let D be non empty set ; :: thesis: for d being Element of D
for F1, F2 being FinSequence_of_Matrix of D holds block_diagonal ((F1 ^ F2),d) = block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)

let d be Element of D; :: thesis: for F1, F2 being FinSequence_of_Matrix of D holds block_diagonal ((F1 ^ F2),d) = block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)
let F1, F2 be FinSequence_of_Matrix of D; :: thesis: block_diagonal ((F1 ^ F2),d) = block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)
set F12 = F1 ^ F2;
set D1 = block_diagonal (F1,d);
set D2 = block_diagonal (F2,d);
set D12 = block_diagonal ((F1 ^ F2),d);
set DF = <*(block_diagonal (F1,d))*> ^ F2;
set DF2 = block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d);
set LF1 = Len F1;
set WF1 = Width F1;
set LF2 = Len F2;
set WF2 = Width F2;
set LF = Len (F1 ^ F2);
set WF = Width (F1 ^ F2);
A1: Len (F1 ^ F2) = (Len F1) ^ (Len F2) by Th14;
len (block_diagonal ((F1 ^ F2),d)) = Sum (Len (F1 ^ F2)) by Def5;
then A2: len (block_diagonal ((F1 ^ F2),d)) = (Sum (Len F1)) + (Sum (Len F2)) by A1, RVSUM_1:75;
A3: Len <*(block_diagonal (F1,d))*> = <*(len (block_diagonal (F1,d)))*> by Th15;
then A4: Sum (Len <*(block_diagonal (F1,d))*>) = len (block_diagonal (F1,d)) by RVSUM_1:73;
A5: block_diagonal (<*(block_diagonal (F1,d))*>,d) = block_diagonal (F1,d) by Th34;
A6: Sum (Width F1) = width (block_diagonal (F1,d)) by Def5;
A7: Len (<*(block_diagonal (F1,d))*> ^ F2) = (Len <*(block_diagonal (F1,d))*>) ^ (Len F2) by Th14;
A8: Width (F1 ^ F2) = (Width F1) ^ (Width F2) by Th18;
len (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) = Sum (Len (<*(block_diagonal (F1,d))*> ^ F2)) by Def5;
then A9: len (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) = (len (block_diagonal (F1,d))) + (Sum (Len F2)) by A7, A3, RVSUM_1:76;
A10: Width <*(block_diagonal (F1,d))*> = <*(width (block_diagonal (F1,d)))*> by Th19;
then A11: Sum (Width <*(block_diagonal (F1,d))*>) = width (block_diagonal (F1,d)) by RVSUM_1:73;
A12: Sum (Len F1) = len (block_diagonal (F1,d)) by Def5;
A13: width (block_diagonal (F1,d)) = Sum (Width F1) by Def5;
A14: width (block_diagonal ((F1 ^ F2),d)) = Sum (Width (F1 ^ F2)) by Def5;
then A15: width (block_diagonal ((F1 ^ F2),d)) = (Sum (Width F1)) + (Sum (Width F2)) by A8, RVSUM_1:75;
A16: Width (<*(block_diagonal (F1,d))*> ^ F2) = (Width <*(block_diagonal (F1,d))*>) ^ (Width F2) by Th18;
A17: len (block_diagonal (F1,d)) = Sum (Len F1) by Def5;
width (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) = Sum (Width (<*(block_diagonal (F1,d))*> ^ F2)) by Def5;
then A18: width (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) = (width (block_diagonal (F1,d))) + (Sum (Width F2)) by A16, A10, RVSUM_1:76;
A19: Indices (block_diagonal ((F1 ^ F2),d)) = [:(Seg (len (block_diagonal ((F1 ^ F2),d)))),(Seg (width (block_diagonal ((F1 ^ F2),d)))):] by FINSEQ_1:def 3
.= Indices (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) by A2, A15, A17, A13, A9, A18, FINSEQ_1:def 3 ;
now :: thesis: for i, j being Nat st [i,j] in Indices (block_diagonal ((F1 ^ F2),d)) holds
(block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
A20: dom (block_diagonal ((F1 ^ F2),d)) = Seg (len (block_diagonal ((F1 ^ F2),d))) by FINSEQ_1:def 3;
let i, j be Nat; :: thesis: ( [i,j] in Indices (block_diagonal ((F1 ^ F2),d)) implies (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j) )
assume A21: [i,j] in Indices (block_diagonal ((F1 ^ F2),d)) ; :: thesis: (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
i in dom (block_diagonal ((F1 ^ F2),d)) by A21, ZFMISC_1:87;
then A22: 1 <= i by A20, FINSEQ_1:1;
j in Seg (width (block_diagonal ((F1 ^ F2),d))) by A21, ZFMISC_1:87;
then A23: 1 <= j by FINSEQ_1:1;
now :: thesis: (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
per cases ( ( i <= Sum (Len F1) & j <= Sum (Width F1) ) or ( i > Sum (Len F1) & j <= Sum (Width F1) ) or ( i <= Sum (Len F1) & j > Sum (Width F1) ) or ( i > Sum (Len F1) & j > Sum (Width F1) ) ) ;
suppose A24: ( i <= Sum (Len F1) & j <= Sum (Width F1) ) ; :: thesis: (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
then A25: i in dom (block_diagonal (F1,d)) by A12, A22, FINSEQ_3:25;
j in Seg (width (block_diagonal (F1,d))) by A6, A23, A24;
then A26: [i,j] in Indices (block_diagonal (F1,d)) by A25, ZFMISC_1:87;
hence (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal (F1,d)) * (i,j) by Th26
.= (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j) by A5, A26, Th26 ;
:: thesis: verum
end;
suppose A27: ( ( i > Sum (Len F1) & j <= Sum (Width F1) ) or ( i <= Sum (Len F1) & j > Sum (Width F1) ) ) ; :: thesis: (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
hence (block_diagonal ((F1 ^ F2),d)) * (i,j) = d by A21, Th29
.= (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j) by A17, A13, A4, A11, A19, A21, A27, Th29 ;
:: thesis: verum
end;
suppose A28: ( i > Sum (Len F1) & j > Sum (Width F1) ) ; :: thesis: (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j)
then reconsider ii = i - (Sum (Len F1)), jj = j - (Sum (Width F1)) as Element of NAT by NAT_1:21;
A29: jj <> 0 by A28;
A30: i = ii + (Sum (Len F1)) ;
A31: j = jj + (Sum (Width F1)) ;
ii <> 0 by A28;
then A32: [ii,jj] in Indices (block_diagonal (F2,d)) by A21, A30, A31, A29, Th27;
hence (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal (F2,d)) * (ii,jj) by A30, A31, Th28
.= (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j) by A17, A13, A4, A11, A30, A31, A32, Th28 ;
:: thesis: verum
end;
end;
end;
hence (block_diagonal ((F1 ^ F2),d)) * (i,j) = (block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d)) * (i,j) ; :: thesis: verum
end;
hence block_diagonal ((F1 ^ F2),d) = block_diagonal ((<*(block_diagonal (F1,d))*> ^ F2),d) by A14, A8, A2, A17, A13, A9, A18, MATRIX_0:21, RVSUM_1:75; :: thesis: verum