MAYBE
Trs:
 {      min(0(), y) -> 0(),
    min(s(x), s(y)) -> s(min(x, y)),
        min(x, 0()) -> 0(),
        max(0(), y) -> y,
    max(s(x), s(y)) -> s(max(x, y)),
        max(x, 0()) -> x,
  minus(s(x), s(y)) -> s(minus(x, any(y))),
      minus(x, 0()) -> x,
    gcd(s(x), s(y)) -> gcd(minus(max(x, y), min(x, y)), s(min(x, y))),
          any(s(x)) -> s(s(any(x))),
             any(x) -> x}
 Comment:
  We consider a duplicating trs.
  FAIL:
   Open