for n, i being Nat for RAS being non emptyMidSp-likeReperAlgebraStr over n + 2 for W being ATLAS of RAS for v being Vector of W for x being Tuple of (n + 1),W holds ( ( for l being Nat of n st l = i holds (x +* (i,v)). l = v ) & ( for l, i being Nat of n st l <> i holds (x +* (i,v)). l = x . l ) )