MAYBE

Problem:
 sq(0(x1)) -> p(s(p(s(p(p(p(p(s(s(s(s(0(p(s(p(s(x1)))))))))))))))))
 sq(s(x1)) ->
 s(p(s(p(s(p(p(s(s(twice(p(s(p(s(p(p(p(s(s(s(sq(p(p(p(p(p(p(s(s(s(s(s(s(x1)))))))))))))))))))))))))))))))))
 twice(0(x1)) ->
 p(p(p(p(s(s(p(s(s(s(0(p(p(p(s(s(s(p(p(s(s(p(s(p(s(p(s(x1)))))))))))))))))))))))))))
 twice(s(x1)) -> p(p(s(s(s(p(p(s(s(s(twice(p(s(p(s(x1)))))))))))))))
 p(p(s(x1))) -> p(x1)
 p(s(x1)) -> x1
 p(0(x1)) -> 0(s(s(s(s(s(s(s(s(s(s(s(x1))))))))))))
 0(x1) -> x1

Proof:
 Open