let E, F, G be RealLinearSpace; :: thesis: for u being MultilinearOperator of <*E,F*>,G holds u * (IsoCPRLSP (E,F)) is BilinearOperator of E,F,G
let u be MultilinearOperator of <*E,F*>,G; :: thesis: u * (IsoCPRLSP (E,F)) is BilinearOperator of E,F,G
reconsider L = u * (IsoCPRLSP (E,F)) as Function of [:E,F:],G ;
dom <*E,F*> = Seg (len <*E,F*>) by FINSEQ_1:def 3;
then dom <*E,F*> = {1,2} by FINSEQ_1:2, FINSEQ_1:44;
then reconsider i1 = 1, i2 = 2 as Element of dom <*E,F*> by TARSKI:def 2;
A2: for x1, x2 being Point of E
for y being Point of F holds L . ((x1 + x2),y) = (L . (x1,y)) + (L . (x2,y))
proof
let x1, x2 be Point of E; :: thesis: for y being Point of F holds L . ((x1 + x2),y) = (L . (x1,y)) + (L . (x2,y))
let y be Point of F; :: thesis: L . ((x1 + x2),y) = (L . (x1,y)) + (L . (x2,y))
set x = x1;
reconsider xy = <*x1,y*> as Point of (product <*E,F*>) by PRVECT_3:14;
reconsider L1 = u * (reproj (i1,xy)) as LinearOperator of E,G by LOPBAN10:def 3;
A5: dom (reproj (i1,xy)) = the carrier of (<*E,F*> . i1) by FUNCT_2:def 1
.= the carrier of E ;
len xy = 2 by FINSEQ_1:44;
then dom xy = {1,2} by FINSEQ_1:2, FINSEQ_1:def 3;
then A7: i1 in dom xy by TARSKI:def 2;
then A14: (xy +* (i1,x1)) . 1 = x1 by FUNCT_7:31;
A8: len (xy +* (i1,(x1 + x2))) = 2 by LemmaA;
A9: (xy +* (i1,(x1 + x2))) . 1 = x1 + x2 by A7, FUNCT_7:31;
A10: (xy +* (i1,(x1 + x2))) . 2 = xy . i2 by FUNCT_7:32
.= y ;
reconsider x1x2 = x1 + x2 as Element of (<*E,F*> . i1) ;
A12: (reproj (i1,xy)) . x1x2 = xy +* (i1,(x1 + x2)) by NDIFF5def4
.= <*(x1 + x2),y*> by A8, A9, A10, FINSEQ_1:44 ;
A13: len (xy +* (i1,x1)) = 2 by LemmaA;
A15: (xy +* (i1,x1)) . 2 = xy . i2 by FUNCT_7:32
.= y ;
A17: (reproj (i1,xy)) . x1 = xy +* (i1,x1) by NDIFF5def4
.= <*x1,y*> by A13, A14, A15, FINSEQ_1:44 ;
A18: len (xy +* (i1,x2)) = 2 by LemmaA;
A19: (xy +* (i1,x2)) . 1 = x2 by A7, FUNCT_7:31;
A20: (xy +* (i1,x2)) . 2 = xy . i2 by FUNCT_7:32
.= y ;
A22: (reproj (i1,xy)) . x2 = xy +* (i1,x2) by NDIFF5def4
.= <*x2,y*> by A18, A19, A20, FINSEQ_1:44 ;
A4: ( [(x1 + x2),y] is Point of [:E,F:] & [x1,y] is Point of [:E,F:] & [x2,y] is Point of [:E,F:] ) ;
then A23: L . ((x1 + x2),y) = u . ((IsoCPRLSP (E,F)) . ((x1 + x2),y)) by FUNCT_2:15
.= u . ((reproj (i1,xy)) . (x1 + x2)) by A12, defISO
.= L1 . (x1 + x2) by A5, FUNCT_1:13 ;
A24: L . (x1,y) = u . ((IsoCPRLSP (E,F)) . (x1,y)) by A4, FUNCT_2:15
.= u . ((reproj (i1,xy)) . x1) by A17, defISO
.= L1 . x1 by A5, FUNCT_1:13 ;
L . (x2,y) = u . ((IsoCPRLSP (E,F)) . (x2,y)) by A4, FUNCT_2:15
.= u . ((reproj (i1,xy)) . x2) by A22, defISO
.= L1 . x2 by A5, FUNCT_1:13 ;
hence L . ((x1 + x2),y) = (L . (x1,y)) + (L . (x2,y)) by A23, A24, VECTSP_1:def 20; :: thesis: verum
end;
A26: for x being Point of E
for y being Point of F
for a being Real holds L . ((a * x),y) = a * (L . (x,y))
proof
let x be Point of E; :: thesis: for y being Point of F
for a being Real holds L . ((a * x),y) = a * (L . (x,y))

let y be Point of F; :: thesis: for a being Real holds L . ((a * x),y) = a * (L . (x,y))
let a be Real; :: thesis: L . ((a * x),y) = a * (L . (x,y))
reconsider xy = <*x,y*> as Point of (product <*E,F*>) by PRVECT_3:14;
reconsider L1 = u * (reproj (i1,xy)) as LinearOperator of E,G by LOPBAN10:def 3;
A29: dom (reproj (i1,xy)) = the carrier of (<*E,F*> . i1) by FUNCT_2:def 1
.= the carrier of E ;
len xy = 2 by FINSEQ_1:44;
then dom xy = {1,2} by FINSEQ_1:2, FINSEQ_1:def 3;
then A31: i1 in dom xy by TARSKI:def 2;
A32: len (xy +* (i1,(a * x))) = 2 by LemmaA;
A33: (xy +* (i1,(a * x))) . 1 = a * x by A31, FUNCT_7:31;
A34: (xy +* (i1,(a * x))) . 2 = xy . i2 by FUNCT_7:32
.= y ;
reconsider x1x2 = a * x as Element of (<*E,F*> . i1) ;
A36: (reproj (i1,xy)) . x1x2 = xy +* (i1,(a * x)) by NDIFF5def4
.= <*(a * x),y*> by A32, A33, A34, FINSEQ_1:44 ;
A37: len (xy +* (i1,x)) = 2 by LemmaA;
A38: (xy +* (i1,x)) . 1 = x by A31, FUNCT_7:31;
A39: (xy +* (i1,x)) . 2 = xy . i2 by FUNCT_7:32
.= y ;
A41: (reproj (i1,xy)) . x = xy +* (i1,x) by NDIFF5def4
.= <*x,y*> by A37, A38, A39, FINSEQ_1:44 ;
A28: ( [x,y] is Point of [:E,F:] & [(a * x),y] is Point of [:E,F:] ) ;
then A42: L . ((a * x),y) = u . ((IsoCPRLSP (E,F)) . ((a * x),y)) by FUNCT_2:15
.= u . ((reproj (i1,xy)) . (a * x)) by A36, defISO
.= L1 . (a * x) by A29, FUNCT_1:13 ;
L . (x,y) = u . ((IsoCPRLSP (E,F)) . (x,y)) by A28, FUNCT_2:15
.= u . ((reproj (i1,xy)) . x) by A41, defISO
.= L1 . x by A29, FUNCT_1:13 ;
hence L . ((a * x),y) = a * (L . (x,y)) by A42, LOPBAN_1:def 5; :: thesis: verum
end;
A44: for x being Point of E
for y1, y2 being Point of F holds L . (x,(y1 + y2)) = (L . (x,y1)) + (L . (x,y2))
proof
let x be Point of E; :: thesis: for y1, y2 being Point of F holds L . (x,(y1 + y2)) = (L . (x,y1)) + (L . (x,y2))
let y1, y2 be Point of F; :: thesis: L . (x,(y1 + y2)) = (L . (x,y1)) + (L . (x,y2))
reconsider xy = <*x,y1*> as Point of (product <*E,F*>) by PRVECT_3:14;
reconsider L1 = u * (reproj (i2,xy)) as LinearOperator of F,G by LOPBAN10:def 3;
A47: dom (reproj (i2,xy)) = the carrier of (<*E,F*> . i2) by FUNCT_2:def 1
.= the carrier of F ;
len xy = 2 by FINSEQ_1:44;
then dom xy = {1,2} by FINSEQ_1:2, FINSEQ_1:def 3;
then A49: i2 in dom xy by TARSKI:def 2;
A50: len (xy +* (i2,(y1 + y2))) = 2 by LemmaA;
A51: (xy +* (i2,(y1 + y2))) . 1 = xy . i1 by FUNCT_7:32
.= x ;
A52: (xy +* (i2,(y1 + y2))) . 2 = y1 + y2 by A49, FUNCT_7:31;
reconsider x1x2 = y1 + y2 as Element of (<*E,F*> . i2) ;
A54: (reproj (i2,xy)) . x1x2 = xy +* (i2,(y1 + y2)) by NDIFF5def4
.= <*x,(y1 + y2)*> by A50, A51, A52, FINSEQ_1:44 ;
A55: len (xy +* (i2,y1)) = 2 by LemmaA;
A56: (xy +* (i2,y1)) . 1 = xy . i1 by FUNCT_7:32
.= x ;
A57: (xy +* (i2,y1)) . 2 = y1 by A49, FUNCT_7:31;
A59: (reproj (i2,xy)) . y1 = xy +* (i2,y1) by NDIFF5def4
.= <*x,y1*> by A55, A56, A57, FINSEQ_1:44 ;
A60: len (xy +* (i2,y2)) = 2 by LemmaA;
A61: (xy +* (i2,y2)) . 1 = xy . i1 by FUNCT_7:32
.= x ;
A62: (xy +* (i2,y2)) . 2 = y2 by A49, FUNCT_7:31;
A64: (reproj (i2,xy)) . y2 = xy +* (i2,y2) by NDIFF5def4
.= <*x,y2*> by A60, A61, A62, FINSEQ_1:44 ;
A46: ( [x,(y1 + y2)] is Point of [:E,F:] & [x,y1] is Point of [:E,F:] & [x,y2] is Point of [:E,F:] ) ;
then A65: L . (x,(y1 + y2)) = u . ((IsoCPRLSP (E,F)) . (x,(y1 + y2))) by FUNCT_2:15
.= u . ((reproj (i2,xy)) . (y1 + y2)) by A54, defISO
.= L1 . (y1 + y2) by A47, FUNCT_1:13 ;
A66: L . (x,y1) = u . ((IsoCPRLSP (E,F)) . (x,y1)) by A46, FUNCT_2:15
.= u . ((reproj (i2,xy)) . y1) by A59, defISO
.= L1 . y1 by A47, FUNCT_1:13 ;
L . (x,y2) = u . ((IsoCPRLSP (E,F)) . (x,y2)) by A46, FUNCT_2:15
.= u . ((reproj (i2,xy)) . y2) by A64, defISO
.= L1 . y2 by A47, FUNCT_1:13 ;
hence L . (x,(y1 + y2)) = (L . (x,y1)) + (L . (x,y2)) by A65, A66, VECTSP_1:def 20; :: thesis: verum
end;
for x being Point of E
for y being Point of F
for a being Real holds L . (x,(a * y)) = a * (L . (x,y))
proof
let x be Point of E; :: thesis: for y being Point of F
for a being Real holds L . (x,(a * y)) = a * (L . (x,y))

let y be Point of F; :: thesis: for a being Real holds L . (x,(a * y)) = a * (L . (x,y))
let a be Real; :: thesis: L . (x,(a * y)) = a * (L . (x,y))
reconsider xy = <*x,y*> as Point of (product <*E,F*>) by PRVECT_3:14;
reconsider L1 = u * (reproj (i2,xy)) as LinearOperator of F,G by LOPBAN10:def 3;
A70: dom (reproj (i2,xy)) = the carrier of (<*E,F*> . i2) by FUNCT_2:def 1
.= the carrier of F ;
len xy = 2 by FINSEQ_1:44;
then dom xy = {1,2} by FINSEQ_1:2, FINSEQ_1:def 3;
then A72: i2 in dom xy by TARSKI:def 2;
then A80: (xy +* (i2,y)) . 2 = y by FUNCT_7:31;
A73: len (xy +* (i2,(a * y))) = 2 by LemmaA;
A74: (xy +* (i2,(a * y))) . 1 = xy . i1 by FUNCT_7:32
.= x ;
A75: (xy +* (i2,(a * y))) . 2 = a * y by A72, FUNCT_7:31;
reconsider x1x2 = a * y as Element of (<*E,F*> . i2) ;
A77: (reproj (i2,xy)) . x1x2 = xy +* (i2,(a * y)) by NDIFF5def4
.= <*x,(a * y)*> by A73, A74, A75, FINSEQ_1:44 ;
A78: len (xy +* (i2,y)) = 2 by LemmaA;
A79: (xy +* (i2,y)) . 1 = xy . i1 by FUNCT_7:32
.= x ;
A82: (reproj (i2,xy)) . y = xy +* (i2,y) by NDIFF5def4
.= <*x,y*> by A78, A79, A80, FINSEQ_1:44 ;
A69: ( [x,y] is Point of [:E,F:] & [x,(a * y)] is Point of [:E,F:] ) ;
then A83: L . (x,(a * y)) = u . ((IsoCPRLSP (E,F)) . (x,(a * y))) by FUNCT_2:15
.= u . ((reproj (i2,xy)) . (a * y)) by A77, defISO
.= L1 . (a * y) by A70, FUNCT_1:13 ;
L . (x,y) = u . ((IsoCPRLSP (E,F)) . (x,y)) by A69, FUNCT_2:15
.= u . ((reproj (i2,xy)) . y) by A82, defISO
.= L1 . y by A70, FUNCT_1:13 ;
hence L . (x,(a * y)) = a * (L . (x,y)) by A83, LOPBAN_1:def 5; :: thesis: verum
end;
hence u * (IsoCPRLSP (E,F)) is BilinearOperator of E,F,G by A2, A26, A44, LOPBAN_8:11; :: thesis: verum