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(x, a), y) → f(y, f(x, y))

Q is empty.


QTRS

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

f(f(x, a), y) → f(y, f(x, y))

Q is empty.