Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-148)

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

c(c(b(x1))) → b(b(b(x1))) (1)
c(a(c(x1))) → b(a(a(x1))) (2)
c(c(c(x1))) → a(a(b(x1))) (3)
c(b(c(x1))) → c(b(b(x1))) (4)
c(a(c(x1))) → b(b(c(x1))) (5)
c(b(c(x1))) → c(c(b(x1))) (6)

and S is the following TRS.

a(b(b(x1))) → b(a(c(x1))) (7)

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(c(c(x1))) → b(b(b(x1))) (8)
c(a(c(x1))) → a(a(b(x1))) (9)
c(c(c(x1))) → b(a(a(x1))) (10)
c(b(c(x1))) → b(b(c(x1))) (11)
c(a(c(x1))) → c(b(b(x1))) (12)
c(b(c(x1))) → b(c(c(x1))) (13)
b(b(a(x1))) → c(a(b(x1))) (14)

1.1 Closure Under Flat Contexts

Using the flat contexts

{b(☐), c(☐), a(☐)}

We obtain the transformed TRS
b(c(c(x1))) → b(b(b(x1))) (8)
c(a(c(x1))) → c(b(b(x1))) (12)
b(c(a(c(x1)))) → b(a(a(b(x1)))) (15)
c(c(a(c(x1)))) → c(a(a(b(x1)))) (16)
a(c(a(c(x1)))) → a(a(a(b(x1)))) (17)
b(c(c(c(x1)))) → b(b(a(a(x1)))) (18)
c(c(c(c(x1)))) → c(b(a(a(x1)))) (19)
a(c(c(c(x1)))) → a(b(a(a(x1)))) (20)
b(c(b(c(x1)))) → b(b(b(c(x1)))) (21)
c(c(b(c(x1)))) → c(b(b(c(x1)))) (22)
a(c(b(c(x1)))) → a(b(b(c(x1)))) (23)
b(c(b(c(x1)))) → b(b(c(c(x1)))) (24)
c(c(b(c(x1)))) → c(b(c(c(x1)))) (25)
a(c(b(c(x1)))) → a(b(c(c(x1)))) (26)
b(b(b(a(x1)))) → b(c(a(b(x1)))) (27)
c(b(b(a(x1)))) → c(c(a(b(x1)))) (28)
a(b(b(a(x1)))) → a(c(a(b(x1)))) (29)

1.1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
bc(cc(cb(x1))) → bb(bb(bb(x1))) (30)
bc(cc(cc(x1))) → bb(bb(bc(x1))) (31)
bc(cc(ca(x1))) → bb(bb(ba(x1))) (32)
ca(ac(cb(x1))) → cb(bb(bb(x1))) (33)
ca(ac(cc(x1))) → cb(bb(bc(x1))) (34)
ca(ac(ca(x1))) → cb(bb(ba(x1))) (35)
bc(ca(ac(cb(x1)))) → ba(aa(ab(bb(x1)))) (36)
bc(ca(ac(cc(x1)))) → ba(aa(ab(bc(x1)))) (37)
bc(ca(ac(ca(x1)))) → ba(aa(ab(ba(x1)))) (38)
cc(ca(ac(cb(x1)))) → ca(aa(ab(bb(x1)))) (39)
cc(ca(ac(cc(x1)))) → ca(aa(ab(bc(x1)))) (40)
cc(ca(ac(ca(x1)))) → ca(aa(ab(ba(x1)))) (41)
ac(ca(ac(cb(x1)))) → aa(aa(ab(bb(x1)))) (42)
ac(ca(ac(cc(x1)))) → aa(aa(ab(bc(x1)))) (43)
ac(ca(ac(ca(x1)))) → aa(aa(ab(ba(x1)))) (44)
bc(cc(cc(cb(x1)))) → bb(ba(aa(ab(x1)))) (45)
bc(cc(cc(cc(x1)))) → bb(ba(aa(ac(x1)))) (46)
bc(cc(cc(ca(x1)))) → bb(ba(aa(aa(x1)))) (47)
cc(cc(cc(cb(x1)))) → cb(ba(aa(ab(x1)))) (48)
cc(cc(cc(cc(x1)))) → cb(ba(aa(ac(x1)))) (49)
cc(cc(cc(ca(x1)))) → cb(ba(aa(aa(x1)))) (50)
ac(cc(cc(cb(x1)))) → ab(ba(aa(ab(x1)))) (51)
ac(cc(cc(cc(x1)))) → ab(ba(aa(ac(x1)))) (52)
ac(cc(cc(ca(x1)))) → ab(ba(aa(aa(x1)))) (53)
bc(cb(bc(cb(x1)))) → bb(bb(bc(cb(x1)))) (54)
bc(cb(bc(cc(x1)))) → bb(bb(bc(cc(x1)))) (55)
bc(cb(bc(ca(x1)))) → bb(bb(bc(ca(x1)))) (56)
cc(cb(bc(cb(x1)))) → cb(bb(bc(cb(x1)))) (57)
cc(cb(bc(cc(x1)))) → cb(bb(bc(cc(x1)))) (58)
cc(cb(bc(ca(x1)))) → cb(bb(bc(ca(x1)))) (59)
ac(cb(bc(cb(x1)))) → ab(bb(bc(cb(x1)))) (60)
ac(cb(bc(cc(x1)))) → ab(bb(bc(cc(x1)))) (61)
ac(cb(bc(ca(x1)))) → ab(bb(bc(ca(x1)))) (62)
bc(cb(bc(cb(x1)))) → bb(bc(cc(cb(x1)))) (63)
bc(cb(bc(cc(x1)))) → bb(bc(cc(cc(x1)))) (64)
bc(cb(bc(ca(x1)))) → bb(bc(cc(ca(x1)))) (65)
cc(cb(bc(cb(x1)))) → cb(bc(cc(cb(x1)))) (66)
cc(cb(bc(cc(x1)))) → cb(bc(cc(cc(x1)))) (67)
cc(cb(bc(ca(x1)))) → cb(bc(cc(ca(x1)))) (68)
ac(cb(bc(cb(x1)))) → ab(bc(cc(cb(x1)))) (69)
ac(cb(bc(cc(x1)))) → ab(bc(cc(cc(x1)))) (70)
ac(cb(bc(ca(x1)))) → ab(bc(cc(ca(x1)))) (71)
bb(bb(ba(ab(x1)))) → bc(ca(ab(bb(x1)))) (72)
bb(bb(ba(ac(x1)))) → bc(ca(ab(bc(x1)))) (73)
bb(bb(ba(aa(x1)))) → bc(ca(ab(ba(x1)))) (74)
cb(bb(ba(ab(x1)))) → cc(ca(ab(bb(x1)))) (75)
cb(bb(ba(ac(x1)))) → cc(ca(ab(bc(x1)))) (76)
cb(bb(ba(aa(x1)))) → cc(ca(ab(ba(x1)))) (77)
ab(bb(ba(ab(x1)))) → ac(ca(ab(bb(x1)))) (78)
ab(bb(ba(ac(x1)))) → ac(ca(ab(bc(x1)))) (79)
ab(bb(ba(aa(x1)))) → ac(ca(ab(ba(x1)))) (80)

1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[bc(x1)] = 3 + 1 · x1
[cc(x1)] = 4 + 2 · x1
[cb(x1)] = 4 · x1
[bb(x1)] = 2 · x1
[ca(x1)] = 4 · x1
[ba(x1)] = 1 + 2 · x1
[ac(x1)] = 3 + 1 · x1
[aa(x1)] = 1 + 2 · x1
[ab(x1)] = 2 · x1
all of the following rules can be deleted.
bc(cc(cb(x1))) → bb(bb(bb(x1))) (30)
bc(cc(cc(x1))) → bb(bb(bc(x1))) (31)
bc(cc(ca(x1))) → bb(bb(ba(x1))) (32)
ca(ac(cb(x1))) → cb(bb(bb(x1))) (33)
ca(ac(cc(x1))) → cb(bb(bc(x1))) (34)
ca(ac(ca(x1))) → cb(bb(ba(x1))) (35)
bc(ca(ac(cb(x1)))) → ba(aa(ab(bb(x1)))) (36)
bc(ca(ac(cc(x1)))) → ba(aa(ab(bc(x1)))) (37)
bc(ca(ac(ca(x1)))) → ba(aa(ab(ba(x1)))) (38)
cc(ca(ac(cb(x1)))) → ca(aa(ab(bb(x1)))) (39)
cc(ca(ac(cc(x1)))) → ca(aa(ab(bc(x1)))) (40)
cc(ca(ac(ca(x1)))) → ca(aa(ab(ba(x1)))) (41)
ac(ca(ac(cb(x1)))) → aa(aa(ab(bb(x1)))) (42)
ac(ca(ac(cc(x1)))) → aa(aa(ab(bc(x1)))) (43)
ac(ca(ac(ca(x1)))) → aa(aa(ab(ba(x1)))) (44)
bc(cc(cc(cb(x1)))) → bb(ba(aa(ab(x1)))) (45)
bc(cc(cc(cc(x1)))) → bb(ba(aa(ac(x1)))) (46)
bc(cc(cc(ca(x1)))) → bb(ba(aa(aa(x1)))) (47)
cc(cc(cc(cb(x1)))) → cb(ba(aa(ab(x1)))) (48)
ac(cc(cc(cb(x1)))) → ab(ba(aa(ab(x1)))) (51)
ac(cc(cc(cc(x1)))) → ab(ba(aa(ac(x1)))) (52)
ac(cc(cc(ca(x1)))) → ab(ba(aa(aa(x1)))) (53)
bc(cb(bc(cb(x1)))) → bb(bb(bc(cb(x1)))) (54)
bc(cb(bc(cc(x1)))) → bb(bb(bc(cc(x1)))) (55)
bc(cb(bc(ca(x1)))) → bb(bb(bc(ca(x1)))) (56)
cc(cb(bc(cb(x1)))) → cb(bb(bc(cb(x1)))) (57)
cc(cb(bc(cc(x1)))) → cb(bb(bc(cc(x1)))) (58)
cc(cb(bc(ca(x1)))) → cb(bb(bc(ca(x1)))) (59)
ac(cb(bc(cb(x1)))) → ab(bb(bc(cb(x1)))) (60)
ac(cb(bc(cc(x1)))) → ab(bb(bc(cc(x1)))) (61)
ac(cb(bc(ca(x1)))) → ab(bb(bc(ca(x1)))) (62)
bc(cb(bc(cb(x1)))) → bb(bc(cc(cb(x1)))) (63)
bc(cb(bc(cc(x1)))) → bb(bc(cc(cc(x1)))) (64)
bc(cb(bc(ca(x1)))) → bb(bc(cc(ca(x1)))) (65)
ac(cb(bc(cb(x1)))) → ab(bc(cc(cb(x1)))) (69)
ac(cb(bc(cc(x1)))) → ab(bc(cc(cc(x1)))) (70)
ac(cb(bc(ca(x1)))) → ab(bc(cc(ca(x1)))) (71)
bb(bb(ba(ab(x1)))) → bc(ca(ab(bb(x1)))) (72)
bb(bb(ba(ac(x1)))) → bc(ca(ab(bc(x1)))) (73)
bb(bb(ba(aa(x1)))) → bc(ca(ab(ba(x1)))) (74)
cb(bb(ba(ab(x1)))) → cc(ca(ab(bb(x1)))) (75)
cb(bb(ba(ac(x1)))) → cc(ca(ab(bc(x1)))) (76)
cb(bb(ba(aa(x1)))) → cc(ca(ab(ba(x1)))) (77)
ab(bb(ba(ab(x1)))) → ac(ca(ab(bb(x1)))) (78)
ab(bb(ba(ac(x1)))) → ac(ca(ab(bc(x1)))) (79)
ab(bb(ba(aa(x1)))) → ac(ca(ab(ba(x1)))) (80)

1.1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[cc(x1)] = 1 · x1 + 1
[cb(x1)] = 1 · x1
[ba(x1)] = 1 · x1
[aa(x1)] = 1 · x1
[ac(x1)] = 1 · x1
[ca(x1)] = 1 · x1
[bc(x1)] = 1 · x1
all of the following rules can be deleted.
cc(cc(cc(cc(x1)))) → cb(ba(aa(ac(x1)))) (49)
cc(cc(cc(ca(x1)))) → cb(ba(aa(aa(x1)))) (50)

1.1.1.1.1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
cc#(cb(bc(cb(x1)))) → cc#(cb(x1)) (81)
cc#(cb(bc(cc(x1)))) → cc#(cc(x1)) (82)
cc#(cb(bc(ca(x1)))) → cc#(ca(x1)) (83)

1.1.1.1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.