Proof of B, C, K, W system

Question

There is a B,C,K,W system. In particular, there is presented the following identity:

$B = S (K S) K$

How to prove this statement?

Answer 1

Consider $B x y z$ and $(S (K S) K) x y z$ and use the Church-Rosser theorem to show that they have the same normal form for all $x,y$ and $z$.