Certification Problem
Input (TPDB SRS_Standard/Waldmann_07_size12/size-12-alpha-3-num-195)
The rewrite relation of the following TRS is considered.
a(x1) |
→ |
x1 |
(1) |
a(b(x1)) |
→ |
b(b(a(a(c(a(x1)))))) |
(2) |
b(x1) |
→ |
x1 |
(3) |
c(c(x1)) |
→ |
x1 |
(4) |
Property / Task
Prove or disprove termination.Answer / Result
No.Proof (by AProVE @ termCOMP 2023)
1 Looping derivation
There is a looping derivation.
a b c b b →+ ε a b c b b a a c a
The derivation can be derived as follows.
-
a b →+ b b a a c a:
This is an original rule (OC1).
-
a →+ ε:
This is an original rule (OC1).
-
a b →+ b b a a c:
The overlap closure is obtained from the following two overlap closures (OC2).
-
a b →+ b b a a c a
-
a →+ ε
-
c c →+ ε:
This is an original rule (OC1).
-
a b c →+ b b a a:
The overlap closure is obtained from the following two overlap closures (OC2).
-
a b →+ b b a a c
-
c c →+ ε
-
b →+ ε:
This is an original rule (OC1).
-
a b c →+ b a a:
The overlap closure is obtained from the following two overlap closures (OC3).
-
a b c →+ a a:
The overlap closure is obtained from the following two overlap closures (OC3).
-
a b →+ b b a c a:
The overlap closure is obtained from the following two overlap closures (OC3).
-
a b →+ b b a a c a
-
a →+ ε
-
a b →+ b b c a:
The overlap closure is obtained from the following two overlap closures (OC3).
-
a b →+ b c a:
The overlap closure is obtained from the following two overlap closures (OC3).
-
a b c b →+ a b c a:
The overlap closure is obtained from the following two overlap closures (OC2).
-
a b c →+ a a
-
a b →+ b c a
-
a b c b b →+ a b c b b a a c a:
The overlap closure is obtained from the following two overlap closures (OC2).
-
a b c b →+ a b c a
-
a b →+ b b a a c a