YES
Time: 0.001638
TRS:
 {f(f(x, a()), y) -> f(f(a(), y), f(a(), x))}
 DP:
  DP:
   {f#(f(x, a()), y) -> f#(f(a(), y), f(a(), x)),
    f#(f(x, a()), y) -> f#(a(), y),
    f#(f(x, a()), y) -> f#(a(), x)}
  TRS:
  {f(f(x, a()), y) -> f(f(a(), y), f(a(), x))}
  EDG:
   {}
   STATUS:
    arrows: 1.000000
    SCCS (0):