Certification Problem

Input (TPDB SRS_Standard/Waldmann_19/random-552)

The rewrite relation of the following TRS is considered.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
ab(bb(ba(aa(x1)))) → aa(aa(aa(aa(x1)))) (4)
ab(bb(ba(ab(x1)))) → aa(aa(aa(ab(x1)))) (5)
bb(ba(aa(aa(x1)))) → ba(aa(aa(aa(x1)))) (6)
bb(ba(aa(ab(x1)))) → ba(aa(aa(ab(x1)))) (7)
bb(ba(aa(aa(x1)))) → ba(ab(bb(ba(x1)))) (8)
bb(ba(aa(ab(x1)))) → ba(ab(bb(bb(x1)))) (9)

1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
bb#(ba(aa(aa(x1)))) → ab#(bb(ba(x1))) (10)
bb#(ba(aa(aa(x1)))) → bb#(ba(x1)) (11)
bb#(ba(aa(ab(x1)))) → ab#(bb(bb(x1))) (12)
bb#(ba(aa(ab(x1)))) → bb#(bb(x1)) (13)
bb#(ba(aa(ab(x1)))) → bb#(x1) (14)

1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.