TIMEOUT
MAYBE
Trs:
 {               f(g(x), x, y) -> y,
  f(f(x, y, z), u, f(x, y, v)) -> f(x, y, f(z, u, v)),
                    f(x, x, y) -> x,
                 f(x, y, g(y)) -> x,
                    f(x, y, y) -> y}
 Open