Termination w.r.t. Q of the following Term Rewriting System could not be shown:

Q restricted rewrite system:
The TRS R consists of the following rules:

f(f(a, x), a) → f(f(x, f(a, a)), a)

Q is empty.


QTRS

Q restricted rewrite system:
The TRS R consists of the following rules:

f(f(a, x), a) → f(f(x, f(a, a)), a)

Q is empty.