for n being Element of NAT
for x, y being FinSequence holds InnerVertices ((n + 1) -BitAdderStr (x,y)) = (InnerVertices (n -BitAdderStr (x,y))) \/ (InnerVertices (BitAdderWithOverflowStr ((x . (n + 1)),(y . (n + 1)),(n -BitMajorityOutput (x,y)))))