MAYBE
MAYBE
TRS:
 {h(x, x) -> x,
  f(x, y) -> h(x, y),
  f(x, y) -> h(y, x)}
 DUP: We consider a non-duplicating system.
  Trs:
   {h(x, x) -> x,
    f(x, y) -> h(x, y),
    f(x, y) -> h(y, x)}
  Fail