(0) Obligation:

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

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

Q is empty.

(1) Overlay + Local Confluence (EQUIVALENT transformation)

The TRS is overlay and locally confluent. By [NOC] we can switch to innermost.

(2) Obligation:

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

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

The set Q consists of the following terms:

f(f(a, x0), a)

(3) DependencyPairsProof (EQUIVALENT transformation)

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

(4) Obligation:

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

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

The TRS R consists of the following rules:

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

The set Q consists of the following terms:

f(f(a, x0), a)

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

(5) DependencyGraphProof (EQUIVALENT transformation)

The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 1 SCC with 3 less nodes.

(6) Obligation:

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

F(f(a, x), a) → F(x, a)

The TRS R consists of the following rules:

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

The set Q consists of the following terms:

f(f(a, x0), a)

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

(7) QDPOrderProof (EQUIVALENT transformation)

We use the reduction pair processor [LPAR04].


The following pairs can be oriented strictly and are deleted.


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

Lexicographic Path Order [LPO].
Precedence:
trivial

The following usable rules [FROCOS05] were oriented:

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

(8) Obligation:

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

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

The set Q consists of the following terms:

f(f(a, x0), a)

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

(9) PisEmptyProof (EQUIVALENT transformation)

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

(10) TRUE