let Rseq be Function of [:NAT,NAT:],REAL; :: thesis: for n, m being Nat holds
( (Partial_Sums Rseq) . ((n + 1),m) = ((Partial_Sums_in_cod2 Rseq) . ((n + 1),m)) + ((Partial_Sums Rseq) . (n,m)) & (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . (n,(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,m)) )

let n, m be Nat; :: thesis: ( (Partial_Sums Rseq) . ((n + 1),m) = ((Partial_Sums_in_cod2 Rseq) . ((n + 1),m)) + ((Partial_Sums Rseq) . (n,m)) & (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . (n,(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,m)) )
set RPS = Partial_Sums Rseq;
set CPS = Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq);
set ROW = Partial_Sums_in_cod1 Rseq;
set COL = Partial_Sums_in_cod2 Rseq;
defpred S1[ Nat] means (Partial_Sums Rseq) . ((n + 1),$1) = ((Partial_Sums_in_cod2 Rseq) . ((n + 1),$1)) + ((Partial_Sums Rseq) . (n,$1));
a1: (Partial_Sums Rseq) . (n,0) = (Partial_Sums_in_cod1 Rseq) . (n,0) by DefCS;
(Partial_Sums Rseq) . ((n + 1),0) = (Partial_Sums_in_cod1 Rseq) . ((n + 1),0) by DefCS
.= ((Partial_Sums_in_cod1 Rseq) . (n,0)) + (Rseq . ((n + 1),0)) by DefRS ;
then a3: S1[ 0 ] by a1, DefCS;
a4: for k being Nat st S1[k] holds
S1[k + 1]
proof
let k be Nat; :: thesis: ( S1[k] implies S1[k + 1] )
assume A5: S1[k] ; :: thesis: S1[k + 1]
a6: (Partial_Sums_in_cod2 Rseq) . ((n + 1),(k + 1)) = ((Partial_Sums_in_cod2 Rseq) . ((n + 1),k)) + (Rseq . ((n + 1),(k + 1))) by DefCS;
(Partial_Sums Rseq) . (n,(k + 1)) = ((Partial_Sums Rseq) . (n,k)) + ((Partial_Sums_in_cod1 Rseq) . (n,(k + 1))) by DefCS;
then ((Partial_Sums_in_cod2 Rseq) . ((n + 1),(k + 1))) + ((Partial_Sums Rseq) . (n,(k + 1))) = ((Partial_Sums Rseq) . ((n + 1),k)) + ((Rseq . ((n + 1),(k + 1))) + ((Partial_Sums_in_cod1 Rseq) . (n,(k + 1)))) by A5, a6
.= ((Partial_Sums Rseq) . ((n + 1),k)) + ((Partial_Sums_in_cod1 Rseq) . ((n + 1),(k + 1))) by DefRS ;
hence S1[k + 1] by DefCS; :: thesis: verum
end;
for k being Nat holds S1[k] from NAT_1:sch 2(a3, a4);
hence (Partial_Sums Rseq) . ((n + 1),m) = ((Partial_Sums_in_cod2 Rseq) . ((n + 1),m)) + ((Partial_Sums Rseq) . (n,m)) ; :: thesis: (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . (n,(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,m))
defpred S2[ Nat] means (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . ($1,(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . ($1,(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . ($1,m));
b1: (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (0,m) = (Partial_Sums_in_cod2 Rseq) . (0,m) by DefRS;
(Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (0,(m + 1)) = (Partial_Sums_in_cod2 Rseq) . (0,(m + 1)) by DefRS
.= ((Partial_Sums_in_cod2 Rseq) . (0,m)) + (Rseq . (0,(m + 1))) by DefCS ;
then b3: S2[ 0 ] by b1, DefRS;
b4: for k being Nat st S2[k] holds
S2[k + 1]
proof
let k be Nat; :: thesis: ( S2[k] implies S2[k + 1] )
assume B5: S2[k] ; :: thesis: S2[k + 1]
b6: (Partial_Sums_in_cod1 Rseq) . ((k + 1),(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . (k,(m + 1))) + (Rseq . ((k + 1),(m + 1))) by DefRS;
(Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . ((k + 1),m) = ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (k,m)) + ((Partial_Sums_in_cod2 Rseq) . ((k + 1),m)) by DefRS;
then ((Partial_Sums_in_cod1 Rseq) . ((k + 1),(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . ((k + 1),m)) = ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (k,(m + 1))) + ((Rseq . ((k + 1),(m + 1))) + ((Partial_Sums_in_cod2 Rseq) . ((k + 1),m))) by B5, b6
.= ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (k,(m + 1))) + ((Partial_Sums_in_cod2 Rseq) . ((k + 1),(m + 1))) by DefCS ;
hence S2[k + 1] by DefRS; :: thesis: verum
end;
for k being Nat holds S2[k] from NAT_1:sch 2(b3, b4);
hence (Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,(m + 1)) = ((Partial_Sums_in_cod1 Rseq) . (n,(m + 1))) + ((Partial_Sums_in_cod1 (Partial_Sums_in_cod2 Rseq)) . (n,m)) ; :: thesis: verum