MAYBE
Trs:
 {*(*(x, y), z) -> *(x, *(y, z)),
  *(+(y, z), x) -> +(*(x, y), *(x, z)),
  *(x, +(y, z)) -> +(*(x, y), *(x, z)),
  +(+(x, y), z) -> +(x, +(y, z))}
 Comment:
  We consider a duplicating trs.
  FAIL:
   Open