(0) Obligation:

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

f(a, f(f(a, x), a)) → f(f(a, f(a, x)), a)

Q is empty.

(1) DependencyPairsProof (EQUIVALENT transformation)

Using Dependency Pairs [AG00,LPAR04] we result in the following initial DP problem.

(2) Obligation:

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

F(a, f(f(a, x), a)) → F(f(a, f(a, x)), a)
F(a, f(f(a, x), a)) → F(a, f(a, x))

The TRS R consists of the following rules:

f(a, f(f(a, x), a)) → f(f(a, f(a, x)), a)

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

(3) DependencyGraphProof (EQUIVALENT transformation)

The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 1 SCC with 1 less node.

(4) Obligation:

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

F(a, f(f(a, x), a)) → F(a, f(a, x))

The TRS R consists of the following rules:

f(a, f(f(a, x), a)) → f(f(a, f(a, x)), a)

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

(5) QDPOrderProof (EQUIVALENT transformation)

We use the reduction pair processor [LPAR04].


The following pairs can be oriented strictly and are deleted.


F(a, f(f(a, x), a)) → F(a, f(a, x))
The remaining pairs can at least be oriented weakly.
Used ordering: Combined order from the following AFS and order.
F(x1, x2)  =  x2
a  =  a
f(x1, x2)  =  f(x1, x2)

Recursive Path Order [RPO].
Precedence:
a > f2

The following usable rules [FROCOS05] were oriented:

f(a, f(f(a, x), a)) → f(f(a, f(a, x)), a)

(6) Obligation:

Q DP problem:
P is empty.
The TRS R consists of the following rules:

f(a, f(f(a, x), a)) → f(f(a, f(a, x)), a)

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

(7) PisEmptyProof (EQUIVALENT transformation)

The TRS P is empty. Hence, there is no (P,Q,R) chain.

(8) TRUE