(0) Obligation:

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

g(f(x), y) → f(h(x, y))
h(x, y) → g(x, f(y))

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:

g(f(x), y) → f(h(x, y))
h(x, y) → g(x, f(y))

The set Q consists of the following terms:

g(f(x0), x1)
h(x0, x1)

(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:

G(f(x), y) → H(x, y)
H(x, y) → G(x, f(y))

The TRS R consists of the following rules:

g(f(x), y) → f(h(x, y))
h(x, y) → g(x, f(y))

The set Q consists of the following terms:

g(f(x0), x1)
h(x0, x1)

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

(5) UsableRulesProof (EQUIVALENT transformation)

As all Q-normal forms are R-normal forms we are in the innermost case. Hence, by the usable rules processor [LPAR04] we can delete all non-usable rules [FROCOS05] from R.

(6) Obligation:

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

G(f(x), y) → H(x, y)
H(x, y) → G(x, f(y))

R is empty.
The set Q consists of the following terms:

g(f(x0), x1)
h(x0, x1)

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

(7) QReductionProof (EQUIVALENT transformation)

We deleted the following terms from Q as each root-symbol of these terms does neither occur in P nor in R.[THIEMANN].

g(f(x0), x1)
h(x0, x1)

(8) Obligation:

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

G(f(x), y) → H(x, y)
H(x, y) → G(x, f(y))

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

(9) QDPSizeChangeProof (EQUIVALENT transformation)

By using the subterm criterion [SUBTERM_CRITERION] together with the size-change analysis [AAECC05] we have proven that there are no infinite chains for this DP problem.

From the DPs we obtained the following set of size-change graphs:

  • H(x, y) → G(x, f(y))
    The graph contains the following edges 1 >= 1

  • G(f(x), y) → H(x, y)
    The graph contains the following edges 1 > 1, 2 >= 2

(10) TRUE