Certification Problem

Input (TPDB SRS_Standard/Mixed_SRS/touzet)

The rewrite relation of the following TRS is considered.

a(b(x1)) b(b(b(x1))) (1)
b(a(x1)) a(a(a(x1))) (2)
a(x1) x1 (3)
b(x1) x1 (4)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by ttt2 @ termCOMP 2023)

1 Dependency Pair Transformation

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

1.1 Reduction Pair Processor with Usable Rules

Using the linear polynomial interpretation over (2 x 2)-matrices with strict dimension 1 over the arctic semiring over the integers
[a(x1)] =
0 -∞
2 0
· x1 +
-∞ -∞
0 -∞
[b#(x1)] =
0 0
-∞ -∞
· x1 +
0 -∞
-∞ -∞
[b(x1)] =
0 0
0 0
· x1 +
0 -∞
0 -∞
[a#(x1)] =
2 0
-∞ -∞
· x1 +
0 -∞
-∞ -∞
together with the usable rules
a(b(x1)) b(b(b(x1))) (1)
b(a(x1)) a(a(a(x1))) (2)
a(x1) x1 (3)
b(x1) x1 (4)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
a#(b(x1)) b#(b(x1)) (5)
a#(b(x1)) b#(b(b(x1))) (6)
could be deleted.

1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.