Certification Problem

Input (TPDB SRS_Standard/Waldmann_07_size12/size-12-alpha-3-num-455)

The rewrite relation of the following TRS is considered.

a(x1) → b(c(x1)) (1)
b(a(b(x1))) → c(x1) (2)
c(c(x1)) → a(a(b(x1))) (3)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
a#(x1) → b#(c(x1)) (4)
a#(x1) → c#(x1) (5)
b#(a(b(x1))) → c#(x1) (6)
c#(c(x1)) → a#(a(b(x1))) (7)
c#(c(x1)) → a#(b(x1)) (8)
c#(c(x1)) → b#(x1) (9)

1.1 Reduction Pair Processor

Using the linear polynomial interpretation over the naturals
[a#(x1)] = 1 + 1 · x1
[b#(x1)] = 1 · x1
[c(x1)] = 1 + 1 · x1
[c#(x1)] = 1 + 1 · x1
[a(x1)] = 1 + 1 · x1
[b(x1)] = 1 · x1
the pairs
c#(c(x1)) → a#(b(x1)) (8)
c#(c(x1)) → b#(x1) (9)
could be deleted.

1.1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[a#(x1)] =
1
-∞
-∞
+
0 0 1
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[b#(x1)] =
0
-∞
-∞
+
-∞ 0 -∞
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[c(x1)] =
0
0
1
+
0 1 1
-∞ -∞ 0
0 1 0
· x1
[c#(x1)] =
1
-∞
-∞
+
0 -∞ -∞
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
1
0
0
+
0 1 1
0 0 0
-∞ 0 0
· x1
[b(x1)] =
1
0
0
+
0 1 0
-∞ 0 -∞
-∞ 0 -∞
· x1
the pair
a#(x1) → b#(c(x1)) (4)
could be deleted.

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.