(VAR X X1 X2 Y Z )
(RULES 
        and(true, X) -> activate(X)
        and(false, Y) -> false
        if(true, X, Y) -> activate(X)
        if(false, X, Y) -> activate(Y)
        add(0, X) -> activate(X)
        add(s(X), Y) -> s(n__add(activate(X), activate(Y)))
        first(0, X) -> nil
        first(s(X), cons(Y, Z)) -> cons(activate(Y), n__first(activate(X), activate(Z)))
        from(X) -> cons(activate(X), n__from(n__s(activate(X))))
        add(X1, X2) -> n__add(X1, X2)
        first(X1, X2) -> n__first(X1, X2)
        from(X) -> n__from(X)
        s(X) -> n__s(X)
        activate(n__add(X1, X2)) -> add(activate(X1), X2)
        activate(n__first(X1, X2)) -> first(activate(X1), activate(X2))
        activate(n__from(X)) -> from(X)
        activate(n__s(X)) -> s(X)
        activate(X) -> X
        
)