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:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(0, Y) → 0
g(X, s(Y)) → g(X, Y)
Q is empty.
↳ QTRS
↳ RRRPoloQTRSProof
Q restricted rewrite system:
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(0, Y) → 0
g(X, s(Y)) → g(X, Y)
Q is empty.
The following Q TRS is given: Q restricted rewrite system:
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(0, Y) → 0
g(X, s(Y)) → g(X, Y)
Q is empty.
The following rules can be removed by the rule removal processor [15] because they are oriented strictly by a polynomial ordering:
g(0, Y) → 0
Used ordering:
Polynomial interpretation [25]:
POL(0) = 0
POL(f(x1, x2, x3)) = x1 + x2 + 2·x3
POL(g(x1, x2)) = 2 + x1 + x2
POL(h(x1, x2)) = 2·x1 + 2·x2
POL(s(x1)) = x1
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
Q restricted rewrite system:
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(X, s(Y)) → g(X, Y)
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:
G(X, s(Y)) → G(X, Y)
H(X, Z) → F(X, s(X), Z)
F(X, Y, g(X, Y)) → H(0, g(X, Y))
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(X, s(Y)) → g(X, Y)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
Q DP problem:
The TRS P consists of the following rules:
G(X, s(Y)) → G(X, Y)
H(X, Z) → F(X, s(X), Z)
F(X, Y, g(X, Y)) → H(0, g(X, Y))
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(X, s(Y)) → g(X, Y)
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.
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ UsableRulesProof
↳ QDP
Q DP problem:
The TRS P consists of the following rules:
G(X, s(Y)) → G(X, Y)
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(X, s(Y)) → g(X, Y)
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
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ UsableRulesProof
↳ QDP
↳ QDPSizeChangeProof
↳ QDP
Q DP problem:
The TRS P consists of the following rules:
G(X, s(Y)) → G(X, Y)
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:
- G(X, s(Y)) → G(X, Y)
The graph contains the following edges 1 >= 1, 2 > 2
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
Q DP problem:
The TRS P consists of the following rules:
H(X, Z) → F(X, s(X), Z)
F(X, Y, g(X, Y)) → H(0, g(X, Y))
The TRS R consists of the following rules:
h(X, Z) → f(X, s(X), Z)
f(X, Y, g(X, Y)) → h(0, g(X, Y))
g(X, s(Y)) → g(X, Y)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By using the usable rules with reduction pair processor [15] with a polynomial ordering [25], all dependency pairs and the corresponding usable rules [17] can be oriented non-strictly. All non-usable rules are removed, and those dependency pairs and usable rules that have been oriented strictly or contain non-usable symbols in their left-hand side are removed as well.
No dependency pairs are removed.
No rules are removed from R.
Used ordering: POLO with Polynomial interpretation [25]:
POL(0) = 0
POL(F(x1, x2, x3)) = x1 + x2 + x3
POL(H(x1, x2)) = 2·x1 + x2
POL(g(x1, x2)) = 1 + x1 + 2·x2
POL(s(x1)) = x1
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
↳ QDP
↳ Instantiation
Q DP problem:
The TRS P consists of the following rules:
H(X, Z) → F(X, s(X), Z)
F(X, Y, g(X, Y)) → H(0, g(X, Y))
The TRS R consists of the following rules:
g(X, s(Y)) → g(X, Y)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By instantiating [15] the rule H(X, Z) → F(X, s(X), Z) we obtained the following new rules:
H(0, y_2) → F(0, s(0), y_2)
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
↳ QDP
↳ Instantiation
↳ QDP
↳ Instantiation
Q DP problem:
The TRS P consists of the following rules:
F(X, Y, g(X, Y)) → H(0, g(X, Y))
H(0, y_2) → F(0, s(0), y_2)
The TRS R consists of the following rules:
g(X, s(Y)) → g(X, Y)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By instantiating [15] the rule F(X, Y, g(X, Y)) → H(0, g(X, Y)) we obtained the following new rules:
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
↳ QDP
↳ Instantiation
↳ QDP
↳ Instantiation
↳ QDP
↳ RuleRemovalProof
Q DP problem:
The TRS P consists of the following rules:
H(0, y_2) → F(0, s(0), y_2)
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
The TRS R consists of the following rules:
g(X, s(Y)) → g(X, Y)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By using the rule removal processor [15] with the following polynomial ordering [25], at least one Dependency Pair or term rewrite system rule of this QDP problem can be strictly oriented.
Strictly oriented rules of the TRS R:
g(X, s(Y)) → g(X, Y)
Used ordering: POLO with Polynomial interpretation [25]:
POL(0) = 1
POL(F(x1, x2, x3)) = 2·x1 + x2 + x3
POL(H(x1, x2)) = 2 + 2·x1 + x2
POL(g(x1, x2)) = 2 + x1 + 2·x2
POL(s(x1)) = 1 + x1
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
↳ QDP
↳ Instantiation
↳ QDP
↳ Instantiation
↳ QDP
↳ RuleRemovalProof
↳ QDP
↳ Instantiation
Q DP problem:
The TRS P consists of the following rules:
H(0, y_2) → F(0, s(0), y_2)
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
R is empty.
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By instantiating [15] the rule H(0, y_2) → F(0, s(0), y_2) we obtained the following new rules:
H(0, g(0, s(0))) → F(0, s(0), g(0, s(0)))
↳ QTRS
↳ RRRPoloQTRSProof
↳ QTRS
↳ DependencyPairsProof
↳ QDP
↳ DependencyGraphProof
↳ AND
↳ QDP
↳ QDP
↳ UsableRulesReductionPairsProof
↳ QDP
↳ Instantiation
↳ QDP
↳ Instantiation
↳ QDP
↳ RuleRemovalProof
↳ QDP
↳ Instantiation
↳ QDP
↳ NonTerminationProof
Q DP problem:
The TRS P consists of the following rules:
H(0, g(0, s(0))) → F(0, s(0), g(0, s(0)))
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
R is empty.
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:
H(0, g(0, s(0))) → F(0, s(0), g(0, s(0)))
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
The TRS R consists of the following rules:none
s = F(0, s(0), g(0, s(0))) evaluates to t =F(0, s(0), g(0, s(0)))
Thus s starts an infinite chain as s semiunifies with t with the following substitutions:
- Semiunifier: [ ]
- Matcher: [ ]
Rewriting sequence
F(0, s(0), g(0, s(0))) → H(0, g(0, s(0)))
with rule F(0, s(0), g(0, s(0))) → H(0, g(0, s(0))) at position [] and matcher [ ]
H(0, g(0, s(0))) → F(0, s(0), g(0, s(0)))
with rule H(0, g(0, s(0))) → F(0, s(0), g(0, s(0)))
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.