(VAR X X1 X2 Y Z )
(RULES 
        2nd(cons(X, n__cons(Y, Z))) -> activate(Y)
        from(X) -> cons(X, n__from(s(X)))
        cons(X1, X2) -> n__cons(X1, X2)
        from(X) -> n__from(X)
        activate(n__cons(X1, X2)) -> cons(X1, X2)
        activate(n__from(X)) -> from(X)
        activate(X) -> X
        
)