Termination w.r.t. Q of the following Term Rewriting System could be disproven:
Q restricted rewrite system:
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
↳ QTRS
↳ DependencyPairsProof
Q restricted rewrite system:
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
Using Dependency Pairs [1,15] we result in the following initial DP problem:
Q DP problem:
The TRS P consists of the following rules:
F(0, 1, g(x, y), z) → F(g(x, y), g(x, y), g(x, y), h(x))
H(g(x, y)) → H(x)
F(0, 1, g(x, y), z) → H(x)
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
Q DP problem:
The TRS P consists of the following rules:
F(0, 1, g(x, y), z) → F(g(x, y), g(x, y), g(x, y), h(x))
H(g(x, y)) → H(x)
F(0, 1, g(x, y), z) → H(x)
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
The approximation of the Dependency Graph [15,17,22] contains 2 SCCs with 1 less node.
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ UsableRulesProof
↳ QDP
Q DP problem:
The TRS P consists of the following rules:
H(g(x, y)) → H(x)
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
We can use the usable rules and reduction pair processor [15] with the Ce-compatible extension of the polynomial order that maps every function symbol to the sum of its argument. Then, we can delete all non-usable rules [17] from R.
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ UsableRulesProof
↳ QDP
↳ QDPSizeChangeProof
↳ QDP
Q DP problem:
The TRS P consists of the following rules:
H(g(x, y)) → H(x)
R is empty.
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By using the subterm criterion [20] together with the size-change analysis [32] 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(g(x, y)) → H(x)
The graph contains the following edges 1 > 1
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ NonTerminationProof
Q DP problem:
The TRS P consists of the following rules:
F(0, 1, g(x, y), z) → F(g(x, y), g(x, y), g(x, y), h(x))
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
We used the non-termination processor [17] to show that the DP problem is infinite.
Found a loop by narrowing to the left:
The TRS P consists of the following rules:
F(0, 1, g(x, y), z) → F(g(x, y), g(x, y), g(x, y), h(x))
The TRS R consists of the following rules:
f(0, 1, g(x, y), z) → f(g(x, y), g(x, y), g(x, y), h(x))
g(0, 1) → 0
g(0, 1) → 1
h(g(x, y)) → h(x)
s = F(g(0, 1), g(0, 1), g(x, y), z) evaluates to t =F(g(x, y), g(x, y), g(x, y), h(x))
Thus s starts an infinite chain as s semiunifies with t with the following substitutions:
- Semiunifier: [z / h(0), y / 1, x / 0]
- Matcher: [ ]
Rewriting sequence
F(g(0, 1), g(0, 1), g(0, 1), h(0)) → F(g(0, 1), 1, g(0, 1), h(0))
with rule g(0, 1) → 1 at position [1] and matcher [ ]
F(g(0, 1), 1, g(0, 1), h(0)) → F(0, 1, g(0, 1), h(0))
with rule g(0, 1) → 0 at position [0] and matcher [ ]
F(0, 1, g(0, 1), h(0)) → F(g(0, 1), g(0, 1), g(0, 1), h(0))
with rule F(0, 1, g(x, y), z) → F(g(x, y), g(x, y), g(x, y), h(x))
Now applying the matcher to the start term leads to a term which is equal to the last term in the rewriting sequence
All these steps are and every following step will be a correct step w.r.t to Q.