(VAR N X X1 X2 Y Z )
(RULES 
        from(X) -> cons(X, n__from(n__s(X)))
        2ndspos(0, Z) -> rnil
        2ndspos(s(N), cons(X, n__cons(Y, Z))) -> rcons(posrecip(activate(Y)), 2ndsneg(N, activate(Z)))
        2ndsneg(0, Z) -> rnil
        2ndsneg(s(N), cons(X, n__cons(Y, Z))) -> rcons(negrecip(activate(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)
        s(X) -> n__s(X)
        cons(X1, X2) -> n__cons(X1, X2)
        activate(n__from(X)) -> from(activate(X))
        activate(n__s(X)) -> s(activate(X))
        activate(n__cons(X1, X2)) -> cons(activate(X1), X2)
        activate(X) -> X
        
)