(VAR N X X1 X2 XS )
(RULES 
        from(X) -> cons(X, n__from(n__s(X)))
        head(cons(X, XS)) -> X
        2nd(cons(X, XS)) -> head(activate(XS))
        take(0, XS) -> nil
        take(s(N), cons(X, XS)) -> cons(X, n__take(N, activate(XS)))
        sel(0, cons(X, XS)) -> X
        sel(s(N), cons(X, XS)) -> sel(N, activate(XS))
        from(X) -> n__from(X)
        s(X) -> n__s(X)
        take(X1, X2) -> n__take(X1, X2)
        activate(n__from(X)) -> from(activate(X))
        activate(n__s(X)) -> s(activate(X))
        activate(n__take(X1, X2)) -> take(activate(X1), activate(X2))
        activate(X) -> X
        
)