Certification Problem

Input (TPDB SRS_Standard/Bouchare_06/13)

The rewrite relation of the following TRS is considered.

a(a(b(x1))) → a(x1) (1)
a(b(a(x1))) → b(b(a(x1))) (2)
b(b(x1)) → a(a(a(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#(a(b(x1))) → a#(x1) (4)
a#(b(a(x1))) → b#(b(a(x1))) (5)
b#(b(x1)) → a#(a(a(x1))) (6)
b#(b(x1)) → a#(a(x1)) (7)
b#(b(x1)) → a#(x1) (8)

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)] =
0
-∞
-∞
+
-∞ 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
-∞
0
-∞
+
0 -∞ -∞
0 0 0
1 0 0
· x1
[b(x1)] =
0
-∞
-∞
+
0 0 0
0 -∞ 0
1 -∞ 0
· x1
[b#(x1)] =
-∞
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pair
a#(a(b(x1))) → a#(x1) (4)
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)] =
0
-∞
-∞
+
0 0 1
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[b(x1)] =
0
0
-∞
+
0 0 1
0 0 0
0 0 0
· x1
[a(x1)] =
0
0
-∞
+
0 0 1
0 0 -∞
-∞ -∞ 0
· x1
[b#(x1)] =
0
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pair
a#(b(a(x1))) → b#(b(a(x1))) (5)
could be deleted.

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.