TRS:
 {   f(a()) -> f(c(a())),
    f(c(X)) -> X,
  f(c(a())) -> f(d(b())),
     f(a()) -> f(d(a())),
    f(d(X)) -> X,
  f(c(b())) -> f(d(a())),
    e(g(X)) -> e(X)}
 Fail