(VAR N X Y Z )
(RULES 
        from(X) -> cons(X, n__from(s(X)))
        2ndspos(0, Z) -> rnil
        2ndspos(s(N), cons(X, Z)) -> 2ndspos(s(N), cons2(X, activate(Z)))
        2ndspos(s(N), cons2(X, cons(Y, Z))) -> rcons(posrecip(Y), 2ndsneg(N, activate(Z)))
        2ndsneg(0, Z) -> rnil
        2ndsneg(s(N), cons(X, Z)) -> 2ndsneg(s(N), cons2(X, activate(Z)))
        2ndsneg(s(N), cons2(X, cons(Y, Z))) -> rcons(negrecip(Y), 2ndspos(N, activate(Z)))
        pi(X) -> 2ndspos(X, from(0))
        plus(0, Y) -> Y
        plus(s(X), Y) -> s(plus(X, Y))
        times(0, Y) -> 0
        times(s(X), Y) -> plus(Y, times(X, Y))
        square(X) -> times(X, X)
        from(X) -> n__from(X)
        activate(n__from(X)) -> from(X)
        activate(X) -> X
        
)