Termination w.r.t. Q proof of TRS/nontermin/CSREx1

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:

f₃(a, b, X) -> f₃(X, X, X)
c -> a
c -> b

Q is empty.

↳ QTRS

  ↳ DependencyPairsProof

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

f₃(a, b, X) -> f₃(X, X, X)
c -> a
c -> b

Q is empty.

Using Dependency Pairs [1,13] we result in the following initial DP problem:
Q DP problem:
The TRS P consists of the following rules:

F₃(a, b, X) -> F₃(X, X, X)

The TRS R consists of the following rules:

f₃(a, b, X) -> f₃(X, X, X)
c -> a
c -> b

Q is empty.
We have to consider all minimal (P,Q,R)-chains.

↳ QTRS

  ↳ DependencyPairsProof

    ↳ QDP

Q DP problem:
The TRS P consists of the following rules:

F₃(a, b, X) -> F₃(X, X, X)

The TRS R consists of the following rules:

f₃(a, b, X) -> f₃(X, X, X)
c -> a
c -> b

Q is empty.
We have to consider all minimal (P,Q,R)-chains.