Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-42)

The rewrite relation of the following TRS is considered.

a(a(c(x1))) → b(a(a(x1))) (1)
b(c(a(x1))) → a(a(a(x1))) (2)
c(a(a(x1))) → b(c(a(x1))) (3)
c(c(a(x1))) → c(a(c(x1))) (4)
a(b(c(x1))) → a(c(b(x1))) (5)
a(b(b(x1))) → b(a(c(x1))) (6)
a(a(c(x1))) → a(c(a(x1))) (7)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by matchbox @ termCOMP 2023)

1 Split

We split R in the relative problem D/R-D and R-D, where the rules D

a(a(c(x1))) → b(a(a(x1))) (1)
b(c(a(x1))) → a(a(a(x1))) (2)
c(a(a(x1))) → b(c(a(x1))) (3)
a(b(c(x1))) → a(c(b(x1))) (5)
a(b(b(x1))) → b(a(c(x1))) (6)
are deleted.

1.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(a(a(c(x1)))) → c(b(a(a(x1)))) (8)
c(b(c(a(x1)))) → c(a(a(a(x1)))) (9)
c(c(a(a(x1)))) → c(b(c(a(x1)))) (10)
c(a(b(c(x1)))) → c(a(c(b(x1)))) (11)
c(a(b(b(x1)))) → c(b(a(c(x1)))) (12)
b(a(a(c(x1)))) → b(b(a(a(x1)))) (13)
b(b(c(a(x1)))) → b(a(a(a(x1)))) (14)
b(c(a(a(x1)))) → b(b(c(a(x1)))) (15)
b(a(b(c(x1)))) → b(a(c(b(x1)))) (16)
b(a(b(b(x1)))) → b(b(a(c(x1)))) (17)
a(a(a(c(x1)))) → a(b(a(a(x1)))) (18)
a(b(c(a(x1)))) → a(a(a(a(x1)))) (19)
a(c(a(a(x1)))) → a(b(c(a(x1)))) (20)
a(a(b(c(x1)))) → a(a(c(b(x1)))) (21)
a(a(b(b(x1)))) → a(b(a(c(x1)))) (22)
c(c(c(a(x1)))) → c(c(a(c(x1)))) (23)
c(a(a(c(x1)))) → c(a(c(a(x1)))) (24)
b(c(c(a(x1)))) → b(c(a(c(x1)))) (25)
b(a(a(c(x1)))) → b(a(c(a(x1)))) (26)
a(c(c(a(x1)))) → a(c(a(c(x1)))) (27)
a(a(a(c(x1)))) → a(a(c(a(x1)))) (28)

1.1.1 Semantic Labeling

The following interpretations form a model of the rules.

As carrier we take the set {0,1,2}. Symbols are labeled by the interpretation of their arguments using the interpretations (modulo 3):

[c(x1)] = 3x1 + 0
[b(x1)] = 3x1 + 1
[a(x1)] = 3x1 + 2

We obtain the labeled TRS
a2(a2(a0(c2(x1)))) → a1(b2(a2(a2(x1)))) (29)
a2(a2(a0(c0(x1)))) → a1(b2(a2(a0(x1)))) (30)
a2(a2(a0(c1(x1)))) → a1(b2(a2(a1(x1)))) (31)
c2(a2(a0(c2(x1)))) → c1(b2(a2(a2(x1)))) (32)
c2(a2(a0(c0(x1)))) → c1(b2(a2(a0(x1)))) (33)
c2(a2(a0(c1(x1)))) → c1(b2(a2(a1(x1)))) (34)
b2(a2(a0(c2(x1)))) → b1(b2(a2(a2(x1)))) (35)
b2(a2(a0(c0(x1)))) → b1(b2(a2(a0(x1)))) (36)
b2(a2(a0(c1(x1)))) → b1(b2(a2(a1(x1)))) (37)
a1(b0(c2(a2(x1)))) → a2(a2(a2(a2(x1)))) (38)
a1(b0(c2(a0(x1)))) → a2(a2(a2(a0(x1)))) (39)
a1(b0(c2(a1(x1)))) → a2(a2(a2(a1(x1)))) (40)
c1(b0(c2(a2(x1)))) → c2(a2(a2(a2(x1)))) (41)
c1(b0(c2(a0(x1)))) → c2(a2(a2(a0(x1)))) (42)
c1(b0(c2(a1(x1)))) → c2(a2(a2(a1(x1)))) (43)
b1(b0(c2(a2(x1)))) → b2(a2(a2(a2(x1)))) (44)
b1(b0(c2(a0(x1)))) → b2(a2(a2(a0(x1)))) (45)
b1(b0(c2(a1(x1)))) → b2(a2(a2(a1(x1)))) (46)
a0(c2(a2(a2(x1)))) → a1(b0(c2(a2(x1)))) (47)
a0(c2(a2(a0(x1)))) → a1(b0(c2(a0(x1)))) (48)
a0(c2(a2(a1(x1)))) → a1(b0(c2(a1(x1)))) (49)
c0(c2(a2(a2(x1)))) → c1(b0(c2(a2(x1)))) (50)
c0(c2(a2(a0(x1)))) → c1(b0(c2(a0(x1)))) (51)
c0(c2(a2(a1(x1)))) → c1(b0(c2(a1(x1)))) (52)
b0(c2(a2(a2(x1)))) → b1(b0(c2(a2(x1)))) (53)
b0(c2(a2(a0(x1)))) → b1(b0(c2(a0(x1)))) (54)
b0(c2(a2(a1(x1)))) → b1(b0(c2(a1(x1)))) (55)
a2(a1(b0(c2(x1)))) → a2(a0(c1(b2(x1)))) (56)
a2(a1(b0(c0(x1)))) → a2(a0(c1(b0(x1)))) (57)
a2(a1(b0(c1(x1)))) → a2(a0(c1(b1(x1)))) (58)
c2(a1(b0(c2(x1)))) → c2(a0(c1(b2(x1)))) (59)
c2(a1(b0(c0(x1)))) → c2(a0(c1(b0(x1)))) (60)
c2(a1(b0(c1(x1)))) → c2(a0(c1(b1(x1)))) (61)
b2(a1(b0(c2(x1)))) → b2(a0(c1(b2(x1)))) (62)
b2(a1(b0(c0(x1)))) → b2(a0(c1(b0(x1)))) (63)
b2(a1(b0(c1(x1)))) → b2(a0(c1(b1(x1)))) (64)
a2(a1(b1(b2(x1)))) → a1(b2(a0(c2(x1)))) (65)
a2(a1(b1(b0(x1)))) → a1(b2(a0(c0(x1)))) (66)
a2(a1(b1(b1(x1)))) → a1(b2(a0(c1(x1)))) (67)
c2(a1(b1(b2(x1)))) → c1(b2(a0(c2(x1)))) (68)
c2(a1(b1(b0(x1)))) → c1(b2(a0(c0(x1)))) (69)
c2(a1(b1(b1(x1)))) → c1(b2(a0(c1(x1)))) (70)
b2(a1(b1(b2(x1)))) → b1(b2(a0(c2(x1)))) (71)
b2(a1(b1(b0(x1)))) → b1(b2(a0(c0(x1)))) (72)
b2(a1(b1(b1(x1)))) → b1(b2(a0(c1(x1)))) (73)
a0(c0(c2(a2(x1)))) → a0(c2(a0(c2(x1)))) (74)
a0(c0(c2(a0(x1)))) → a0(c2(a0(c0(x1)))) (75)
a0(c0(c2(a1(x1)))) → a0(c2(a0(c1(x1)))) (76)
c0(c0(c2(a2(x1)))) → c0(c2(a0(c2(x1)))) (77)
c0(c0(c2(a0(x1)))) → c0(c2(a0(c0(x1)))) (78)
c0(c0(c2(a1(x1)))) → c0(c2(a0(c1(x1)))) (79)
b0(c0(c2(a2(x1)))) → b0(c2(a0(c2(x1)))) (80)
b0(c0(c2(a0(x1)))) → b0(c2(a0(c0(x1)))) (81)
b0(c0(c2(a1(x1)))) → b0(c2(a0(c1(x1)))) (82)
a2(a2(a0(c2(x1)))) → a2(a0(c2(a2(x1)))) (83)
a2(a2(a0(c0(x1)))) → a2(a0(c2(a0(x1)))) (84)
a2(a2(a0(c1(x1)))) → a2(a0(c2(a1(x1)))) (85)
c2(a2(a0(c2(x1)))) → c2(a0(c2(a2(x1)))) (86)
c2(a2(a0(c0(x1)))) → c2(a0(c2(a0(x1)))) (87)
c2(a2(a0(c1(x1)))) → c2(a0(c2(a1(x1)))) (88)
b2(a2(a0(c2(x1)))) → b2(a0(c2(a2(x1)))) (89)
b2(a2(a0(c0(x1)))) → b2(a0(c2(a0(x1)))) (90)
b2(a2(a0(c1(x1)))) → b2(a0(c2(a1(x1)))) (91)

1.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
c2(a0(a2(a2(x1)))) → a2(a2(b2(a1(x1)))) (92)
c0(a0(a2(a2(x1)))) → a0(a2(b2(a1(x1)))) (93)
c1(a0(a2(a2(x1)))) → a1(a2(b2(a1(x1)))) (94)
c2(a0(a2(c2(x1)))) → a2(a2(b2(c1(x1)))) (95)
c0(a0(a2(c2(x1)))) → a0(a2(b2(c1(x1)))) (96)
c1(a0(a2(c2(x1)))) → a1(a2(b2(c1(x1)))) (97)
c2(a0(a2(b2(x1)))) → a2(a2(b2(b1(x1)))) (98)
c0(a0(a2(b2(x1)))) → a0(a2(b2(b1(x1)))) (99)
c1(a0(a2(b2(x1)))) → a1(a2(b2(b1(x1)))) (100)
a2(c2(b0(a1(x1)))) → a2(a2(a2(a2(x1)))) (101)
a0(c2(b0(a1(x1)))) → a0(a2(a2(a2(x1)))) (102)
a1(c2(b0(a1(x1)))) → a1(a2(a2(a2(x1)))) (103)
a2(c2(b0(c1(x1)))) → a2(a2(a2(c2(x1)))) (104)
a0(c2(b0(c1(x1)))) → a0(a2(a2(c2(x1)))) (105)
a1(c2(b0(c1(x1)))) → a1(a2(a2(c2(x1)))) (106)
a2(c2(b0(b1(x1)))) → a2(a2(a2(b2(x1)))) (107)
a0(c2(b0(b1(x1)))) → a0(a2(a2(b2(x1)))) (108)
a1(c2(b0(b1(x1)))) → a1(a2(a2(b2(x1)))) (109)
a2(a2(c2(a0(x1)))) → a2(c2(b0(a1(x1)))) (110)
a0(a2(c2(a0(x1)))) → a0(c2(b0(a1(x1)))) (111)
a1(a2(c2(a0(x1)))) → a1(c2(b0(a1(x1)))) (112)
a2(a2(c2(c0(x1)))) → a2(c2(b0(c1(x1)))) (113)
a0(a2(c2(c0(x1)))) → a0(c2(b0(c1(x1)))) (114)
a1(a2(c2(c0(x1)))) → a1(c2(b0(c1(x1)))) (115)
a2(a2(c2(b0(x1)))) → a2(c2(b0(b1(x1)))) (116)
a0(a2(c2(b0(x1)))) → a0(c2(b0(b1(x1)))) (117)
a1(a2(c2(b0(x1)))) → a1(c2(b0(b1(x1)))) (118)
c2(b0(a1(a2(x1)))) → b2(c1(a0(a2(x1)))) (119)
c0(b0(a1(a2(x1)))) → b0(c1(a0(a2(x1)))) (120)
c1(b0(a1(a2(x1)))) → b1(c1(a0(a2(x1)))) (121)
c2(b0(a1(c2(x1)))) → b2(c1(a0(c2(x1)))) (122)
c0(b0(a1(c2(x1)))) → b0(c1(a0(c2(x1)))) (123)
c1(b0(a1(c2(x1)))) → b1(c1(a0(c2(x1)))) (124)
c2(b0(a1(b2(x1)))) → b2(c1(a0(b2(x1)))) (125)
c0(b0(a1(b2(x1)))) → b0(c1(a0(b2(x1)))) (126)
c1(b0(a1(b2(x1)))) → b1(c1(a0(b2(x1)))) (127)
b2(b1(a1(a2(x1)))) → c2(a0(b2(a1(x1)))) (128)
b0(b1(a1(a2(x1)))) → c0(a0(b2(a1(x1)))) (129)
b1(b1(a1(a2(x1)))) → c1(a0(b2(a1(x1)))) (130)
b2(b1(a1(c2(x1)))) → c2(a0(b2(c1(x1)))) (131)
b0(b1(a1(c2(x1)))) → c0(a0(b2(c1(x1)))) (132)
b1(b1(a1(c2(x1)))) → c1(a0(b2(c1(x1)))) (133)
b2(b1(a1(b2(x1)))) → c2(a0(b2(b1(x1)))) (134)
b0(b1(a1(b2(x1)))) → c0(a0(b2(b1(x1)))) (135)
b1(b1(a1(b2(x1)))) → c1(a0(b2(b1(x1)))) (136)
a2(c2(c0(a0(x1)))) → c2(a0(c2(a0(x1)))) (137)
a0(c2(c0(a0(x1)))) → c0(a0(c2(a0(x1)))) (138)
a1(c2(c0(a0(x1)))) → c1(a0(c2(a0(x1)))) (139)
a2(c2(c0(c0(x1)))) → c2(a0(c2(c0(x1)))) (140)
a0(c2(c0(c0(x1)))) → c0(a0(c2(c0(x1)))) (141)
a1(c2(c0(c0(x1)))) → c1(a0(c2(c0(x1)))) (142)
a2(c2(c0(b0(x1)))) → c2(a0(c2(b0(x1)))) (143)
a0(c2(c0(b0(x1)))) → c0(a0(c2(b0(x1)))) (144)
a1(c2(c0(b0(x1)))) → c1(a0(c2(b0(x1)))) (145)
c2(a0(a2(a2(x1)))) → a2(c2(a0(a2(x1)))) (146)
c0(a0(a2(a2(x1)))) → a0(c2(a0(a2(x1)))) (147)
c1(a0(a2(a2(x1)))) → a1(c2(a0(a2(x1)))) (148)
c2(a0(a2(c2(x1)))) → a2(c2(a0(c2(x1)))) (149)
c0(a0(a2(c2(x1)))) → a0(c2(a0(c2(x1)))) (150)
c1(a0(a2(c2(x1)))) → a1(c2(a0(c2(x1)))) (151)
c2(a0(a2(b2(x1)))) → a2(c2(a0(b2(x1)))) (152)
c0(a0(a2(b2(x1)))) → a0(c2(a0(b2(x1)))) (153)
c1(a0(a2(b2(x1)))) → a1(c2(a0(b2(x1)))) (154)

1.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the naturals
[c0(x1)] =
2
· x1 +
1
[c1(x1)] =
2
· x1 +
1
[c2(x1)] =
2
· x1 +
1
[b0(x1)] =
2
· x1 +
1
[b1(x1)] =
2
· x1 +
0
[b2(x1)] =
2
· x1 +
0
[a0(x1)] =
2
· x1 +
1
[a1(x1)] =
2
· x1 +
1
[a2(x1)] =
2
· x1 +
1
all of the following rules can be deleted.
c2(a0(a2(a2(x1)))) → a2(a2(b2(a1(x1)))) (92)
c0(a0(a2(a2(x1)))) → a0(a2(b2(a1(x1)))) (93)
c1(a0(a2(a2(x1)))) → a1(a2(b2(a1(x1)))) (94)
c2(a0(a2(c2(x1)))) → a2(a2(b2(c1(x1)))) (95)
c0(a0(a2(c2(x1)))) → a0(a2(b2(c1(x1)))) (96)
c1(a0(a2(c2(x1)))) → a1(a2(b2(c1(x1)))) (97)
c2(a0(a2(b2(x1)))) → a2(a2(b2(b1(x1)))) (98)
c0(a0(a2(b2(x1)))) → a0(a2(b2(b1(x1)))) (99)
c1(a0(a2(b2(x1)))) → a1(a2(b2(b1(x1)))) (100)
a2(a2(c2(b0(x1)))) → a2(c2(b0(b1(x1)))) (116)
a0(a2(c2(b0(x1)))) → a0(c2(b0(b1(x1)))) (117)
a1(a2(c2(b0(x1)))) → a1(c2(b0(b1(x1)))) (118)
c2(b0(a1(a2(x1)))) → b2(c1(a0(a2(x1)))) (119)
c1(b0(a1(a2(x1)))) → b1(c1(a0(a2(x1)))) (121)
c2(b0(a1(c2(x1)))) → b2(c1(a0(c2(x1)))) (122)
c1(b0(a1(c2(x1)))) → b1(c1(a0(c2(x1)))) (124)
c2(b0(a1(b2(x1)))) → b2(c1(a0(b2(x1)))) (125)
c1(b0(a1(b2(x1)))) → b1(c1(a0(b2(x1)))) (127)
b2(b1(a1(a2(x1)))) → c2(a0(b2(a1(x1)))) (128)
b0(b1(a1(a2(x1)))) → c0(a0(b2(a1(x1)))) (129)
b1(b1(a1(a2(x1)))) → c1(a0(b2(a1(x1)))) (130)
b2(b1(a1(c2(x1)))) → c2(a0(b2(c1(x1)))) (131)
b0(b1(a1(c2(x1)))) → c0(a0(b2(c1(x1)))) (132)
b1(b1(a1(c2(x1)))) → c1(a0(b2(c1(x1)))) (133)
b2(b1(a1(b2(x1)))) → c2(a0(b2(b1(x1)))) (134)
b0(b1(a1(b2(x1)))) → c0(a0(b2(b1(x1)))) (135)
b1(b1(a1(b2(x1)))) → c1(a0(b2(b1(x1)))) (136)

1.1.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c0(x1)] = x1 +
6
[c1(x1)] = x1 +
3
[c2(x1)] = x1 +
1
[b0(x1)] = x1 +
1
[b1(x1)] = x1 +
6
[b2(x1)] = x1 +
0
[a0(x1)] = x1 +
3
[a1(x1)] = x1 +
1
[a2(x1)] = x1 +
0
all of the following rules can be deleted.
a2(c2(b0(a1(x1)))) → a2(a2(a2(a2(x1)))) (101)
a0(c2(b0(a1(x1)))) → a0(a2(a2(a2(x1)))) (102)
a1(c2(b0(a1(x1)))) → a1(a2(a2(a2(x1)))) (103)
a2(c2(b0(c1(x1)))) → a2(a2(a2(c2(x1)))) (104)
a0(c2(b0(c1(x1)))) → a0(a2(a2(c2(x1)))) (105)
a1(c2(b0(c1(x1)))) → a1(a2(a2(c2(x1)))) (106)
a2(c2(b0(b1(x1)))) → a2(a2(a2(b2(x1)))) (107)
a0(c2(b0(b1(x1)))) → a0(a2(a2(b2(x1)))) (108)
a1(c2(b0(b1(x1)))) → a1(a2(a2(b2(x1)))) (109)
a2(a2(c2(a0(x1)))) → a2(c2(b0(a1(x1)))) (110)
a0(a2(c2(a0(x1)))) → a0(c2(b0(a1(x1)))) (111)
a1(a2(c2(a0(x1)))) → a1(c2(b0(a1(x1)))) (112)
a2(a2(c2(c0(x1)))) → a2(c2(b0(c1(x1)))) (113)
a0(a2(c2(c0(x1)))) → a0(c2(b0(c1(x1)))) (114)
a1(a2(c2(c0(x1)))) → a1(c2(b0(c1(x1)))) (115)
c0(b0(a1(a2(x1)))) → b0(c1(a0(a2(x1)))) (120)
c0(b0(a1(c2(x1)))) → b0(c1(a0(c2(x1)))) (123)
c0(b0(a1(b2(x1)))) → b0(c1(a0(b2(x1)))) (126)
a2(c2(c0(a0(x1)))) → c2(a0(c2(a0(x1)))) (137)
a1(c2(c0(a0(x1)))) → c1(a0(c2(a0(x1)))) (139)
a2(c2(c0(c0(x1)))) → c2(a0(c2(c0(x1)))) (140)
a1(c2(c0(c0(x1)))) → c1(a0(c2(c0(x1)))) (142)
a2(c2(c0(b0(x1)))) → c2(a0(c2(b0(x1)))) (143)
a1(c2(c0(b0(x1)))) → c1(a0(c2(b0(x1)))) (145)
c0(a0(a2(a2(x1)))) → a0(c2(a0(a2(x1)))) (147)
c1(a0(a2(a2(x1)))) → a1(c2(a0(a2(x1)))) (148)
c0(a0(a2(c2(x1)))) → a0(c2(a0(c2(x1)))) (150)
c1(a0(a2(c2(x1)))) → a1(c2(a0(c2(x1)))) (151)
c0(a0(a2(b2(x1)))) → a0(c2(a0(b2(x1)))) (153)
c1(a0(a2(b2(x1)))) → a1(c2(a0(b2(x1)))) (154)

1.1.1.1.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
a0(c0(c2(a0(x1)))) → a0(c2(a0(c0(x1)))) (75)
c0(c0(c2(a0(x1)))) → c0(c2(a0(c0(x1)))) (78)
b0(c0(c2(a0(x1)))) → b0(c2(a0(c0(x1)))) (81)
a2(a2(a0(c2(x1)))) → a2(a0(c2(a2(x1)))) (83)
c2(a2(a0(c2(x1)))) → c2(a0(c2(a2(x1)))) (86)
b2(a2(a0(c2(x1)))) → b2(a0(c2(a2(x1)))) (89)

1.1.1.1.1.1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.

1.2 Split

We split R in the relative problem D/R-D and R-D, where the rules D

c(c(a(x1))) → c(a(c(x1))) (4)
are deleted.

1.2.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), a(☐)}

We obtain the transformed TRS
c(c(c(a(x1)))) → c(c(a(c(x1)))) (23)
a(c(c(a(x1)))) → a(c(a(c(x1)))) (27)
c(a(a(c(x1)))) → c(a(c(a(x1)))) (24)
a(a(a(c(x1)))) → a(a(c(a(x1)))) (28)

1.2.1.1 Semantic Labeling

The following interpretations form a model of the rules.

As carrier we take the set {0,1}. Symbols are labeled by the interpretation of their arguments using the interpretations (modulo 2):

[c(x1)] = 2x1 + 0
[a(x1)] = 2x1 + 1

We obtain the labeled TRS
c0(c0(c1(a0(x1)))) → c0(c1(a0(c0(x1)))) (155)
c0(c0(c1(a1(x1)))) → c0(c1(a0(c1(x1)))) (156)
a0(c0(c1(a0(x1)))) → a0(c1(a0(c0(x1)))) (157)
a0(c0(c1(a1(x1)))) → a0(c1(a0(c1(x1)))) (158)
c1(a1(a0(c0(x1)))) → c1(a0(c1(a0(x1)))) (159)
c1(a1(a0(c1(x1)))) → c1(a0(c1(a1(x1)))) (160)
a1(a1(a0(c0(x1)))) → a1(a0(c1(a0(x1)))) (161)
a1(a1(a0(c1(x1)))) → a1(a0(c1(a1(x1)))) (162)

1.2.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c0(x1)] = x1 +
1
[c1(x1)] = x1 +
0
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
all of the following rules can be deleted.
c0(c0(c1(a1(x1)))) → c0(c1(a0(c1(x1)))) (156)
a0(c0(c1(a1(x1)))) → a0(c1(a0(c1(x1)))) (158)
c1(a1(a0(c0(x1)))) → c1(a0(c1(a0(x1)))) (159)
a1(a1(a0(c0(x1)))) → a1(a0(c1(a0(x1)))) (161)

1.2.1.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
a0(c1(c0(c0(x1)))) → c0(a0(c1(c0(x1)))) (163)
a0(c1(c0(a0(x1)))) → c0(a0(c1(a0(x1)))) (164)
c1(a0(a1(c1(x1)))) → a1(c1(a0(c1(x1)))) (165)
c1(a0(a1(a1(x1)))) → a1(c1(a0(a1(x1)))) (166)

1.2.1.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the naturals
[c0(x1)] =
2
· x1 +
1
[c1(x1)] =
2
· x1 +
0
[a0(x1)] =
1
· x1 +
0
[a1(x1)] =
2
· x1 +
0
all of the following rules can be deleted.
a0(c1(c0(c0(x1)))) → c0(a0(c1(c0(x1)))) (163)
a0(c1(c0(a0(x1)))) → c0(a0(c1(a0(x1)))) (164)

1.2.1.1.1.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
c1(a1(a0(c1(x1)))) → c1(a0(c1(a1(x1)))) (160)
a1(a1(a0(c1(x1)))) → a1(a0(c1(a1(x1)))) (162)

1.2.1.1.1.1.1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.

1.2.2 Closure Under Flat Contexts

Using the flat contexts

{c(☐), a(☐)}

We obtain the transformed TRS
c(a(a(c(x1)))) → c(a(c(a(x1)))) (24)
a(a(a(c(x1)))) → a(a(c(a(x1)))) (28)

1.2.2.1 Semantic Labeling

The following interpretations form a model of the rules.

As carrier we take the set {0,1}. Symbols are labeled by the interpretation of their arguments using the interpretations (modulo 2):

[c(x1)] = 2x1 + 0
[a(x1)] = 2x1 + 1

We obtain the labeled TRS
a1(a1(a0(c1(x1)))) → a1(a0(c1(a1(x1)))) (162)
a1(a1(a0(c0(x1)))) → a1(a0(c1(a0(x1)))) (161)
c1(a1(a0(c1(x1)))) → c1(a0(c1(a1(x1)))) (160)
c1(a1(a0(c0(x1)))) → c1(a0(c1(a0(x1)))) (159)

1.2.2.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c0(x1)] = x1 +
1
[c1(x1)] = x1 +
0
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
all of the following rules can be deleted.
a1(a1(a0(c0(x1)))) → a1(a0(c1(a0(x1)))) (161)
c1(a1(a0(c0(x1)))) → c1(a0(c1(a0(x1)))) (159)

1.2.2.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
c1(a0(a1(a1(x1)))) → a1(c1(a0(a1(x1)))) (166)
c1(a0(a1(c1(x1)))) → a1(c1(a0(c1(x1)))) (165)

1.2.2.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the naturals
[c1(x1)] =
2
· x1 +
1
[a0(x1)] =
2
· x1 +
0
[a1(x1)] =
2
· x1 +
1
all of the following rules can be deleted.
c1(a0(a1(a1(x1)))) → a1(c1(a0(a1(x1)))) (166)
c1(a0(a1(c1(x1)))) → a1(c1(a0(c1(x1)))) (165)

1.2.2.1.1.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS

There are no rules.

1.2.2.1.1.1.1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.