YES
TRS:
 {f(f(x, a()), a()) -> f(f(f(x, a()), f(a(), a())), a())}
 DP:
  Strict:
   {f#(f(x, a()), a()) -> f#(f(x, a()), f(a(), a())),
    f#(f(x, a()), a()) -> f#(f(f(x, a()), f(a(), a())), a()),
    f#(f(x, a()), a()) -> f#(a(), a())}
  Weak:
  {f(f(x, a()), a()) -> f(f(f(x, a()), f(a(), a())), a())}
  EDG:
   {}
   SCCS:
    
    Qed