.a.| " )) * ||.(a * f).||);

             |.a.| <> 0 by A30, COMPLEX1: 47;

            then ( |.a.| * ||.f.||) <= (1 * ||.(a * f).||) by A41, XCMPLX_0:def 7;

            hence ( |.a.| * ||.f.||) <= ||.(a * f).||;

          end;

            case

             A42: a = 0 ;

            reconsider fz = f as VECTOR of ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z));

            

             A43: (a * f) = (a * fz)

            .= ( 0. ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z))) by A42, RLVECT_1: 10

            .= ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)));

            

            thus ( |.a.| * ||.f.||) = ( 0 * ||.f.||) by A42, ABSVALUE: 2

            .= ||.(a * f).|| by A43, Th34;

          end;

        end;

         ||.(a * f).|| <= ( |.a.| * ||.f.||) by A21, A28, Th30;

        hence thesis by A29, XXREAL_0: 1;

      end;

      now

        reconsider g = f as Lipschitzian BilinearOperator of X, Y, Z by Def9;

        set z = (the carrier of [:X, Y:] --> ( 0. Z));

        reconsider z as Function of the carrier of [:X, Y:], the carrier of Z;

        assume

         A44: ||.f.|| = 0 ;

        now

          let t be VECTOR of X, s be VECTOR of Y;

          

           A45: [t, s] is Point of [:X, Y:] by LMELM2;

           ||.(g . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||) by Th32;

          then ||.(g . (t,s)).|| = 0 by A44;

          

          hence (g . (t,s)) = ( 0. Z) by NORMSP_0:def 5

          .= (z . (t,s)) by A45, FUNCOP_1: 7;

        end;

        then g = z by BINOP_1: 2;

        hence f = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z))) by Th31;

      end;

      hence thesis by A1, A9, A20;

    end;

    

     Th38: for X,Y,Z be RealNormSpace holds ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) is reflexive discerning RealNormSpace-like

    proof

      let X,Y,Z be RealNormSpace;

      thus ||.( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z))).|| = 0 by Th37;

      for x,y be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds for a be Real holds ( ||.x.|| = 0 iff x = ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)))) & ||.(a * x).|| = ( |.a.| * ||.x.||) & ||.(x + y).|| <= ( ||.x.|| + ||.y.||) by Th37;

      hence thesis by NORMSP_1:def 1, NORMSP_0:def 5;

    end;

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) -> non empty;

      coherence ;

    end

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) -> reflexive discerning RealNormSpace-like;

      coherence by Th38;

    end

    theorem :: LOPBAN_9:22

    

     Th39: for X,Y,Z be RealNormSpace holds ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) is RealNormSpace

    proof

      let X,Y,Z be RealNormSpace;

      ( R_VectorSpace_of_BoundedBilinearOperators (X,Y,Z)) is RealLinearSpace;

      hence thesis by RSSPACE3: 2;

    end;

    registration

      let X,Y,Z be RealNormSpace;

      cluster ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) -> vector-distributive scalar-distributive scalar-associative scalar-unital Abelian add-associative right_zeroed right_complementable;

      coherence by Th39;

    end

    theorem :: LOPBAN_9:23

    

     Th40: for X,Y,Z be RealNormSpace holds for f,g,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) holds h = (f - g) iff for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) - (g . (x,y)))

    proof

      let X,Y,Z be RealNormSpace;

      let f,g,h be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      reconsider f9 = f, g9 = g, h9 = h as Lipschitzian BilinearOperator of X, Y, Z by Def9;

      hereby

        assume h = (f - g);

        then (h + g) = (f - (g - g)) by RLVECT_1: 29;

        then

         A1: (h + g) = (f - ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)))) by RLVECT_1: 15;

        now

          let x be VECTOR of X, y be VECTOR of Y;

          (f9 . (x,y)) = ((h9 . (x,y)) + (g9 . (x,y))) by A1, Th35;

          then ((f9 . (x,y)) - (g9 . (x,y))) = ((h9 . (x,y)) + ((g9 . (x,y)) - (g9 . (x,y)))) by RLVECT_1:def 3;

          then ((f9 . (x,y)) - (g9 . (x,y))) = ((h9 . (x,y)) + ( 0. Z)) by RLVECT_1: 15;

          hence ((f9 . (x,y)) - (g9 . (x,y))) = (h9 . (x,y));

        end;

        hence for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) - (g . (x,y)));

      end;

      assume

       A2: for x be VECTOR of X, y be VECTOR of Y holds (h . (x,y)) = ((f . (x,y)) - (g . (x,y)));

      now

        let x be VECTOR of X, y be VECTOR of Y;

        (h9 . (x,y)) = ((f9 . (x,y)) - (g9 . (x,y))) by A2;

        then ((h9 . (x,y)) + (g9 . (x,y))) = ((f9 . (x,y)) - ((g9 . (x,y)) - (g9 . (x,y)))) by RLVECT_1: 29;

        then ((h9 . (x,y)) + (g9 . (x,y))) = ((f9 . (x,y)) - ( 0. Z)) by RLVECT_1: 15;

        hence ((h9 . (x,y)) + (g9 . (x,y))) = (f9 . (x,y));

      end;

      then f = (h + g) by Th35;

      then (f - g) = (h + (g - g)) by RLVECT_1:def 3;

      then (f - g) = (h + ( 0. ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)))) by RLVECT_1: 15;

      hence thesis;

    end;

    begin

    

     Lm3: for e be Real, seq be Real_Sequence st (seq is convergent & ex k be Nat st for i be Nat st k <= i holds (seq . i) <= e) holds ( lim seq) <= e

    proof

      let e be Real;

      let seq be Real_Sequence such that

       A1: seq is convergent and

       A2: ex k be Nat st for i be Nat st k <= i holds (seq . i) <= e;

      consider k be Nat such that

       A3: for i be Nat st k <= i holds (seq . i) <= e by A2;

      reconsider ee = e as Element of REAL by XREAL_0:def 1;

      set cseq = ( seq_const e);

      

       A4: ( lim cseq) = (cseq . 1) by SEQ_4: 26

      .= e by SEQ_1: 57;

       A5:

      now

        let i be Nat;

        

         A6: ((seq ^\ k) . i) = (seq . (k + i)) by NAT_1:def 3;

        (seq . (k + i)) <= e by A3, NAT_1: 11;

        hence ((seq ^\ k) . i) <= (cseq . i) by A6, SEQ_1: 57;

      end;

      ( lim (seq ^\ k)) = ( lim seq) by A1, SEQ_4: 20;

      hence thesis by A1, A5, A4, SEQ_2: 18;

    end;

    theorem :: LOPBAN_9:24

    

     Th42: for X,Y,Z be RealNormSpace st Z is complete holds for seq be sequence of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) st seq is Cauchy_sequence_by_Norm holds seq is convergent

    proof

      let X,Y,Z be RealNormSpace such that

       A1: Z is complete;

      let vseq be sequence of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) such that

       A2: vseq is Cauchy_sequence_by_Norm;

      defpred P[ set, set] means ex xseq be sequence of Z st (for n be Nat holds (xseq . n) = ((vseq . n) . $1)) & xseq is convergent & $2 = ( lim xseq);

      

       A3: for xy be Element of [:X, Y:] holds ex z be Element of Z st P[xy, z]

      proof

        let xy be Element of [:X, Y:];

        deffunc F( Nat) = (( modetrans ((vseq . $1),X,Y,Z)) . xy);

        consider xseq be sequence of Z such that

         A4: for n be Element of NAT holds (xseq . n) = F(n) from FUNCT_2:sch 4;

        

         A5: for n be Nat holds (xseq . n) = ((vseq . n) . xy)

        proof

          let n be Nat;

          n in NAT by ORDINAL1:def 12;

          then

           A6: (xseq . n) = (( modetrans ((vseq . n),X,Y,Z)) . xy) by A4;

          (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

          hence thesis by A6;

        end;

        take ( lim xseq);

        consider x be Point of X, y be Point of Y such that

         A7: xy = [x, y] by PRVECT_3: 18;

        

         A8: for m,k be Nat holds ||.((xseq . m) - (xseq . k)).|| <= ( ||.((vseq . m) - (vseq . k)).|| * ( ||.x.|| * ||.y.||))

        proof

          let m,k be Nat;

          reconsider h1 = ((vseq . m) - (vseq . k)) as Lipschitzian BilinearOperator of X, Y, Z by Def9;

          

           A9: (xseq . m) = ((vseq . m) . (x,y)) by A5, A7;

          

           A10: (xseq . k) = ((vseq . k) . (x,y)) by A5, A7;

          ((xseq . m) - (xseq . k)) = (h1 . (x,y)) by A9, A10, Th40;

          then ||.((xseq . m) - (xseq . k)).|| <= (( ||.((vseq . m) - (vseq . k)).|| * ||.x.||) * ||.y.||) by Th32;

          hence thesis;

        end;

        now

          let e be Real such that

           A11: e > 0 ;

          now

            per cases ;

              case

               A12: x = ( 0. X) or y = ( 0. Y);

              reconsider k = 0 as Nat;

              take k;

              thus for n,m be Nat st n >= k & m >= k holds ||.((xseq . n) - (xseq . m)).|| < e

              proof

                let n,m be Nat such that n >= k and m >= k;

                

                 A13: (xseq . m) = ((vseq . m) . (x,y)) by A5, A7;

                

                 A14: (vseq . m) is Lipschitzian BilinearOperator of X, Y, Z & (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

                

                 A15: x = ( 0 * x) or y = ( 0 * y) by A12;

                

                then

                 A16: ((vseq . m) . (x,y)) = ( 0 * ((vseq . m) . (x,y))) by A14, LOPBAN_8: 12

                .= ( 0. Z) by RLVECT_1: 10;

                

                 A17: (xseq . n) = ((vseq . n) . (x,y)) by A5, A7;

                ((vseq . n) . (x,y)) = ( 0 * ((vseq . n) . (x,y))) by A14, A15, LOPBAN_8: 12

                .= ( 0. Z) by RLVECT_1: 10;

                hence thesis by A11, A13, A16, A17;

              end;

            end;

              case x <> ( 0. X) & y <> ( 0. Y);

              then ||.x.|| <> 0 & ||.y.|| <> 0 by NORMSP_0:def 5;

              then ||.x.|| > 0 & ||.y.|| > 0 ;

              then

               A18: 0 < ( ||.x.|| * ||.y.||) by XREAL_1: 129;

              then

              consider k be Nat such that

               A19: for n,m be Nat st n >= k & m >= k holds ||.((vseq . n) - (vseq . m)).|| < (e / ( ||.x.|| * ||.y.||)) by A2, A11, XREAL_1: 139, RSSPACE3: 8;

              take k;

              thus for n,m be Nat st n >= k & m >= k holds ||.((xseq . n) - (xseq . m)).|| < e

              proof

                let n,m be Nat such that

                 A20: n >= k and

                 A21: m >= k;

                 ||.((vseq . n) - (vseq . m)).|| < (e / ( ||.x.|| * ||.y.||)) by A19, A20, A21;

                then

                 A22: ( ||.((vseq . n) - (vseq . m)).|| * ( ||.x.|| * ||.y.||)) < ((e / ( ||.x.|| * ||.y.||)) * ( ||.x.|| * ||.y.||)) by A18, XREAL_1: 68;

                

                 A23: ((e / ( ||.x.|| * ||.y.||)) * ( ||.x.|| * ||.y.||)) = ((e * (( ||.x.|| * ||.y.||) " )) * ( ||.x.|| * ||.y.||)) by XCMPLX_0:def 9

                .= (e * ((( ||.x.|| * ||.y.||) " ) * ( ||.x.|| * ||.y.||)))

                .= (e * 1) by A18, XCMPLX_0:def 7

                .= e;

                 ||.((xseq . n) - (xseq . m)).|| <= ( ||.((vseq . n) - (vseq . m)).|| * ( ||.x.|| * ||.y.||)) by A8;

                hence thesis by A22, A23, XXREAL_0: 2;

              end;

            end;

          end;

          hence ex k be Nat st for n,m be Nat st n >= k & m >= k holds ||.((xseq . n) - (xseq . m)).|| < e;

        end;

        then xseq is convergent by A1, RSSPACE3: 8;

        hence thesis by A5;

      end;

      consider f be Function of the carrier of [:X, Y:], the carrier of Z such that

       A24: for z be Element of [:X, Y:] holds P[z, (f . z)] from FUNCT_2:sch 3( A3);

      reconsider tseq = f as Function of [:X, Y:], Z;

      

       A25: for x1,x2 be Point of X, y be Point of Y holds (tseq . ((x1 + x2),y)) = ((tseq . (x1,y)) + (tseq . (x2,y)))

      proof

        let x1,x2 be Point of X, y be Point of Y;

        reconsider x1y = [x1, y] as Point of [:X, Y:] by LMELM2;

        reconsider x2y = [x2, y] as Point of [:X, Y:] by LMELM2;

        reconsider x1x2y = [(x1 + x2), y] as Point of [:X, Y:] by LMELM2;

        consider sqx1y be sequence of Z such that

         A26: for n be Nat holds (sqx1y . n) = ((vseq . n) . x1y) & sqx1y is convergent & (tseq . x1y) = ( lim sqx1y) by A24;

        consider sqx2y be sequence of Z such that

         A27: for n be Nat holds (sqx2y . n) = ((vseq . n) . x2y) & sqx2y is convergent & (tseq . x2y) = ( lim sqx2y) by A24;

        consider sqx1x2y be sequence of Z such that

         A28: for n be Nat holds (sqx1x2y . n) = ((vseq . n) . x1x2y) & sqx1x2y is convergent & (tseq . x1x2y) = ( lim sqx1x2y) by A24;

        for n be Nat holds (sqx1x2y . n) = ((sqx1y . n) + (sqx2y . n))

        proof

          let n be Nat;

          

           A29: (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

          

           A30: (sqx1y . n) = ((vseq . n) . (x1,y)) by A26;

          

           A31: (sqx2y . n) = ((vseq . n) . (x2,y)) by A27;

          

          thus (sqx1x2y . n) = ((vseq . n) . ((x1 + x2),y)) by A28

          .= ((sqx1y . n) + (sqx2y . n)) by A29, A30, A31, LOPBAN_8: 12;

        end;

        then

         A32: sqx1x2y = (sqx1y + sqx2y) by NORMSP_1:def 2;

        thus (tseq . ((x1 + x2),y)) = ((tseq . (x1,y)) + (tseq . (x2,y))) by A26, A27, A28, A32, NORMSP_1: 25;

      end;

      

       A33: for x be Point of X, y be Point of Y, a be Real holds (tseq . ((a * x),y)) = (a * (tseq . (x,y)))

      proof

        let x be Point of X, y be Point of Y, a be Real;

        reconsider xy = [x, y] as Point of [:X, Y:] by LMELM2;

        reconsider axy = [(a * x), y] as Point of [:X, Y:] by LMELM2;

        consider sqxy be sequence of Z such that

         A34: for n be Nat holds (sqxy . n) = ((vseq . n) . xy) & sqxy is convergent & (tseq . xy) = ( lim sqxy) by A24;

        consider sqaxy be sequence of Z such that

         A35: for n be Nat holds (sqaxy . n) = ((vseq . n) . axy) & sqaxy is convergent & (tseq . axy) = ( lim sqaxy) by A24;

        for n be Nat holds (sqaxy . n) = (a * (sqxy . n))

        proof

          let n be Nat;

          

           A36: (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

          (sqaxy . n) = ((vseq . n) . ((a * x),y)) by A35

          .= (a * ((vseq . n) . (x,y))) by A36, LOPBAN_8: 12;

          hence (sqaxy . n) = (a * (sqxy . n)) by A34;

        end;

        then sqaxy = (a * sqxy) by NORMSP_1:def 5;

        hence (tseq . ((a * x),y)) = (a * (tseq . (x,y))) by A34, A35, NORMSP_1: 28;

      end;

      

       A40: for x be Point of X, y1,y2 be Point of Y holds (tseq . (x,(y1 + y2))) = ((tseq . (x,y1)) + (tseq . (x,y2)))

      proof

        let x be Point of X, y1,y2 be Point of Y;

        reconsider x1y = [x, y1] as Point of [:X, Y:] by LMELM2;

        reconsider x2y = [x, y2] as Point of [:X, Y:] by LMELM2;

        reconsider x1x2y = [x, (y1 + y2)] as Point of [:X, Y:] by LMELM2;

        consider sqx1y be sequence of Z such that

         A41: for n be Nat holds (sqx1y . n) = ((vseq . n) . x1y) & sqx1y is convergent & (tseq . x1y) = ( lim sqx1y) by A24;

        consider sqx2y be sequence of Z such that

         A42: for n be Nat holds (sqx2y . n) = ((vseq . n) . x2y) & sqx2y is convergent & (tseq . x2y) = ( lim sqx2y) by A24;

        consider sqx1x2y be sequence of Z such that

         A43: for n be Nat holds (sqx1x2y . n) = ((vseq . n) . x1x2y) & sqx1x2y is convergent & (tseq . x1x2y) = ( lim sqx1x2y) by A24;

        for n be Nat holds (sqx1x2y . n) = ((sqx1y . n) + (sqx2y . n))

        proof

          let n be Nat;

          

           A44: (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

          

           A45: (sqx1y . n) = ((vseq . n) . (x,y1)) by A41;

          

           A46: (sqx2y . n) = ((vseq . n) . (x,y2)) by A42;

          

          thus (sqx1x2y . n) = ((vseq . n) . (x,(y1 + y2))) by A43

          .= ((sqx1y . n) + (sqx2y . n)) by A44, A45, A46, LOPBAN_8: 12;

        end;

        then sqx1x2y = (sqx1y + sqx2y) by NORMSP_1:def 2;

        hence (tseq . (x,(y1 + y2))) = ((tseq . (x,y1)) + (tseq . (x,y2))) by A41, A42, A43, NORMSP_1: 25;

      end;

      for x be Point of X, y be Point of Y, a be Real holds (tseq . (x,(a * y))) = (a * (tseq . (x,y)))

      proof

        let x be Point of X, y be Point of Y, a be Real;

        reconsider xy = [x, y] as Point of [:X, Y:] by LMELM2;

        reconsider axy = [x, (a * y)] as Point of [:X, Y:] by LMELM2;

        consider sqxy be sequence of Z such that

         A48: for n be Nat holds (sqxy . n) = ((vseq . n) . xy) & sqxy is convergent & (tseq . xy) = ( lim sqxy) by A24;

        consider sqaxy be sequence of Z such that

         A49: for n be Nat holds (sqaxy . n) = ((vseq . n) . axy) & sqaxy is convergent & (tseq . axy) = ( lim sqaxy) by A24;

        for n be Nat holds (sqaxy . n) = (a * (sqxy . n))

        proof

          let n be Nat;

          

           A50: (vseq . n) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

          (sqaxy . n) = ((vseq . n) . (x,(a * y))) by A49

          .= (a * ((vseq . n) . (x,y))) by A50, LOPBAN_8: 12;

          hence (sqaxy . n) = (a * (sqxy . n)) by A48;

        end;

        then sqaxy = (a * sqxy) by NORMSP_1:def 5;

        hence (tseq . (x,(a * y))) = (a * (tseq . (x,y))) by A48, A49, NORMSP_1: 28;

      end;

      then

      reconsider tseq as BilinearOperator of X, Y, Z by A25, A33, A40, LOPBAN_8: 12;

       B53:

      now

        let e1 be Real such that

         A54: e1 > 0 ;

        reconsider e = e1 as Real;

        consider k be Nat such that

         A55: for n,m be Nat st n >= k & m >= k holds ||.((vseq . n) - (vseq . m)).|| < e by A2, A54, RSSPACE3: 8;

        reconsider k as Nat;

        take k;

        now

          let m be Nat;

          assume m >= k;

          then

           A56: ||.((vseq . m) - (vseq . k)).|| < e by A55;

          

           A57: ||.(vseq . m).|| = ( ||.vseq.|| . m) by NORMSP_0:def 4;

          

           A58: ||.(vseq . k).|| = ( ||.vseq.|| . k) by NORMSP_0:def 4;

           |.( ||.(vseq . m).|| - ||.(vseq . k).||).| <= ||.((vseq . m) - (vseq . k)).|| by NORMSP_1: 9;

          hence |.(( ||.vseq.|| . m) - ( ||.vseq.|| . k)).| < e1 by A56, A57, A58, XXREAL_0: 2;

        end;

        hence for m be Nat st m >= k holds |.(( ||.vseq.|| . m) - ( ||.vseq.|| . k)).| < e1;

      end;

      then

       A59: ||.vseq.|| is convergent by SEQ_4: 41;

      

       A60: tseq is Lipschitzian

      proof

        take ( lim ||.vseq.||);

         A61:

        now

          let x be Point of X, y be Point of Y;

           [x, y] is set by TARSKI: 1;

          then

          reconsider xy = [x, y] as Point of [:X, Y:] by PRVECT_3: 18;

          consider xyseq be sequence of Z such that

           A62: for n be Nat holds (xyseq . n) = ((vseq . n) . xy) and

           A63: xyseq is convergent and

           A64: (tseq . xy) = ( lim xyseq) by A24;

          

           A65: ||.(tseq . xy).|| = ( lim ||.xyseq.||) by A63, A64, LOPBAN_1: 20;

          

           A66: for m be Nat holds ||.(xyseq . m).|| <= ( ||.(vseq . m).|| * ( ||.x.|| * ||.y.||))

          proof

            let m be Nat;

            (vseq . m) is Lipschitzian BilinearOperator of X, Y, Z by Def9;

            then ||.((vseq . m) . (x,y)).|| <= (( ||.(vseq . m).|| * ||.x.||) * ||.y.||) by Th32;

            hence ||.(xyseq . m).|| <= ( ||.(vseq . m).|| * ( ||.x.|| * ||.y.||)) by A62;

          end;

          

           A68: for n be Nat holds ( ||.xyseq.|| . n) <= ((( ||.x.|| * ||.y.||) (#) ||.vseq.||) . n)

          proof

            let n be Nat;

            

             A69: ( ||.xyseq.|| . n) = ||.(xyseq . n).|| by NORMSP_0:def 4;

            

             A70: ||.(vseq . n).|| = ( ||.vseq.|| . n) by NORMSP_0:def 4;

             ||.(xyseq . n).|| <= ( ||.(vseq . n).|| * ( ||.x.|| * ||.y.||)) by A66;

            hence thesis by A69, A70, SEQ_1: 9;

          end;

          

           A72: ( lim (( ||.x.|| * ||.y.||) (#) ||.vseq.||)) = (( lim ||.vseq.||) * ( ||.x.|| * ||.y.||)) by B53, SEQ_2: 8, SEQ_4: 41;

           ||.xyseq.|| is convergent by A63, A64, LOPBAN_1: 20;

          hence ||.(tseq . (x,y)).|| <= ((( lim ||.vseq.||) * ||.x.||) * ||.y.||) by A59, A65, A68, A72, SEQ_2: 18;

        end;

        now

          let n be Nat;

           ||.(vseq . n).|| >= 0 ;

          hence ( ||.vseq.|| . n) >= 0 by NORMSP_0:def 4;

        end;

        hence thesis by B53, A61, SEQ_2: 17, SEQ_4: 41;

      end;

      

       A73: for e be Real st e > 0 holds ex k be Nat st for n be Nat st n >= k holds for x be Point of X, y be Point of Y holds ||.(((vseq . n) . (x,y)) - (tseq . (x,y))).|| <= ((e * ||.x.||) * ||.y.||)

      proof

        let e be Real;

        assume e > 0 ;

        then

        consider k be Nat such that

         A74: for n,m be Nat st n >= k & m >= k holds ||.((vseq . n) - (vseq . m)).|| < e by A2, RSSPACE3: 8;

        take k;

        now

          let n be Nat such that

           A75: n >= k;

          now

            let x be Point of X, y be Point of Y;

             [x, y] is set by TARSKI: 1;

            then

            reconsider xy = [x, y] as Point of [:X, Y:] by PRVECT_3: 18;

            consider xyseq be sequence of Z such that

             A76: for n be Nat holds (xyseq . n) = ((vseq . n) . xy) and

             A77: xyseq is convergent and

             A78: (tseq . xy) = ( lim xyseq) by A24;

            

             A79: for m,k be Nat holds ||.((xyseq . m) - (xyseq . k)).|| <= ( ||.((vseq . m) - (vseq . k)).|| * ( ||.x.|| * ||.y.||))

            proof

              let m,k be Nat;

              reconsider h1 = ((vseq . m) - (vseq . k)) as Lipschitzian BilinearOperator of X, Y, Z by Def9;

              (xyseq . k) = ((vseq . k) . xy) by A76;

              

              then ((xyseq . m) - (xyseq . k)) = (((vseq . m) . (x,y)) - ((vseq . k) . (x,y))) by A76

              .= (h1 . (x,y)) by Th40;

              then ||.((xyseq . m) - (xyseq . k)).|| <= (( ||.((vseq . m) - (vseq . k)).|| * ||.x.||) * ||.y.||) by Th32;

              hence thesis;

            end;

            

             A81: for m be Nat st m >= k holds ||.((xyseq . n) - (xyseq . m)).|| <= ((e * ||.x.||) * ||.y.||)

            proof

              let m be Nat;

              assume m >= k;

              then

               A82: ||.((vseq . n) - (vseq . m)).|| < e by A74, A75;

              

               A83: ||.((xyseq . n) - (xyseq . m)).|| <= ( ||.((vseq . n) - (vseq . m)).|| * ( ||.x.|| * ||.y.||)) by A79;

              ( ||.((vseq . n) - (vseq . m)).|| * ( ||.x.|| * ||.y.||)) <= (e * ( ||.x.|| * ||.y.||)) by A82, XREAL_1: 64;

              hence thesis by A83, XXREAL_0: 2;

            end;

             ||.((xyseq . n) - (tseq . (x,y))).|| <= ((e * ||.x.||) * ||.y.||)

            proof

              deffunc F( Nat) = ||.((xyseq . $1) - (xyseq . n)).||;

              consider rseq be Real_Sequence such that

               A84: for m be Nat holds (rseq . m) = F(m) from SEQ_1:sch 1;

              now

                let i be object;

                assume i in NAT ;

                then

                reconsider k = i as Nat;

                

                thus (rseq . i) = ||.((xyseq . k) - (xyseq . n)).|| by A84

                .= ||.((xyseq - (xyseq . n)) . k).|| by NORMSP_1:def 4

                .= ( ||.(xyseq - (xyseq . n)).|| . i) by NORMSP_0:def 4;

              end;

              then

               A85: rseq = ||.(xyseq - (xyseq . n)).|| by FUNCT_2: 12;

              

               A86: (xyseq - (xyseq . n)) is convergent by A77, NORMSP_1: 21;

              ( lim (xyseq - (xyseq . n))) = ((tseq . (x,y)) - (xyseq . n)) by A77, A78, NORMSP_1: 27;

              then

               A87: ( lim rseq) = ||.((tseq . (x,y)) - (xyseq . n)).|| by A85, A86, LOPBAN_1: 41;

              for m be Nat st m >= k holds (rseq . m) <= ((e * ||.x.||) * ||.y.||)

              proof

                let m be Nat such that

                 A88: m >= k;

                (rseq . m) = ||.((xyseq . m) - (xyseq . n)).|| by A84

                .= ||.((xyseq . n) - (xyseq . m)).|| by NORMSP_1: 7;

                hence thesis by A81, A88;

              end;

              then ( lim rseq) <= ((e * ||.x.||) * ||.y.||) by A85, A86, LOPBAN_1: 41, Lm3;

              hence thesis by A87, NORMSP_1: 7;

            end;

            hence ||.(((vseq . n) . (x,y)) - (tseq . (x,y))).|| <= ((e * ||.x.||) * ||.y.||) by A76;

          end;

          hence for x be Point of X, y be Point of Y holds ||.(((vseq . n) . (x,y)) - (tseq . (x,y))).|| <= ((e * ||.x.||) * ||.y.||);

        end;

        hence thesis;

      end;

      reconsider tseq as Lipschitzian BilinearOperator of X, Y, Z by A60;

      reconsider tv = tseq as Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) by Def9;

      

       A89: for e be Real st e > 0 holds ex k be Nat st for n be Nat st n >= k holds ||.((vseq . n) - tv).|| <= e

      proof

        let e be Real such that

         A90: e > 0 ;

        consider k be Nat such that

         A91: for n be Nat st n >= k holds for x be Point of X, y be Point of Y holds ||.(((vseq . n) . (x,y)) - (tseq . (x,y))).|| <= ((e * ||.x.||) * ||.y.||) by A73, A90;

        now

          set g1 = tseq;

          let n be Nat such that

           A92: n >= k;

          reconsider h1 = ((vseq . n) - tv) as Lipschitzian BilinearOperator of X, Y, Z by Def9;

          set f1 = (vseq . n);

           A93:

          now

            let t be Point of X, s be Point of Y;

            assume ||.t.|| <= 1 & ||.s.|| <= 1;

            then ( ||.t.|| * ||.s.||) <= (1 * 1) by XREAL_1: 66;

            then

             A94: (e * ( ||.t.|| * ||.s.||)) <= (e * 1) by A90, XREAL_1: 64;

            

             A95: ||.((f1 . (t,s)) - (g1 . (t,s))).|| <= ((e * ||.t.||) * ||.s.||) by A91, A92;

             ||.(h1 . (t,s)).|| = ||.((f1 . (t,s)) - (g1 . (t,s))).|| by Th40;

            hence ||.(h1 . (t,s)).|| <= e by A94, A95, XXREAL_0: 2;

          end;

           A96:

          now

            let r be Real;

            assume r in ( PreNorms h1);

            then ex t be VECTOR of X, s be VECTOR of Y st r = ||.(h1 . (t,s)).|| & ||.t.|| <= 1 & ||.s.|| <= 1;

            hence r <= e by A93;

          end;

          (for s be Real st s in ( PreNorms h1) holds s <= e) implies ( upper_bound ( PreNorms h1)) <= e by SEQ_4: 45;

          hence ||.((vseq . n) - tv).|| <= e by A96, Th30;

        end;

        hence thesis;

      end;

      for e be Real st e > 0 holds ex m be Nat st for n be Nat st n >= m holds ||.((vseq . n) - tv).|| < e

      proof

        let e be Real such that

         A98: e > 0 ;

        consider m be Nat such that

         A99: for n be Nat st n >= m holds ||.((vseq . n) - tv).|| <= (e / 2) by A89, A98, XREAL_1: 215;

        

         A100: (e / 2) < e by A98, XREAL_1: 216;

        now

          let n be Nat;

          assume n >= m;

          then ||.((vseq . n) - tv).|| <= (e / 2) by A99;

          hence ||.((vseq . n) - tv).|| < e by A100, XXREAL_0: 2;

        end;

        hence thesis;

      end;

      hence thesis by NORMSP_1:def 6;

    end;

    theorem :: LOPBAN_9:25

    

     Th43: for X,Y be RealNormSpace, Z be RealBanachSpace holds ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) is RealBanachSpace

    proof

      let X,Y be RealNormSpace;

      let Z be RealBanachSpace;

      for seq be sequence of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) st seq is Cauchy_sequence_by_Norm holds seq is convergent by Th42;

      hence thesis by LOPBAN_1:def 15;

    end;

    registration

      let X,Y be RealNormSpace;

      let Z be RealBanachSpace;

      cluster ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) -> complete;

      coherence by Th43;

    end

    begin

    reserve X,Y,Z for RealLinearSpace;

    theorem :: LOPBAN_9:26

    ex I be LinearOperator of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z)))), ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) st I is bijective & for u be Point of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z)))) holds for x be Point of X, y be Point of Y holds ((I . u) . (x,y)) = ((u . x) . y)

    proof

      set XC = the carrier of X;

      set YC = the carrier of Y;

      set ZC = the carrier of Z;

      consider I0 be Function of ( Funcs (XC,( Funcs (YC,ZC)))), ( Funcs ( [:XC, YC:],ZC)) such that

       A1: I0 is bijective & for f be Function of XC, ( Funcs (YC,ZC)) holds for d,e be object st d in XC & e in YC holds ((I0 . f) . (d,e)) = ((f . d) . e) by NDIFF_6: 1;

      set LXYZ = the carrier of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z))));

      set BXYZ = the carrier of ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

      set LYZ = the carrier of ( R_VectorSpace_of_LinearOperators (Y,Z));

      now

        let x be object;

        assume x in ( Funcs (XC,LYZ));

        then

        consider f be Function such that

         A5: x = f & ( dom f) = XC & ( rng f) c= LYZ by FUNCT_2:def 2;

        ( rng f) c= ( Funcs (YC,ZC)) by A5, XBOOLE_1: 1;

        hence x in ( Funcs (XC,( Funcs (YC,ZC)))) by A5, FUNCT_2:def 2;

      end;

      then

       A6: ( Funcs (XC,LYZ)) c= ( Funcs (XC,( Funcs (YC,ZC)))) by TARSKI:def 3;

      then LXYZ c= ( Funcs (XC,( Funcs (YC,ZC)))) by XBOOLE_1: 1;

      then

      reconsider I = (I0 | LXYZ) as Function of LXYZ, ( Funcs ( [:XC, YC:],ZC)) by FUNCT_2: 32;

      

       A7: for x be Element of LXYZ holds (for p be Point of X, q be Point of Y holds ex G be LinearOperator of Y, Z st G = (x . p) & ((I . x) . (p,q)) = (G . q)) & (I . x) in BXYZ

      proof

        let f be Element of LXYZ;

        

         A8: (I . f) = (I0 . f) by FUNCT_1: 49;

        

         A9: f in ( Funcs (XC,( Funcs (YC,ZC)))) by A6, TARSKI:def 3, XBOOLE_1: 1;

        then

         A10: f is Function of XC, ( Funcs (YC,ZC)) by FUNCT_2: 66;

        reconsider g = f as Function of XC, ( Funcs (YC,ZC)) by A9, FUNCT_2: 66;

        reconsider F = f as LinearOperator of X, ( R_VectorSpace_of_LinearOperators (Y,Z)) by LOPBAN_1:def 6;

        thus for x be Point of X, y be Point of Y holds ex G be LinearOperator of Y, Z st G = (f . x) & ((I . f) . (x,y)) = (G . y)

        proof

          let x be Point of X, y be Point of Y;

          (g . x) = (F . x);

          then

          reconsider G = (g . x) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          take G;

          thus thesis by A1, A8;

        end;

        reconsider BL = (I0 . f) as Function of [:X, Y:], Z by A9, FUNCT_2: 5, FUNCT_2: 66;

        

         A14: for x1,x2 be Point of X, y be Point of Y holds (BL . ((x1 + x2),y)) = ((BL . (x1,y)) + (BL . (x2,y)))

        proof

          let x1,x2 be Point of X, y be Point of Y;

          

           A15: (BL . (x1,y)) = ((F . x1) . y) by A1, A10;

          

           A16: (BL . (x2,y)) = ((F . x2) . y) by A1, A10;

          

           A17: (BL . ((x1 + x2),y)) = ((F . (x1 + x2)) . y) by A1, A10;

          (F . (x1 + x2)) = ((F . x1) + (F . x2)) by VECTSP_1:def 20;

          hence thesis by A15, A16, A17, LOPBAN_1: 16;

        end;

        

         A18: for x be Point of X, y be Point of Y, a be Real holds (BL . ((a * x),y)) = (a * (BL . (x,y)))

        proof

          let x be Point of X, y be Point of Y, a be Real;

          

           A19: (BL . ((a * x),y)) = ((F . (a * x)) . y) by A1, A10;

          

           A20: (BL . (x,y)) = ((F . x) . y) by A1, A10;

          (F . (a * x)) = (a * (F . x)) by LOPBAN_1:def 5;

          hence thesis by A19, A20, LOPBAN_1: 17;

        end;

        

         A21: for x be Point of X, y1,y2 be Point of Y holds (BL . (x,(y1 + y2))) = ((BL . (x,y1)) + (BL . (x,y2)))

        proof

          let x be Point of X, y1,y2 be Point of Y;

          reconsider Fx = (F . x) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          

           A22: (BL . (x,y1)) = (Fx . y1) by A1, A10;

          

           A23: (BL . (x,y2)) = (Fx . y2) by A1, A10;

          (BL . (x,(y1 + y2))) = (Fx . (y1 + y2)) by A1, A10;

          hence thesis by A22, A23, VECTSP_1:def 20;

        end;

        

         A25: for x be Point of X, y be Point of Y, a be Real holds (BL . (x,(a * y))) = (a * (BL . (x,y)))

        proof

          let x be Point of X, y be Point of Y, a be Real;

          reconsider Fx = (F . x) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          

           A26: (BL . (x,y)) = (Fx . y) by A1, A10;

          (BL . (x,(a * y))) = (Fx . (a * y)) by A1, A10;

          hence thesis by A26, LOPBAN_1:def 5;

        end;

        reconsider BL as BilinearOperator of X, Y, Z by A14, A18, A21, A25, LOPBAN_8: 11;

        BL in BXYZ by Def6;

        hence (I . f) in BXYZ by FUNCT_1: 49;

      end;

      then ( rng I) c= BXYZ by FUNCT_2: 114;

      then

      reconsider I as Function of LXYZ, BXYZ by FUNCT_2: 6;

      

       A28: for x1,x2 be Element of LXYZ holds (I . (x1 + x2)) = ((I . x1) + (I . x2))

      proof

        let x1,x2 be Element of LXYZ;

        for p be Point of X, q be Point of Y holds ((I . (x1 + x2)) . (p,q)) = (((I . x1) . (p,q)) + ((I . x2) . (p,q)))

        proof

          let p be Point of X, q be Point of Y;

          consider Gx1p be LinearOperator of Y, Z such that

           A29: Gx1p = (x1 . p) & ((I . x1) . (p,q)) = (Gx1p . q) by A7;

          consider Gx2p be LinearOperator of Y, Z such that

           A30: Gx2p = (x2 . p) & ((I . x2) . (p,q)) = (Gx2p . q) by A7;

          consider Gx1x2p be LinearOperator of Y, Z such that

           A31: Gx1x2p = ((x1 + x2) . p) & ((I . (x1 + x2)) . (p,q)) = (Gx1x2p . q) by A7;

          ((x1 + x2) . p) = ((x1 . p) + (x2 . p)) by LOPBAN_1: 16;

          hence thesis by A29, A30, A31, LOPBAN_1: 16;

        end;

        hence thesis by Th16;

      end;

      for x be Element of LXYZ, a be Real holds (I . (a * x)) = (a * (I . x))

      proof

        let x be Element of LXYZ, a be Real;

        for p be Point of X, q be Point of Y holds ((I . (a * x)) . (p,q)) = (a * ((I . x) . (p,q)))

        proof

          let p be Point of X, q be Point of Y;

          consider Gxp be LinearOperator of Y, Z such that

           A33: Gxp = (x . p) & ((I . x) . (p,q)) = (Gxp . q) by A7;

          consider Gxap be LinearOperator of Y, Z such that

           A34: Gxap = ((a * x) . p) & ((I . (a * x)) . (p,q)) = (Gxap . q) by A7;

          ((a * x) . p) = (a * (x . p)) by LOPBAN_1: 17;

          hence thesis by A33, A34, LOPBAN_1: 17;

        end;

        hence thesis by Th17;

      end;

      then

      reconsider I as LinearOperator of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z)))), ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by A28, LOPBAN_1:def 5, VECTSP_1:def 20;

      

       A36: for u be Point of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z)))) holds for x be Point of X, y be Point of Y holds ((I . u) . (x,y)) = ((u . x) . y)

      proof

        let u be Point of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z))));

        let p be Point of X, q be Point of Y;

        consider G be LinearOperator of Y, Z such that

         A37: G = (u . p) & ((I . u) . (p,q)) = (G . q) by A7;

        thus ((I . u) . (p,q)) = ((u . p) . q) by A37;

      end;

      for y be object st y in BXYZ holds ex x be object st x in LXYZ & y = (I . x)

      proof

        let y be object;

        assume

         A39: y in BXYZ;

        then y in ( Funcs ( [:XC, YC:],ZC));

        then y in ( rng I0) by A1, FUNCT_2:def 3;

        then

        consider f be object such that

         A40: f in ( Funcs (XC,( Funcs (YC,ZC)))) & (I0 . f) = y by FUNCT_2: 11;

        reconsider f as Function of XC, ( Funcs (YC,ZC)) by A40, FUNCT_2: 66;

        reconsider BL = y as BilinearOperator of X, Y, Z by A39, Def6;

        reconsider BLp = BL as Point of ( R_VectorSpace_of_BilinearOperators (X,Y,Z)) by Def6;

        

         A42: ( dom f) = XC by FUNCT_2:def 1;

        for x be object st x in XC holds (f . x) in LYZ

        proof

          let x be object;

          assume

           A43: x in XC;

          then

          reconsider fx = (f . x) as Function of YC, ZC by FUNCT_2: 5, FUNCT_2: 66;

          reconsider xp = x as Point of X by A43;

          

           A44: for p be Point of Y, q be Point of Y holds (fx . (p + q)) = ((fx . p) + (fx . q))

          proof

            let p be Point of Y, q be Point of Y;

            

             A45: (BL . (xp,p)) = (fx . p) by A1, A40;

            

             A46: (BL . (xp,q)) = (fx . q) by A1, A40;

            (BL . (xp,(p + q))) = (fx . (p + q)) by A1, A40;

            hence (fx . (p + q)) = ((fx . p) + (fx . q)) by A45, A46, LOPBAN_8: 11;

          end;

          for p be Point of Y, a be Real holds (fx . (a * p)) = (a * (fx . p))

          proof

            let p be Point of Y, a be Real;

            

             A48: (BL . (xp,p)) = (fx . p) by A1, A40;

            (BL . (xp,(a * p))) = (fx . (a * p)) by A1, A40;

            hence (fx . (a * p)) = (a * (fx . p)) by A48, LOPBAN_8: 11;

          end;

          then

          reconsider fx as LinearOperator of Y, Z by A44, LOPBAN_1:def 5, VECTSP_1:def 20;

          fx in LYZ by LOPBAN_1:def 6;

          hence (f . x) in LYZ;

        end;

        then

        reconsider f as Function of XC, LYZ by A42, FUNCT_2: 3;

        

         A50: for x1,x2 be Point of X holds (f . (x1 + x2)) = ((f . x1) + (f . x2))

        proof

          let x1,x2 be Point of X;

          reconsider fx1x2 = (f . (x1 + x2)) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          reconsider fx1 = (f . x1) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          reconsider fx2 = (f . x2) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          for y be Point of Y holds (fx1x2 . y) = ((fx1 . y) + (fx2 . y))

          proof

            let y be Point of Y;

            

             A51: (BL . (x1,y)) = (fx1 . y) by A1, A40;

            

             A52: (BL . (x2,y)) = (fx2 . y) by A1, A40;

            (BL . ((x1 + x2),y)) = (fx1x2 . y) by A1, A40;

            hence (fx1x2 . y) = ((fx1 . y) + (fx2 . y)) by A51, A52, LOPBAN_8: 11;

          end;

          hence (f . (x1 + x2)) = ((f . x1) + (f . x2)) by LOPBAN_1: 16;

        end;

        for x be Point of X, a be Real holds (f . (a * x)) = (a * (f . x))

        proof

          let x be Point of X, a be Real;

          reconsider fx = (f . x) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          reconsider fax = (f . (a * x)) as LinearOperator of Y, Z by LOPBAN_1:def 6;

          for y be Point of Y holds (fax . y) = (a * (fx . y))

          proof

            let y be Point of Y;

            

             A54: (BL . (x,y)) = (fx . y) by A1, A40;

            (BL . ((a * x),y)) = (fax . y) by A1, A40;

            hence (fax . y) = (a * (fx . y)) by A54, LOPBAN_8: 11;

          end;

          hence (f . (a * x)) = (a * (f . x)) by LOPBAN_1: 17;

        end;

        then

        reconsider f as LinearOperator of X, ( R_VectorSpace_of_LinearOperators (Y,Z)) by A50, LOPBAN_1:def 5, VECTSP_1:def 20;

        

         A56: f in LXYZ by LOPBAN_1:def 6;

        take f;

        thus thesis by A40, A56, FUNCT_1: 49;

      end;

      then

       A58: ( rng I) = BXYZ by FUNCT_2: 10;

      reconsider I as LinearOperator of ( R_VectorSpace_of_LinearOperators (X,( R_VectorSpace_of_LinearOperators (Y,Z)))), ( R_VectorSpace_of_BilinearOperators (X,Y,Z));

      take I;

      I is one-to-one onto by A1, A58, FUNCT_1: 52, FUNCT_2:def 3;

      hence thesis by A36;

    end;

    reserve X,Y,Z for RealNormSpace;

    theorem :: LOPBAN_9:27

    ex I be LinearOperator of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))), ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) st I is bijective & for u be Point of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))) holds ||.u.|| = ||.(I . u).|| & for x be Point of X, y be Point of Y holds ((I . u) . (x,y)) = ((u . x) . y)

    proof

      set XC = the carrier of X;

      set YC = the carrier of Y;

      set ZC = the carrier of Z;

      consider I0 be Function of ( Funcs (XC,( Funcs (YC,ZC)))), ( Funcs ( [:XC, YC:],ZC)) such that

       A1: I0 is bijective & for f be Function of XC, ( Funcs (YC,ZC)) holds for d,e be object st d in XC & e in YC holds ((I0 . f) . (d,e)) = ((f . d) . e) by NDIFF_6: 1;

      set LXYZ = the carrier of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z))));

      set BXYZ = the carrier of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z));

      set LYZ = the carrier of ( R_NormSpace_of_BoundedLinearOperators (Y,Z));

      

       A3: LYZ c= ( Funcs (YC,ZC)) by XBOOLE_1: 1;

      

       A4: LXYZ c= ( Funcs (XC,LYZ)) by XBOOLE_1: 1;

      ( Funcs (XC,LYZ)) c= ( Funcs (XC,( Funcs (YC,ZC))))

      proof

        let x be object;

        assume x in ( Funcs (XC,LYZ));

        then

        consider f be Function such that

         A6: x = f & ( dom f) = XC & ( rng f) c= LYZ by FUNCT_2:def 2;

        ( rng f) c= ( Funcs (YC,ZC)) by A3, A6, XBOOLE_1: 1;

        hence x in ( Funcs (XC,( Funcs (YC,ZC)))) by A6, FUNCT_2:def 2;

      end;

      then

       A7: LXYZ c= ( Funcs (XC,( Funcs (YC,ZC)))) by A4, XBOOLE_1: 1;

      then

      reconsider I = (I0 | LXYZ) as Function of LXYZ, ( Funcs ( [:XC, YC:],ZC)) by FUNCT_2: 32;

      

       A8: for x be Element of LXYZ holds (for p be Point of X, q be Point of Y holds ex G be Lipschitzian LinearOperator of Y, Z st G = (x . p) & ((I . x) . (p,q)) = (G . q)) & (I . x) is Lipschitzian BilinearOperator of X, Y, Z & (I . x) in BXYZ & ex Ix be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) st Ix = (I . x) & ||.x.|| = ||.Ix.||

      proof

        let f be Element of LXYZ;

        

         A9: (I . f) = (I0 . f) by FUNCT_1: 49;

        

         A10: f in ( Funcs (XC,( Funcs (YC,ZC)))) by A7, TARSKI:def 3;

        

         A11: f is Function of XC, ( Funcs (YC,ZC)) by A7, TARSKI:def 3, FUNCT_2: 66;

        reconsider g = f as Function of XC, ( Funcs (YC,ZC)) by A7, TARSKI:def 3, FUNCT_2: 66;

        reconsider F = f as Lipschitzian LinearOperator of X, ( R_NormSpace_of_BoundedLinearOperators (Y,Z)) by LOPBAN_1:def 9;

        thus for x be Point of X, y be Point of Y holds ex G be Lipschitzian LinearOperator of Y, Z st G = (f . x) & ((I . f) . (x,y)) = (G . y)

        proof

          let x be Point of X, y be Point of Y;

          (g . x) = (F . x);

          then

          reconsider G = (g . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          take G;

          thus thesis by A1, A9;

        end;

        reconsider BL = (I0 . f) as Function of [:X, Y:], Z by A10, FUNCT_2: 5, FUNCT_2: 66;

        

         A15: for x1,x2 be Point of X, y be Point of Y holds (BL . ((x1 + x2),y)) = ((BL . (x1,y)) + (BL . (x2,y)))

        proof

          let x1,x2 be Point of X, y be Point of Y;

          

           A16: (BL . (x1,y)) = ((F . x1) . y) by A1, A11;

          

           A17: (BL . (x2,y)) = ((F . x2) . y) by A1, A11;

          

           A18: (BL . ((x1 + x2),y)) = ((F . (x1 + x2)) . y) by A1, A11;

          (F . (x1 + x2)) = ((F . x1) + (F . x2)) by VECTSP_1:def 20;

          hence thesis by A16, A17, A18, LOPBAN_1: 35;

        end;

        

         A19: for x be Point of X, y be Point of Y, a be Real holds (BL . ((a * x),y)) = (a * (BL . (x,y)))

        proof

          let x be Point of X, y be Point of Y, a be Real;

          

           A20: (BL . ((a * x),y)) = ((F . (a * x)) . y) by A1, A11;

          

           A21: (BL . (x,y)) = ((F . x) . y) by A1, A11;

          (F . (a * x)) = (a * (F . x)) by LOPBAN_1:def 5;

          hence thesis by A20, A21, LOPBAN_1: 36;

        end;

        

         A22: for x be Point of X, y1,y2 be Point of Y holds (BL . (x,(y1 + y2))) = ((BL . (x,y1)) + (BL . (x,y2)))

        proof

          let x be Point of X, y1,y2 be Point of Y;

          reconsider Fx = (F . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          

           A23: (BL . (x,y1)) = (Fx . y1) by A1, A11;

          

           A24: (BL . (x,y2)) = (Fx . y2) by A1, A11;

          (BL . (x,(y1 + y2))) = (Fx . (y1 + y2)) by A1, A11;

          hence thesis by A23, A24, VECTSP_1:def 20;

        end;

        

         A26: for x be Point of X, y be Point of Y, a be Real holds (BL . (x,(a * y))) = (a * (BL . (x,y)))

        proof

          let x be Point of X, y be Point of Y, a be Real;

          reconsider Fx = (F . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          

           A27: (BL . (x,y)) = (Fx . y) by A1, A11;

          (BL . (x,(a * y))) = (Fx . (a * y)) by A1, A11;

          hence thesis by A27, LOPBAN_1:def 5;

        end;

        reconsider BL as BilinearOperator of X, Y, Z by A15, A19, A22, A26, LOPBAN_8: 12;

        

         A29: for x be Point of X, y be Point of Y holds ||.(BL . (x,y)).|| <= (( ||.f.|| * ||.x.||) * ||.y.||)

        proof

          let x be Point of X, y be Point of Y;

          reconsider Fx = (F . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          

           A30: (BL . (x,y)) = (Fx . y) by A1, A11;

          

           A31: ||.(Fx . y).|| <= ( ||.(F . x).|| * ||.y.||) by LOPBAN_1: 32;

          ( ||.(F . x).|| * ||.y.||) <= (( ||.f.|| * ||.x.||) * ||.y.||) by LOPBAN_1: 32, XREAL_1: 64;

          hence ||.(BL . (x,y)).|| <= (( ||.f.|| * ||.x.||) * ||.y.||) by A30, A31, XXREAL_0: 2;

        end;

        then

        reconsider BL as Lipschitzian BilinearOperator of X, Y, Z by Def8;

        reconsider BLp = BL as Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) by Def9;

        (I . f) = BL by FUNCT_1: 49;

        hence (I . f) is Lipschitzian BilinearOperator of X, Y, Z;

        BLp in BXYZ;

        hence (I . f) in BXYZ by FUNCT_1: 49;

        

         A33: ||.BLp.|| = ( upper_bound ( PreNorms ( modetrans (BL,X,Y,Z)))) by Def13

        .= ( upper_bound ( PreNorms BL));

        now

          let r be Real;

          assume r in ( PreNorms BL);

          then

          consider t be VECTOR of X, s be VECTOR of Y such that

           A34: r = ||.(BL . (t,s)).|| and

           A35: ||.t.|| <= 1 & ||.s.|| <= 1;

          

           A36: ||.(BL . (t,s)).|| <= (( ||.f.|| * ||.t.||) * ||.s.||) by A29;

          ( ||.t.|| * ||.s.||) <= (1 * 1) by A35, XREAL_1: 66;

          then ( ||.f.|| * ( ||.t.|| * ||.s.||)) <= ( ||.f.|| * 1) by XREAL_1: 64;

          hence r <= ||.f.|| by A34, A36, XXREAL_0: 2;

        end;

        then

         A37: ||.BLp.|| <= ||.f.|| by A33, SEQ_4: 45;

        

         A39: ||.f.|| = ( upper_bound ( PreNorms ( modetrans (F,X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))))) by LOPBAN_1:def 13

        .= ( upper_bound ( PreNorms F)) by LOPBAN_1: 29;

        now

          let r be Real;

          assume r in ( PreNorms F);

          then

          consider x be VECTOR of X such that

           A40: r = ||.(F . x).|| and

           A41: ||.x.|| <= 1;

          reconsider Fx = (F . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          

           A42: ||.(F . x).|| = ( upper_bound ( PreNorms Fx)) by LOPBAN_1: 30;

          now

            let s be Real;

            assume s in ( PreNorms Fx);

            then

            consider y be Point of Y such that

             B42: s = ||.(Fx . y).|| and

             A43: ||.y.|| <= 1;

            

             A44: ||.(Fx . y).|| = ||.(BL . (x,y)).|| by A1, A11;

            

             A45: ||.(BL . (x,y)).|| <= (( ||.BLp.|| * ||.x.||) * ||.y.||) by Th32;

            ( ||.x.|| * ||.y.||) <= (1 * 1) by A41, A43, XREAL_1: 66;

            then ( ||.BLp.|| * ( ||.x.|| * ||.y.||)) <= ( ||.BLp.|| * 1) by XREAL_1: 64;

            hence s <= ||.BLp.|| by B42, A44, A45, XXREAL_0: 2;

          end;

          hence r <= ||.BLp.|| by A40, A42, SEQ_4: 45;

        end;

        then

         A46: ||.f.|| <= ||.BLp.|| by A39, SEQ_4: 45;

        take BLp;

        thus BLp = (I . f) & ||.f.|| = ||.BLp.|| by A37, A46, FUNCT_1: 49, XXREAL_0: 1;

      end;

      then ( rng I) c= BXYZ by FUNCT_2: 114;

      then

      reconsider I as Function of LXYZ, BXYZ by FUNCT_2: 6;

      

       A47: for x1,x2 be Element of LXYZ holds (I . (x1 + x2)) = ((I . x1) + (I . x2))

      proof

        let x1,x2 be Element of LXYZ;

        for p be Point of X, q be Point of Y holds ((I . (x1 + x2)) . (p,q)) = (((I . x1) . (p,q)) + ((I . x2) . (p,q)))

        proof

          let p be Point of X, q be Point of Y;

          consider Gx1p be Lipschitzian LinearOperator of Y, Z such that

           A48: Gx1p = (x1 . p) & ((I . x1) . (p,q)) = (Gx1p . q) by A8;

          consider Gx2p be Lipschitzian LinearOperator of Y, Z such that

           A49: Gx2p = (x2 . p) & ((I . x2) . (p,q)) = (Gx2p . q) by A8;

          consider Gx1x2p be Lipschitzian LinearOperator of Y, Z such that

           A50: Gx1x2p = ((x1 + x2) . p) & ((I . (x1 + x2)) . (p,q)) = (Gx1x2p . q) by A8;

          ((x1 + x2) . p) = ((x1 . p) + (x2 . p)) by LOPBAN_1: 35;

          hence thesis by A48, A49, A50, LOPBAN_1: 35;

        end;

        hence thesis by Th35;

      end;

      for x be Element of LXYZ, a be Real holds (I . (a * x)) = (a * (I . x))

      proof

        let x be Element of LXYZ, a be Real;

        for p be Point of X, q be Point of Y holds ((I . (a * x)) . (p,q)) = (a * ((I . x) . (p,q)))

        proof

          let p be Point of X, q be Point of Y;

          consider Gxp be Lipschitzian LinearOperator of Y, Z such that

           A52: Gxp = (x . p) & ((I . x) . (p,q)) = (Gxp . q) by A8;

          consider Gxap be Lipschitzian LinearOperator of Y, Z such that

           A53: Gxap = ((a * x) . p) & ((I . (a * x)) . (p,q)) = (Gxap . q) by A8;

          ((a * x) . p) = (a * (x . p)) by LOPBAN_1: 36;

          hence thesis by A52, A53, LOPBAN_1: 36;

        end;

        hence thesis by Th36;

      end;

      then

      reconsider I as LinearOperator of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))), ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) by A47, LOPBAN_1:def 5, VECTSP_1:def 20;

      

       A55: for u be Point of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))) holds ||.u.|| = ||.(I . u).|| & for x be Point of X, y be Point of Y holds ((I . u) . (x,y)) = ((u . x) . y)

      proof

        let u be Point of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z))));

        consider Iu be Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) such that

         A56: Iu = (I . u) & ||.u.|| = ||.Iu.|| by A8;

        thus ||.u.|| = ||.(I . u).|| by A56;

        let p be Point of X, q be Point of Y;

        consider G be Lipschitzian LinearOperator of Y, Z such that

         A57: G = (u . p) & ((I . u) . (p,q)) = (G . q) by A8;

        thus ((I . u) . (p,q)) = ((u . p) . q) by A57;

      end;

      for y be object st y in BXYZ holds ex x be object st x in LXYZ & y = (I . x)

      proof

        let y be object;

        assume

         A59: y in BXYZ;

        then y in ( Funcs ( [:XC, YC:],ZC)) by TARSKI:def 3;

        then y in ( rng I0) by A1, FUNCT_2:def 3;

        then

        consider f be object such that

         A60: f in ( Funcs (XC,( Funcs (YC,ZC)))) & (I0 . f) = y by FUNCT_2: 11;

        reconsider f as Function of XC, ( Funcs (YC,ZC)) by A60, FUNCT_2: 66;

        reconsider BL = y as Lipschitzian BilinearOperator of X, Y, Z by A59, Def9;

        reconsider BLp = BL as Point of ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) by Def9;

        

         A62: ( dom f) = XC by FUNCT_2:def 1;

        for x be object st x in XC holds (f . x) in LYZ

        proof

          let x be object;

          assume

           A63: x in XC;

          then

          reconsider fx = (f . x) as Function of YC, ZC by FUNCT_2: 5, FUNCT_2: 66;

          reconsider xp = x as Point of X by A63;

          

           A64: for p be Point of Y, q be Point of Y holds (fx . (p + q)) = ((fx . p) + (fx . q))

          proof

            let p be Point of Y, q be Point of Y;

            

             A65: (BL . (xp,p)) = (fx . p) by A60, A1;

            

             A66: (BL . (xp,q)) = (fx . q) by A60, A1;

            (BL . (xp,(p + q))) = (fx . (p + q)) by A60, A1;

            hence (fx . (p + q)) = ((fx . p) + (fx . q)) by A65, A66, LOPBAN_8: 12;

          end;

          for p be Point of Y, a be Real holds (fx . (a * p)) = (a * (fx . p))

          proof

            let p be Point of Y, a be Real;

            

             A68: (BL . (xp,p)) = (fx . p) by A60, A1;

            (BL . (xp,(a * p))) = (fx . (a * p)) by A60, A1;

            hence (fx . (a * p)) = (a * (fx . p)) by A68, LOPBAN_8: 12;

          end;

          then

          reconsider fx as LinearOperator of Y, Z by A64, LOPBAN_1:def 5, VECTSP_1:def 20;

          for p be Point of Y holds ||.(fx . p).|| <= (( ||.BLp.|| * ||.xp.||) * ||.p.||)

          proof

            let p be Point of Y;

            (BL . (xp,p)) = (fx . p) by A60, A1;

            hence thesis by Th32;

          end;

          then

          reconsider fx as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 8;

          fx in LYZ by LOPBAN_1:def 9;

          hence (f . x) in LYZ;

        end;

        then

        reconsider f as Function of XC, LYZ by A62, FUNCT_2: 3;

        

         A71: for x1,x2 be Point of X holds (f . (x1 + x2)) = ((f . x1) + (f . x2))

        proof

          let x1,x2 be Point of X;

          reconsider fx1x2 = (f . (x1 + x2)) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          reconsider fx1 = (f . x1) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          reconsider fx2 = (f . x2) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          for y be Point of Y holds (fx1x2 . y) = ((fx1 . y) + (fx2 . y))

          proof

            let y be Point of Y;

            

             A72: (BL . (x1,y)) = (fx1 . y) by A60, A1;

            

             A73: (BL . (x2,y)) = (fx2 . y) by A60, A1;

            (BL . ((x1 + x2),y)) = (fx1x2 . y) by A60, A1;

            hence (fx1x2 . y) = ((fx1 . y) + (fx2 . y)) by A72, A73, LOPBAN_8: 12;

          end;

          hence (f . (x1 + x2)) = ((f . x1) + (f . x2)) by LOPBAN_1: 35;

        end;

        for x be Point of X, a be Real holds (f . (a * x)) = (a * (f . x))

        proof

          let x be Point of X, a be Real;

          reconsider fx = (f . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          reconsider fax = (f . (a * x)) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          for y be Point of Y holds (fax . y) = (a * (fx . y))

          proof

            let y be Point of Y;

            

             A75: (BL . (x,y)) = (fx . y) by A60, A1;

            (BL . ((a * x),y)) = (fax . y) by A60, A1;

            hence (fax . y) = (a * (fx . y)) by A75, LOPBAN_8: 12;

          end;

          hence (f . (a * x)) = (a * (f . x)) by LOPBAN_1: 36;

        end;

        then

        reconsider f as LinearOperator of X, ( R_NormSpace_of_BoundedLinearOperators (Y,Z)) by A71, LOPBAN_1:def 5, VECTSP_1:def 20;

        for x be Point of X holds ||.(f . x).|| <= ( ||.BLp.|| * ||.x.||)

        proof

          let x be Point of X;

          reconsider fx = (f . x) as Lipschitzian LinearOperator of Y, Z by LOPBAN_1:def 9;

          

           A78: for y be Point of Y holds ||.(fx . y).|| <= (( ||.BLp.|| * ||.x.||) * ||.y.||)

          proof

            let y be Point of Y;

            (BL . (x,y)) = (fx . y) by A60, A1;

            hence ||.(fx . y).|| <= (( ||.BLp.|| * ||.x.||) * ||.y.||) by Th32;

          end;

          

           A79: ||.(f . x).|| = ( upper_bound ( PreNorms fx)) by LOPBAN_1: 30;

          now

            let s be Real;

            assume s in ( PreNorms fx);

            then

            consider y be Point of Y such that

             A80: s = ||.(fx . y).|| and

             A81: ||.y.|| <= 1;

            

             A82: ||.(fx . y).|| <= (( ||.BLp.|| * ||.x.||) * ||.y.||) by A78;

            (( ||.BLp.|| * ||.x.||) * ||.y.||) <= (( ||.BLp.|| * ||.x.||) * 1) by A81, XREAL_1: 66;

            hence s <= ( ||.BLp.|| * ||.x.||) by A80, A82, XXREAL_0: 2;

          end;

          hence ||.(f . x).|| <= ( ||.BLp.|| * ||.x.||) by A79, SEQ_4: 45;

        end;

        then

        reconsider f as Lipschitzian LinearOperator of X, ( R_NormSpace_of_BoundedLinearOperators (Y,Z)) by LOPBAN_1:def 8;

        

         A83: f in LXYZ by LOPBAN_1:def 9;

        take f;

        thus thesis by A60, A83, FUNCT_1: 49;

      end;

      then

       A85: ( rng I) = BXYZ by FUNCT_2: 10;

      for u be Point of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))) holds ||.(I . u).|| <= (1 * ||.u.||) by A55;

      then

      reconsider I as Lipschitzian LinearOperator of ( R_NormSpace_of_BoundedLinearOperators (X,( R_NormSpace_of_BoundedLinearOperators (Y,Z)))), ( R_NormSpace_of_BoundedBilinearOperators (X,Y,Z)) by LOPBAN_1:def 8;

      take I;

      I is one-to-one onto by A1, A85, FUNCT_1: 52, FUNCT_2:def 3;

      hence thesis by A55;

    end;