Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-66)

The relative rewrite relation R/S is considered where R is the following TRS

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

and S is the following TRS.

a(c(b(x1))) → b(b(c(x1))) (5)
a(c(b(x1))) → c(b(c(x1))) (6)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
b(a(c(x1))) → c(b(a(x1))) (7)
a(b(a(x1))) → a(a(c(x1))) (8)
c(c(c(x1))) → c(c(b(x1))) (9)
a(b(b(x1))) → b(b(b(x1))) (10)
b(c(a(x1))) → c(b(b(x1))) (11)
b(c(a(x1))) → c(b(c(x1))) (12)

1.1 Closure Under Flat Contexts

Using the flat contexts

{b(☐), a(☐), c(☐)}

We obtain the transformed TRS
a(b(a(x1))) → a(a(c(x1))) (8)
c(c(c(x1))) → c(c(b(x1))) (9)
b(b(a(c(x1)))) → b(c(b(a(x1)))) (13)
a(b(a(c(x1)))) → a(c(b(a(x1)))) (14)
c(b(a(c(x1)))) → c(c(b(a(x1)))) (15)
b(a(b(b(x1)))) → b(b(b(b(x1)))) (16)
a(a(b(b(x1)))) → a(b(b(b(x1)))) (17)
c(a(b(b(x1)))) → c(b(b(b(x1)))) (18)
b(b(c(a(x1)))) → b(c(b(b(x1)))) (19)
a(b(c(a(x1)))) → a(c(b(b(x1)))) (20)
c(b(c(a(x1)))) → c(c(b(b(x1)))) (21)
b(b(c(a(x1)))) → b(c(b(c(x1)))) (22)
a(b(c(a(x1)))) → a(c(b(c(x1)))) (23)
c(b(c(a(x1)))) → c(c(b(c(x1)))) (24)

1.1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
ab(ba(aa(x1))) → aa(ac(ca(x1))) (25)
ab(ba(ab(x1))) → aa(ac(cb(x1))) (26)
ab(ba(ac(x1))) → aa(ac(cc(x1))) (27)
cc(cc(ca(x1))) → cc(cb(ba(x1))) (28)
cc(cc(cb(x1))) → cc(cb(bb(x1))) (29)
cc(cc(cc(x1))) → cc(cb(bc(x1))) (30)
bb(ba(ac(ca(x1)))) → bc(cb(ba(aa(x1)))) (31)
bb(ba(ac(cb(x1)))) → bc(cb(ba(ab(x1)))) (32)
bb(ba(ac(cc(x1)))) → bc(cb(ba(ac(x1)))) (33)
ab(ba(ac(ca(x1)))) → ac(cb(ba(aa(x1)))) (34)
ab(ba(ac(cb(x1)))) → ac(cb(ba(ab(x1)))) (35)
ab(ba(ac(cc(x1)))) → ac(cb(ba(ac(x1)))) (36)
cb(ba(ac(ca(x1)))) → cc(cb(ba(aa(x1)))) (37)
cb(ba(ac(cb(x1)))) → cc(cb(ba(ab(x1)))) (38)
cb(ba(ac(cc(x1)))) → cc(cb(ba(ac(x1)))) (39)
ba(ab(bb(ba(x1)))) → bb(bb(bb(ba(x1)))) (40)
ba(ab(bb(bb(x1)))) → bb(bb(bb(bb(x1)))) (41)
ba(ab(bb(bc(x1)))) → bb(bb(bb(bc(x1)))) (42)
aa(ab(bb(ba(x1)))) → ab(bb(bb(ba(x1)))) (43)
aa(ab(bb(bb(x1)))) → ab(bb(bb(bb(x1)))) (44)
aa(ab(bb(bc(x1)))) → ab(bb(bb(bc(x1)))) (45)
ca(ab(bb(ba(x1)))) → cb(bb(bb(ba(x1)))) (46)
ca(ab(bb(bb(x1)))) → cb(bb(bb(bb(x1)))) (47)
ca(ab(bb(bc(x1)))) → cb(bb(bb(bc(x1)))) (48)
bb(bc(ca(aa(x1)))) → bc(cb(bb(ba(x1)))) (49)
bb(bc(ca(ab(x1)))) → bc(cb(bb(bb(x1)))) (50)
bb(bc(ca(ac(x1)))) → bc(cb(bb(bc(x1)))) (51)
ab(bc(ca(aa(x1)))) → ac(cb(bb(ba(x1)))) (52)
ab(bc(ca(ab(x1)))) → ac(cb(bb(bb(x1)))) (53)
ab(bc(ca(ac(x1)))) → ac(cb(bb(bc(x1)))) (54)
cb(bc(ca(aa(x1)))) → cc(cb(bb(ba(x1)))) (55)
cb(bc(ca(ab(x1)))) → cc(cb(bb(bb(x1)))) (56)
cb(bc(ca(ac(x1)))) → cc(cb(bb(bc(x1)))) (57)
bb(bc(ca(aa(x1)))) → bc(cb(bc(ca(x1)))) (58)
bb(bc(ca(ab(x1)))) → bc(cb(bc(cb(x1)))) (59)
bb(bc(ca(ac(x1)))) → bc(cb(bc(cc(x1)))) (60)
ab(bc(ca(aa(x1)))) → ac(cb(bc(ca(x1)))) (61)
ab(bc(ca(ab(x1)))) → ac(cb(bc(cb(x1)))) (62)
ab(bc(ca(ac(x1)))) → ac(cb(bc(cc(x1)))) (63)
cb(bc(ca(aa(x1)))) → cc(cb(bc(ca(x1)))) (64)
cb(bc(ca(ab(x1)))) → cc(cb(bc(cb(x1)))) (65)
cb(bc(ca(ac(x1)))) → cc(cb(bc(cc(x1)))) (66)

1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[ab(x1)] = 1 · x1
[ba(x1)] = 1 + 1 · x1
[aa(x1)] = 1 + 1 · x1
[ac(x1)] = 1 · x1
[ca(x1)] = 1 + 1 · x1
[cb(x1)] = 1 · x1
[cc(x1)] = 1 · x1
[bb(x1)] = 1 · x1
[bc(x1)] = 1 · x1
all of the following rules can be deleted.
ba(ab(bb(ba(x1)))) → bb(bb(bb(ba(x1)))) (40)
ba(ab(bb(bb(x1)))) → bb(bb(bb(bb(x1)))) (41)
ba(ab(bb(bc(x1)))) → bb(bb(bb(bc(x1)))) (42)
aa(ab(bb(ba(x1)))) → ab(bb(bb(ba(x1)))) (43)
aa(ab(bb(bb(x1)))) → ab(bb(bb(bb(x1)))) (44)
aa(ab(bb(bc(x1)))) → ab(bb(bb(bc(x1)))) (45)
ca(ab(bb(ba(x1)))) → cb(bb(bb(ba(x1)))) (46)
ca(ab(bb(bb(x1)))) → cb(bb(bb(bb(x1)))) (47)
ca(ab(bb(bc(x1)))) → cb(bb(bb(bc(x1)))) (48)
bb(bc(ca(aa(x1)))) → bc(cb(bb(ba(x1)))) (49)
bb(bc(ca(ab(x1)))) → bc(cb(bb(bb(x1)))) (50)
bb(bc(ca(ac(x1)))) → bc(cb(bb(bc(x1)))) (51)
ab(bc(ca(aa(x1)))) → ac(cb(bb(ba(x1)))) (52)
ab(bc(ca(ab(x1)))) → ac(cb(bb(bb(x1)))) (53)
ab(bc(ca(ac(x1)))) → ac(cb(bb(bc(x1)))) (54)
cb(bc(ca(aa(x1)))) → cc(cb(bb(ba(x1)))) (55)
cb(bc(ca(ab(x1)))) → cc(cb(bb(bb(x1)))) (56)
cb(bc(ca(ac(x1)))) → cc(cb(bb(bc(x1)))) (57)
bb(bc(ca(aa(x1)))) → bc(cb(bc(ca(x1)))) (58)
bb(bc(ca(ab(x1)))) → bc(cb(bc(cb(x1)))) (59)
bb(bc(ca(ac(x1)))) → bc(cb(bc(cc(x1)))) (60)
ab(bc(ca(aa(x1)))) → ac(cb(bc(ca(x1)))) (61)
ab(bc(ca(ab(x1)))) → ac(cb(bc(cb(x1)))) (62)
ab(bc(ca(ac(x1)))) → ac(cb(bc(cc(x1)))) (63)
cb(bc(ca(aa(x1)))) → cc(cb(bc(ca(x1)))) (64)
cb(bc(ca(ab(x1)))) → cc(cb(bc(cb(x1)))) (65)
cb(bc(ca(ac(x1)))) → cc(cb(bc(cc(x1)))) (66)

1.1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[ab(x1)] = 1 · x1
[ba(x1)] = 1 · x1 + 2
[aa(x1)] = 1 · x1
[ac(x1)] = 1 · x1 + 1
[ca(x1)] = 1 · x1 + 1
[cb(x1)] = 1 · x1
[cc(x1)] = 1 · x1 + 1
[bb(x1)] = 1 · x1
[bc(x1)] = 1 · x1
all of the following rules can be deleted.
ab(ba(ab(x1))) → aa(ac(cb(x1))) (26)
ab(ba(ac(x1))) → aa(ac(cc(x1))) (27)
cc(cc(cb(x1))) → cc(cb(bb(x1))) (29)
cc(cc(cc(x1))) → cc(cb(bc(x1))) (30)
bb(ba(ac(ca(x1)))) → bc(cb(ba(aa(x1)))) (31)
bb(ba(ac(cb(x1)))) → bc(cb(ba(ab(x1)))) (32)
bb(ba(ac(cc(x1)))) → bc(cb(ba(ac(x1)))) (33)
ab(ba(ac(ca(x1)))) → ac(cb(ba(aa(x1)))) (34)
cb(ba(ac(ca(x1)))) → cc(cb(ba(aa(x1)))) (37)

1.1.1.1.1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
cc#(cc(ca(x1))) → cc#(cb(ba(x1))) (67)
cc#(cc(ca(x1))) → cb#(ba(x1)) (68)
ab#(ba(ac(cb(x1)))) → cb#(ba(ab(x1))) (69)
ab#(ba(ac(cb(x1)))) → ab#(x1) (70)
ab#(ba(ac(cc(x1)))) → cb#(ba(ac(x1))) (71)
cb#(ba(ac(cb(x1)))) → cc#(cb(ba(ab(x1)))) (72)
cb#(ba(ac(cb(x1)))) → cb#(ba(ab(x1))) (73)
cb#(ba(ac(cb(x1)))) → ab#(x1) (74)
cb#(ba(ac(cc(x1)))) → cc#(cb(ba(ac(x1)))) (75)
cb#(ba(ac(cc(x1)))) → cb#(ba(ac(x1))) (76)

1.1.1.1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.