(VAR X X1 X2 Y )
(RULES 
        f(g(X), Y) -> f(X, n__f(g(X), activate(Y)))
        f(X1, X2) -> n__f(X1, X2)
        activate(n__f(X1, X2)) -> f(X1, X2)
        activate(X) -> X
        
)