1. Prove that, for any structure function, , (x) = xi(1i, x) + (1 xi)(0i, x)...

1. Prove that, for any structure function, φ,

φ(x) = xiφ(1i, x) + (1 − xi)φ(0i, x)

where

(1i, x) = (x1,...,xi−1, 1,xi+1,...,xn),

(0i, x) = (x1,...,xi−1, 0,xi+1,...,xn)