set K = F_Complex ;
set L = LKer f;
set vq = VectQuot V,(LKer f);
set Cv = CosetSet V,(LKer f);
set aCv = addCoset V,(LKer f);
set mCv = lmultCoset V,(LKer f);
set R = RKer (f *' );
set wq = VectQuot W,(RKer (f *' ));
set Cw = CosetSet W,(RKer (f *' ));
set aCw = addCoset W,(RKer (f *' ));
set mCw = lmultCoset W,(RKer (f *' ));
A1: CosetSet V,(LKer f) = the carrier of (VectQuot V,(LKer f)) by VECTSP10:def 6;
A2: CosetSet W,(RKer (f *' )) = the carrier of (VectQuot W,(RKer (f *' ))) by VECTSP10:def 6;
A3: rightker f = rightker (f *' ) by Th58;
defpred S1[ set , set , set ] means for v being Vector of V
for w being Vector of W st $1 = v + (LKer f) & $2 = w + (RKer (f *' )) holds
$3 = f . v,w;
A4: now
let A be Vector of (VectQuot V,(LKer f)); :: thesis: for B being Vector of (VectQuot W,(RKer (f *' ))) ex y being Element of the carrier of F_Complex st S1[A,B,y]
let B be Vector of (VectQuot W,(RKer (f *' ))); :: thesis: ex y being Element of the carrier of F_Complex st S1[A,B,y]
consider a being Vector of V such that
A5: A = a + (LKer f) by VECTSP10:23;
consider b being Vector of W such that
A6: B = b + (RKer (f *' )) by VECTSP10:23;
take y = f . a,b; :: thesis: S1[A,B,y]
now
let a1 be Vector of V; :: thesis: for b1 being Vector of W st A = a1 + (LKer f) & B = b1 + (RKer (f *' )) holds
y = f . a1,b1

let b1 be Vector of W; :: thesis: ( A = a1 + (LKer f) & B = b1 + (RKer (f *' )) implies y = f . a1,b1 )
assume A = a1 + (LKer f) ; :: thesis: ( B = b1 + (RKer (f *' )) implies y = f . a1,b1 )
then a in a1 + (LKer f) by A5, VECTSP_4:59;
then consider vv being Vector of V such that
A7: ( vv in LKer f & a = a1 + vv ) by VECTSP_4:57;
assume B = b1 + (RKer (f *' )) ; :: thesis: y = f . a1,b1
then b in b1 + (RKer (f *' )) by A6, VECTSP_4:59;
then consider ww being Vector of W such that
A8: ( ww in RKer (f *' ) & b = b1 + ww ) by VECTSP_4:57;
vv in the carrier of (LKer f) by A7, STRUCT_0:def 5;
then vv in leftker f by BILINEAR:def 19;
then consider aa being Vector of V such that
A9: ( aa = vv & ( for w0 being Vector of W holds f . aa,w0 = 0. F_Complex ) ) ;
ww in the carrier of (RKer (f *' )) by A8, STRUCT_0:def 5;
then ww in rightker (f *' ) by BILINEAR:def 20;
then consider bb being Vector of W such that
A10: ( bb = ww & ( for v0 being Vector of V holds f . v0,bb = 0. F_Complex ) ) by A3;
thus y = ((f . a1,b1) + (f . a1,ww)) + ((f . vv,b1) + (f . vv,ww)) by A7, A8, BILINEAR:29
.= ((f . a1,b1) + (0. F_Complex )) + ((f . vv,b1) + (f . vv,ww)) by A10
.= ((f . a1,b1) + (0. F_Complex )) + ((0. F_Complex ) + (f . vv,ww)) by A9
.= (f . a1,b1) + ((0. F_Complex ) + (f . vv,ww)) by RLVECT_1:def 7
.= (f . a1,b1) + (f . vv,ww) by RLVECT_1:10
.= (f . a1,b1) + (0. F_Complex ) by A9
.= f . a1,b1 by RLVECT_1:def 7 ; :: thesis: verum
end;
hence S1[A,B,y] ; :: thesis: verum
end;
consider ff being Function of [:the carrier of (VectQuot V,(LKer f)),the carrier of (VectQuot W,(RKer (f *' ))):],the carrier of F_Complex such that
A11: for A being Vector of (VectQuot V,(LKer f))
for B being Vector of (VectQuot W,(RKer (f *' ))) holds S1[A,B,ff . A,B] from BINOP_1:sch 3(A4);
reconsider ff = ff as Form of (VectQuot V,(LKer f)),(VectQuot W,(RKer (f *' ))) ;
A12: now
let ww be Vector of (VectQuot W,(RKer (f *' ))); :: thesis: FunctionalSAF ff,ww is additive
consider w being Vector of W such that
A13: ww = w + (RKer (f *' )) by VECTSP10:23;
set ffw = FunctionalSAF ff,ww;
now
let A, B be Vector of (VectQuot V,(LKer f)); :: thesis: (FunctionalSAF ff,ww) . (A + B) = ((FunctionalSAF ff,ww) . A) + ((FunctionalSAF ff,ww) . B)
consider a being Vector of V such that
A14: A = a + (LKer f) by VECTSP10:23;
consider b being Vector of V such that
A15: B = b + (LKer f) by VECTSP10:23;
A16: the addF of (VectQuot V,(LKer f)) = addCoset V,(LKer f) by VECTSP10:def 6;
A17: (addCoset V,(LKer f)) . A,B = (a + b) + (LKer f) by A1, A14, A15, VECTSP10:def 3;
thus (FunctionalSAF ff,ww) . (A + B) = ff . (the addF of (VectQuot V,(LKer f)) . A,B),ww by BILINEAR:10
.= f . (a + b),w by A11, A13, A16, A17
.= (f . a,w) + (f . b,w) by BILINEAR:27
.= (ff . A,ww) + (f . b,w) by A11, A13, A14
.= (ff . A,ww) + (ff . B,ww) by A11, A13, A15
.= ((FunctionalSAF ff,ww) . A) + (ff . B,ww) by BILINEAR:10
.= ((FunctionalSAF ff,ww) . A) + ((FunctionalSAF ff,ww) . B) by BILINEAR:10 ; :: thesis: verum
end;
hence FunctionalSAF ff,ww is additive by HAHNBAN1:def 11; :: thesis: verum
end;
A18: now
let vv be Vector of (VectQuot V,(LKer f)); :: thesis: FunctionalFAF ff,vv is additive
consider v being Vector of V such that
A19: vv = v + (LKer f) by VECTSP10:23;
set ffv = FunctionalFAF ff,vv;
now
let A, B be Vector of (VectQuot W,(RKer (f *' ))); :: thesis: (FunctionalFAF ff,vv) . (A + B) = ((FunctionalFAF ff,vv) . A) + ((FunctionalFAF ff,vv) . B)
consider a being Vector of W such that
A20: A = a + (RKer (f *' )) by VECTSP10:23;
consider b being Vector of W such that
A21: B = b + (RKer (f *' )) by VECTSP10:23;
A22: the addF of (VectQuot W,(RKer (f *' ))) = addCoset W,(RKer (f *' )) by VECTSP10:def 6;
A23: (addCoset W,(RKer (f *' ))) . A,B = (a + b) + (RKer (f *' )) by A2, A20, A21, VECTSP10:def 3;
thus (FunctionalFAF ff,vv) . (A + B) = ff . vv,(the addF of (VectQuot W,(RKer (f *' ))) . A,B) by BILINEAR:9
.= f . v,(a + b) by A11, A19, A22, A23
.= (f . v,a) + (f . v,b) by BILINEAR:28
.= (ff . vv,A) + (f . v,b) by A11, A19, A20
.= (ff . vv,A) + (ff . vv,B) by A11, A19, A21
.= ((FunctionalFAF ff,vv) . A) + (ff . vv,B) by BILINEAR:9
.= ((FunctionalFAF ff,vv) . A) + ((FunctionalFAF ff,vv) . B) by BILINEAR:9 ; :: thesis: verum
end;
hence FunctionalFAF ff,vv is additive by HAHNBAN1:def 11; :: thesis: verum
end;
A24: now
let ww be Vector of (VectQuot W,(RKer (f *' ))); :: thesis: FunctionalSAF ff,ww is homogeneous
consider w being Vector of W such that
A25: ww = w + (RKer (f *' )) by VECTSP10:23;
set ffw = FunctionalSAF ff,ww;
now
let A be Vector of (VectQuot V,(LKer f)); :: thesis: for r being Element of F_Complex holds (FunctionalSAF ff,ww) . (r * A) = r * ((FunctionalSAF ff,ww) . A)
let r be Element of F_Complex ; :: thesis: (FunctionalSAF ff,ww) . (r * A) = r * ((FunctionalSAF ff,ww) . A)
consider a being Vector of V such that
A26: A = a + (LKer f) by VECTSP10:23;
A27: the lmult of (VectQuot V,(LKer f)) = lmultCoset V,(LKer f) by VECTSP10:def 6;
A28: (lmultCoset V,(LKer f)) . r,A = (r * a) + (LKer f) by A1, A26, VECTSP10:def 5;
thus (FunctionalSAF ff,ww) . (r * A) = ff . (the lmult of (VectQuot V,(LKer f)) . r,A),ww by BILINEAR:10
.= f . (r * a),w by A11, A25, A27, A28
.= r * (f . a,w) by BILINEAR:32
.= r * (ff . A,ww) by A11, A25, A26
.= r * ((FunctionalSAF ff,ww) . A) by BILINEAR:10 ; :: thesis: verum
end;
hence FunctionalSAF ff,ww is homogeneous by HAHNBAN1:def 12; :: thesis: verum
end;
now
let vv be Vector of (VectQuot V,(LKer f)); :: thesis: FunctionalFAF ff,vv is cmplxhomogeneous
consider v being Vector of V such that
A29: vv = v + (LKer f) by VECTSP10:23;
set ffv = FunctionalFAF ff,vv;
now
let A be Vector of (VectQuot W,(RKer (f *' ))); :: thesis: for r being Element of F_Complex holds (FunctionalFAF ff,vv) . (r * A) = (r *' ) * ((FunctionalFAF ff,vv) . A)
let r be Element of F_Complex ; :: thesis: (FunctionalFAF ff,vv) . (r * A) = (r *' ) * ((FunctionalFAF ff,vv) . A)
consider a being Vector of W such that
A30: A = a + (RKer (f *' )) by VECTSP10:23;
A31: the lmult of (VectQuot W,(RKer (f *' ))) = lmultCoset W,(RKer (f *' )) by VECTSP10:def 6;
A32: (lmultCoset W,(RKer (f *' ))) . r,A = (r * a) + (RKer (f *' )) by A2, A30, VECTSP10:def 5;
thus (FunctionalFAF ff,vv) . (r * A) = ff . vv,(the lmult of (VectQuot W,(RKer (f *' ))) . r,A) by BILINEAR:9
.= f . v,(r * a) by A11, A29, A31, A32
.= (r *' ) * (f . v,a) by Th30
.= (r *' ) * (ff . vv,A) by A11, A29, A30
.= (r *' ) * ((FunctionalFAF ff,vv) . A) by BILINEAR:9 ; :: thesis: verum
end;
hence FunctionalFAF ff,vv is cmplxhomogeneous by Def1; :: thesis: verum
end;
then reconsider ff = ff as sesquilinear-Form of (VectQuot V,(LKer f)),(VectQuot W,(RKer (f *' ))) by A12, A18, A24, Def4, BILINEAR:def 12, BILINEAR:def 13, BILINEAR:def 15;
take ff ; :: thesis: for A being Vector of (VectQuot V,(LKer f))
for B being Vector of (VectQuot W,(RKer (f *' )))
for v being Vector of V
for w being Vector of W st A = v + (LKer f) & B = w + (RKer (f *' )) holds
ff . A,B = f . v,w

thus for A being Vector of (VectQuot V,(LKer f))
for B being Vector of (VectQuot W,(RKer (f *' )))
for v being Vector of V
for w being Vector of W st A = v + (LKer f) & B = w + (RKer (f *' )) holds
ff . A,B = f . v,w by A11; :: thesis: verum