MAYBE

Problem:
 strict:
  b(q(b(x1))) -> b(p(b(x1)))
 weak:
  0(p(0(x1))) -> q(x1)
  1(p(1(x1))) -> q(x1)
  0(q(0(x1))) -> q(x1)
  1(q(1(x1))) -> q(x1)
  p(x1) -> 1(p(1(0(1(x1)))))

Proof:
 Open