Certification Problem

Input (TPDB SRS_Standard/Waldmann_19/random-554)

The rewrite relation of the following TRS is considered.

b(b(a(b(x1)))) → a(b(a(b(x1)))) (1)
a(a(a(a(x1)))) → b(b(b(b(x1)))) (2)
b(b(a(b(x1)))) → a(a(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(b(b(a(b(x1))))) → b(a(b(a(b(x1))))) (4)
a(b(b(a(b(x1))))) → a(a(b(a(b(x1))))) (5)
b(a(a(a(a(x1))))) → b(b(b(b(b(x1))))) (6)
a(a(a(a(a(x1))))) → a(b(b(b(b(x1))))) (7)
b(b(b(a(b(x1))))) → b(a(a(a(b(x1))))) (8)
a(b(b(a(b(x1))))) → a(a(a(a(b(x1))))) (9)

1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
bb(bb(ba(ab(bb(x1))))) → ba(ab(ba(ab(bb(x1))))) (10)
bb(bb(ba(ab(ba(x1))))) → ba(ab(ba(ab(ba(x1))))) (11)
ab(bb(ba(ab(bb(x1))))) → aa(ab(ba(ab(bb(x1))))) (12)
ab(bb(ba(ab(ba(x1))))) → aa(ab(ba(ab(ba(x1))))) (13)
ba(aa(aa(aa(ab(x1))))) → bb(bb(bb(bb(bb(x1))))) (14)
ba(aa(aa(aa(aa(x1))))) → bb(bb(bb(bb(ba(x1))))) (15)
aa(aa(aa(aa(ab(x1))))) → ab(bb(bb(bb(bb(x1))))) (16)
aa(aa(aa(aa(aa(x1))))) → ab(bb(bb(bb(ba(x1))))) (17)
bb(bb(ba(ab(bb(x1))))) → ba(aa(aa(ab(bb(x1))))) (18)
bb(bb(ba(ab(ba(x1))))) → ba(aa(aa(ab(ba(x1))))) (19)
ab(bb(ba(ab(bb(x1))))) → aa(aa(aa(ab(bb(x1))))) (20)
ab(bb(ba(ab(ba(x1))))) → aa(aa(aa(ab(ba(x1))))) (21)

1.1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
bb#(bb(ba(ab(bb(x1))))) → ba#(ab(ba(ab(bb(x1))))) (22)
bb#(bb(ba(ab(bb(x1))))) → ab#(ba(ab(bb(x1)))) (23)
bb#(bb(ba(ab(ba(x1))))) → ba#(ab(ba(ab(ba(x1))))) (24)
bb#(bb(ba(ab(ba(x1))))) → ab#(ba(ab(ba(x1)))) (25)
ab#(bb(ba(ab(bb(x1))))) → aa#(ab(ba(ab(bb(x1))))) (26)
ab#(bb(ba(ab(bb(x1))))) → ab#(ba(ab(bb(x1)))) (27)
ab#(bb(ba(ab(ba(x1))))) → aa#(ab(ba(ab(ba(x1))))) (28)
ab#(bb(ba(ab(ba(x1))))) → ab#(ba(ab(ba(x1)))) (29)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(bb(bb(x1))))) (30)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(bb(x1)))) (31)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(x1))) (32)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(x1)) (33)
ba#(aa(aa(aa(ab(x1))))) → bb#(x1) (34)
ba#(aa(aa(aa(aa(x1))))) → bb#(bb(bb(bb(ba(x1))))) (35)
ba#(aa(aa(aa(aa(x1))))) → bb#(bb(bb(ba(x1)))) (36)
ba#(aa(aa(aa(aa(x1))))) → bb#(bb(ba(x1))) (37)
ba#(aa(aa(aa(aa(x1))))) → bb#(ba(x1)) (38)
ba#(aa(aa(aa(aa(x1))))) → ba#(x1) (39)
aa#(aa(aa(aa(ab(x1))))) → ab#(bb(bb(bb(bb(x1))))) (40)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(bb(x1)))) (41)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(x1))) (42)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(x1)) (43)
aa#(aa(aa(aa(ab(x1))))) → bb#(x1) (44)
aa#(aa(aa(aa(aa(x1))))) → ab#(bb(bb(bb(ba(x1))))) (45)
aa#(aa(aa(aa(aa(x1))))) → bb#(bb(bb(ba(x1)))) (46)
aa#(aa(aa(aa(aa(x1))))) → bb#(bb(ba(x1))) (47)
aa#(aa(aa(aa(aa(x1))))) → bb#(ba(x1)) (48)
aa#(aa(aa(aa(aa(x1))))) → ba#(x1) (49)
bb#(bb(ba(ab(bb(x1))))) → ba#(aa(aa(ab(bb(x1))))) (50)
bb#(bb(ba(ab(bb(x1))))) → aa#(aa(ab(bb(x1)))) (51)
bb#(bb(ba(ab(bb(x1))))) → aa#(ab(bb(x1))) (52)
bb#(bb(ba(ab(ba(x1))))) → ba#(aa(aa(ab(ba(x1))))) (53)
bb#(bb(ba(ab(ba(x1))))) → aa#(aa(ab(ba(x1)))) (54)
bb#(bb(ba(ab(ba(x1))))) → aa#(ab(ba(x1))) (55)
ab#(bb(ba(ab(bb(x1))))) → aa#(aa(aa(ab(bb(x1))))) (56)
ab#(bb(ba(ab(bb(x1))))) → aa#(aa(ab(bb(x1)))) (57)
ab#(bb(ba(ab(bb(x1))))) → aa#(ab(bb(x1))) (58)
ab#(bb(ba(ab(ba(x1))))) → aa#(aa(aa(ab(ba(x1))))) (59)
ab#(bb(ba(ab(ba(x1))))) → aa#(aa(ab(ba(x1)))) (60)
ab#(bb(ba(ab(ba(x1))))) → aa#(ab(ba(x1))) (61)

1.1.1.1 Reduction Pair Processor

Using the linear polynomial interpretation over the naturals
[bb#(x1)] = 1 · x1
[bb(x1)] = 1 + 1 · x1
[ba(x1)] = 1 + 1 · x1
[ab(x1)] = 1 + 1 · x1
[ba#(x1)] = 1 · x1
[ab#(x1)] = 1 · x1
[aa#(x1)] = 1 · x1
[aa(x1)] = 1 + 1 · x1
the pairs
bb#(bb(ba(ab(bb(x1))))) → ab#(ba(ab(bb(x1)))) (23)
bb#(bb(ba(ab(ba(x1))))) → ab#(ba(ab(ba(x1)))) (25)
ab#(bb(ba(ab(bb(x1))))) → ab#(ba(ab(bb(x1)))) (27)
ab#(bb(ba(ab(ba(x1))))) → ab#(ba(ab(ba(x1)))) (29)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(bb(x1)))) (31)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(x1))) (32)
ba#(aa(aa(aa(ab(x1))))) → bb#(bb(x1)) (33)
ba#(aa(aa(aa(ab(x1))))) → bb#(x1) (34)
ba#(aa(aa(aa(aa(x1))))) → bb#(bb(bb(ba(x1)))) (36)
ba#(aa(aa(aa(aa(x1))))) → bb#(bb(ba(x1))) (37)
ba#(aa(aa(aa(aa(x1))))) → bb#(ba(x1)) (38)
ba#(aa(aa(aa(aa(x1))))) → ba#(x1) (39)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(bb(x1)))) (41)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(bb(x1))) (42)
aa#(aa(aa(aa(ab(x1))))) → bb#(bb(x1)) (43)
aa#(aa(aa(aa(ab(x1))))) → bb#(x1) (44)
aa#(aa(aa(aa(aa(x1))))) → bb#(bb(bb(ba(x1)))) (46)
aa#(aa(aa(aa(aa(x1))))) → bb#(bb(ba(x1))) (47)
aa#(aa(aa(aa(aa(x1))))) → bb#(ba(x1)) (48)
aa#(aa(aa(aa(aa(x1))))) → ba#(x1) (49)
bb#(bb(ba(ab(bb(x1))))) → aa#(aa(ab(bb(x1)))) (51)
bb#(bb(ba(ab(bb(x1))))) → aa#(ab(bb(x1))) (52)
bb#(bb(ba(ab(ba(x1))))) → aa#(aa(ab(ba(x1)))) (54)
bb#(bb(ba(ab(ba(x1))))) → aa#(ab(ba(x1))) (55)
ab#(bb(ba(ab(bb(x1))))) → aa#(aa(ab(bb(x1)))) (57)
ab#(bb(ba(ab(bb(x1))))) → aa#(ab(bb(x1))) (58)
ab#(bb(ba(ab(ba(x1))))) → aa#(aa(ab(ba(x1)))) (60)
ab#(bb(ba(ab(ba(x1))))) → aa#(ab(ba(x1))) (61)
could be deleted.

1.1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 2 components.