Certification Problem

Input (TPDB SRS_Standard/Waldmann_19/random-27)

The rewrite relation of the following TRS is considered.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Closure Under Flat Contexts

Using the flat contexts

{b(☐), a(☐)}

We obtain the transformed TRS
b(a(b(a(x1)))) → b(b(a(b(x1)))) (3)
b(b(a(a(b(x1))))) → b(a(a(a(b(x1))))) (4)
a(b(a(a(b(x1))))) → a(a(a(a(b(x1))))) (5)
b(b(a(a(a(x1))))) → b(a(a(b(b(x1))))) (6)
a(b(a(a(a(x1))))) → a(a(a(b(b(x1))))) (7)

1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
ba(ab(ba(ab(x1)))) → bb(ba(ab(bb(x1)))) (8)
ba(ab(ba(aa(x1)))) → bb(ba(ab(ba(x1)))) (9)
bb(ba(aa(ab(bb(x1))))) → ba(aa(aa(ab(bb(x1))))) (10)
bb(ba(aa(ab(ba(x1))))) → ba(aa(aa(ab(ba(x1))))) (11)
ab(ba(aa(ab(bb(x1))))) → aa(aa(aa(ab(bb(x1))))) (12)
ab(ba(aa(ab(ba(x1))))) → aa(aa(aa(ab(ba(x1))))) (13)
bb(ba(aa(aa(ab(x1))))) → ba(aa(ab(bb(bb(x1))))) (14)
bb(ba(aa(aa(aa(x1))))) → ba(aa(ab(bb(ba(x1))))) (15)
ab(ba(aa(aa(ab(x1))))) → aa(aa(ab(bb(bb(x1))))) (16)
ab(ba(aa(aa(aa(x1))))) → aa(aa(ab(bb(ba(x1))))) (17)

1.1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
ba#(ab(ba(ab(x1)))) → bb#(ba(ab(bb(x1)))) (18)
ba#(ab(ba(ab(x1)))) → ba#(ab(bb(x1))) (19)
ba#(ab(ba(ab(x1)))) → ab#(bb(x1)) (20)
ba#(ab(ba(ab(x1)))) → bb#(x1) (21)
ba#(ab(ba(aa(x1)))) → bb#(ba(ab(ba(x1)))) (22)
ba#(ab(ba(aa(x1)))) → ba#(ab(ba(x1))) (23)
ba#(ab(ba(aa(x1)))) → ab#(ba(x1)) (24)
ba#(ab(ba(aa(x1)))) → ba#(x1) (25)
bb#(ba(aa(ab(bb(x1))))) → ba#(aa(aa(ab(bb(x1))))) (26)
bb#(ba(aa(ab(ba(x1))))) → ba#(aa(aa(ab(ba(x1))))) (27)
bb#(ba(aa(aa(ab(x1))))) → ba#(aa(ab(bb(bb(x1))))) (28)
bb#(ba(aa(aa(ab(x1))))) → ab#(bb(bb(x1))) (29)
bb#(ba(aa(aa(ab(x1))))) → bb#(bb(x1)) (30)
bb#(ba(aa(aa(ab(x1))))) → bb#(x1) (31)
bb#(ba(aa(aa(aa(x1))))) → ba#(aa(ab(bb(ba(x1))))) (32)
bb#(ba(aa(aa(aa(x1))))) → ab#(bb(ba(x1))) (33)
bb#(ba(aa(aa(aa(x1))))) → bb#(ba(x1)) (34)
bb#(ba(aa(aa(aa(x1))))) → ba#(x1) (35)
ab#(ba(aa(aa(ab(x1))))) → ab#(bb(bb(x1))) (36)
ab#(ba(aa(aa(ab(x1))))) → bb#(bb(x1)) (37)
ab#(ba(aa(aa(ab(x1))))) → bb#(x1) (38)
ab#(ba(aa(aa(aa(x1))))) → ab#(bb(ba(x1))) (39)
ab#(ba(aa(aa(aa(x1))))) → bb#(ba(x1)) (40)
ab#(ba(aa(aa(aa(x1))))) → ba#(x1) (41)

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.