let RNS1, RNS2 be RealLinearSpace; :: thesis: ( RLSStruct(# the carrier of RNS1, the ZeroF of RNS1, the addF of RNS1, the Mult of RNS1 #) = RLSStruct(# the carrier of RNS2, the ZeroF of RNS2, the addF of RNS2, the Mult of RNS2 #) implies for Ft being FinSequence of RNS1
for FFr being FinSequence of RNS2 st Ft = FFr holds
Sum Ft = Sum FFr )

assume A1: RLSStruct(# the carrier of RNS1, the ZeroF of RNS1, the addF of RNS1, the Mult of RNS1 #) = RLSStruct(# the carrier of RNS2, the ZeroF of RNS2, the addF of RNS2, the Mult of RNS2 #) ; :: thesis: for Ft being FinSequence of RNS1
for FFr being FinSequence of RNS2 st Ft = FFr holds
Sum Ft = Sum FFr

let F be FinSequence of RNS1; :: thesis: for FFr being FinSequence of RNS2 st F = FFr holds
Sum F = Sum FFr

let Fv be FinSequence of RNS2; :: thesis: ( F = Fv implies Sum F = Sum Fv )
assume A2: F = Fv ; :: thesis: Sum F = Sum Fv
set T = RNS1;
set V = RNS2;
consider f being sequence of the carrier of RNS1 such that
A3: Sum F = f . (len F) and
A4: f . 0 = 0. RNS1 and
A5: for j being Nat
for v being Element of RNS1 st j < len F & v = F . (j + 1) holds
f . (j + 1) = (f . j) + v by RLVECT_1:def 12;
consider fv being sequence of the carrier of RNS2 such that
A6: Sum Fv = fv . (len Fv) and
A7: fv . 0 = 0. RNS2 and
A8: for j being Nat
for v being Element of RNS2 st j < len Fv & v = Fv . (j + 1) holds
fv . (j + 1) = (fv . j) + v by RLVECT_1:def 12;
defpred S1[ Nat] means ( $1 <= len F implies f . $1 = fv . $1 );
A9: for i being Nat st S1[i] holds
S1[i + 1]
proof
let i be Nat; :: thesis: ( S1[i] implies S1[i + 1] )
assume A10: S1[i] ; :: thesis: S1[i + 1]
assume A11: i + 1 <= len F ; :: thesis: f . (i + 1) = fv . (i + 1)
then A12: i + 1 in dom F by NAT_1:11, FINSEQ_3:25;
then F . (i + 1) = F /. (i + 1) by PARTFUN1:def 6;
then A13: f . (i + 1) = (f . i) + (F /. (i + 1)) by A5, A11, NAT_1:13;
A14: Fv /. (i + 1) = Fv . (i + 1) by A2, A12, PARTFUN1:def 6;
thus f . (i + 1) = (fv . i) + (Fv /. (i + 1)) by A10, A11, A13, NAT_1:13, A1, A2
.= fv . (i + 1) by A2, A8, A11, NAT_1:13, A14 ; :: thesis: verum
end;
A15: S1[ 0 ] by A4, A7, A1;
for n being Nat holds S1[n] from NAT_1:sch 2(A15, A9);
hence Sum F = Sum Fv by A2, A3, A6; :: thesis: verum