for X, Y being RealLinearSpace
for n being Nat
for x being FinSequence of the carrier of X
for y being FinSequence of the carrier of Y
for z being FinSequence of the carrier of (Prod_of_RLS (X,Y)) st len x = n & len y = n & len z = n & ( for i being Nat st i in Seg n holds
z . i = [(x . i),(y . i)] ) holds
Sum z = [(Sum x),(Sum y)]