(VAR N X Y Z )
(RULES 
        2ndspos(s(N), cons(X)) -> rcons(posrecip(Y), 2ndsneg(N, Z))
        2ndsneg(s(N), cons(X)) -> rcons(negrecip(Y), 2ndspos(N, Z))
        from(X) -> cons(X)
        2ndspos(0, Z) -> rnil
        2ndsneg(0, Z) -> rnil
        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)
        
)