Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-52)

The rewrite relation of the following TRS is considered.

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

1.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(a(c(a(x1)))) → c(b(c(c(x1)))) (8)
c(b(c(a(x1)))) → c(b(a(a(x1)))) (9)
b(a(c(a(x1)))) → b(b(c(c(x1)))) (10)
b(b(c(a(x1)))) → b(b(a(a(x1)))) (11)
a(a(c(a(x1)))) → a(b(c(c(x1)))) (12)
a(b(c(a(x1)))) → a(b(a(a(x1)))) (13)
c(a(c(a(x1)))) → c(a(c(b(x1)))) (14)
c(b(b(c(x1)))) → c(b(c(c(x1)))) (15)
c(c(c(b(x1)))) → c(c(a(b(x1)))) (16)
c(b(a(a(x1)))) → c(a(b(a(x1)))) (17)
c(b(a(c(x1)))) → c(a(b(a(x1)))) (18)
b(a(c(a(x1)))) → b(a(c(b(x1)))) (19)
b(b(b(c(x1)))) → b(b(c(c(x1)))) (20)
b(c(c(b(x1)))) → b(c(a(b(x1)))) (21)
b(b(a(a(x1)))) → b(a(b(a(x1)))) (22)
b(b(a(c(x1)))) → b(a(b(a(x1)))) (23)
a(a(c(a(x1)))) → a(a(c(b(x1)))) (24)
a(b(b(c(x1)))) → a(b(c(c(x1)))) (25)
a(c(c(b(x1)))) → a(c(a(b(x1)))) (26)
a(b(a(a(x1)))) → a(a(b(a(x1)))) (27)
a(b(a(c(x1)))) → a(a(b(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(a0(c2(a2(x1)))) → a1(b0(c0(c2(x1)))) (29)
a2(a0(c2(a0(x1)))) → a1(b0(c0(c0(x1)))) (30)
a2(a0(c2(a1(x1)))) → a1(b0(c0(c1(x1)))) (31)
c2(a0(c2(a2(x1)))) → c1(b0(c0(c2(x1)))) (32)
c2(a0(c2(a0(x1)))) → c1(b0(c0(c0(x1)))) (33)
c2(a0(c2(a1(x1)))) → c1(b0(c0(c1(x1)))) (34)
b2(a0(c2(a2(x1)))) → b1(b0(c0(c2(x1)))) (35)
b2(a0(c2(a0(x1)))) → b1(b0(c0(c0(x1)))) (36)
b2(a0(c2(a1(x1)))) → b1(b0(c0(c1(x1)))) (37)
a1(b0(c2(a2(x1)))) → a1(b2(a2(a2(x1)))) (38)
a1(b0(c2(a0(x1)))) → a1(b2(a2(a0(x1)))) (39)
a1(b0(c2(a1(x1)))) → a1(b2(a2(a1(x1)))) (40)
c1(b0(c2(a2(x1)))) → c1(b2(a2(a2(x1)))) (41)
c1(b0(c2(a0(x1)))) → c1(b2(a2(a0(x1)))) (42)
c1(b0(c2(a1(x1)))) → c1(b2(a2(a1(x1)))) (43)
b1(b0(c2(a2(x1)))) → b1(b2(a2(a2(x1)))) (44)
b1(b0(c2(a0(x1)))) → b1(b2(a2(a0(x1)))) (45)
b1(b0(c2(a1(x1)))) → b1(b2(a2(a1(x1)))) (46)
a2(a0(c2(a2(x1)))) → a2(a0(c1(b2(x1)))) (47)
a2(a0(c2(a0(x1)))) → a2(a0(c1(b0(x1)))) (48)
a2(a0(c2(a1(x1)))) → a2(a0(c1(b1(x1)))) (49)
c2(a0(c2(a2(x1)))) → c2(a0(c1(b2(x1)))) (50)
c2(a0(c2(a0(x1)))) → c2(a0(c1(b0(x1)))) (51)
c2(a0(c2(a1(x1)))) → c2(a0(c1(b1(x1)))) (52)
b2(a0(c2(a2(x1)))) → b2(a0(c1(b2(x1)))) (53)
b2(a0(c2(a0(x1)))) → b2(a0(c1(b0(x1)))) (54)
b2(a0(c2(a1(x1)))) → b2(a0(c1(b1(x1)))) (55)
a1(b1(b0(c2(x1)))) → a1(b0(c0(c2(x1)))) (56)
a1(b1(b0(c0(x1)))) → a1(b0(c0(c0(x1)))) (57)
a1(b1(b0(c1(x1)))) → a1(b0(c0(c1(x1)))) (58)
c1(b1(b0(c2(x1)))) → c1(b0(c0(c2(x1)))) (59)
c1(b1(b0(c0(x1)))) → c1(b0(c0(c0(x1)))) (60)
c1(b1(b0(c1(x1)))) → c1(b0(c0(c1(x1)))) (61)
b1(b1(b0(c2(x1)))) → b1(b0(c0(c2(x1)))) (62)
b1(b1(b0(c0(x1)))) → b1(b0(c0(c0(x1)))) (63)
b1(b1(b0(c1(x1)))) → b1(b0(c0(c1(x1)))) (64)
a0(c0(c1(b2(x1)))) → a0(c2(a1(b2(x1)))) (65)
a0(c0(c1(b0(x1)))) → a0(c2(a1(b0(x1)))) (66)
a0(c0(c1(b1(x1)))) → a0(c2(a1(b1(x1)))) (67)
c0(c0(c1(b2(x1)))) → c0(c2(a1(b2(x1)))) (68)
c0(c0(c1(b0(x1)))) → c0(c2(a1(b0(x1)))) (69)
c0(c0(c1(b1(x1)))) → c0(c2(a1(b1(x1)))) (70)
b0(c0(c1(b2(x1)))) → b0(c2(a1(b2(x1)))) (71)
b0(c0(c1(b0(x1)))) → b0(c2(a1(b0(x1)))) (72)
b0(c0(c1(b1(x1)))) → b0(c2(a1(b1(x1)))) (73)
a1(b2(a2(a2(x1)))) → a2(a1(b2(a2(x1)))) (74)
a1(b2(a2(a0(x1)))) → a2(a1(b2(a0(x1)))) (75)
a1(b2(a2(a1(x1)))) → a2(a1(b2(a1(x1)))) (76)
c1(b2(a2(a2(x1)))) → c2(a1(b2(a2(x1)))) (77)
c1(b2(a2(a0(x1)))) → c2(a1(b2(a0(x1)))) (78)
c1(b2(a2(a1(x1)))) → c2(a1(b2(a1(x1)))) (79)
b1(b2(a2(a2(x1)))) → b2(a1(b2(a2(x1)))) (80)
b1(b2(a2(a0(x1)))) → b2(a1(b2(a0(x1)))) (81)
b1(b2(a2(a1(x1)))) → b2(a1(b2(a1(x1)))) (82)
a1(b2(a0(c2(x1)))) → a2(a1(b2(a2(x1)))) (83)
a1(b2(a0(c0(x1)))) → a2(a1(b2(a0(x1)))) (84)
a1(b2(a0(c1(x1)))) → a2(a1(b2(a1(x1)))) (85)
c1(b2(a0(c2(x1)))) → c2(a1(b2(a2(x1)))) (86)
c1(b2(a0(c0(x1)))) → c2(a1(b2(a0(x1)))) (87)
c1(b2(a0(c1(x1)))) → c2(a1(b2(a1(x1)))) (88)
b1(b2(a0(c2(x1)))) → b2(a1(b2(a2(x1)))) (89)
b1(b2(a0(c0(x1)))) → b2(a1(b2(a0(x1)))) (90)
b1(b2(a0(c1(x1)))) → b2(a1(b2(a1(x1)))) (91)

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 +
1
[c1(x1)] = x1 +
0
[c2(x1)] = x1 +
1
[b0(x1)] = x1 +
1
[b1(x1)] = x1 +
1
[b2(x1)] = x1 +
0
[a0(x1)] = x1 +
4
[a1(x1)] = x1 +
0
[a2(x1)] = x1 +
1
all of the following rules can be deleted.
a2(a0(c2(a2(x1)))) → a1(b0(c0(c2(x1)))) (29)
a2(a0(c2(a0(x1)))) → a1(b0(c0(c0(x1)))) (30)
a2(a0(c2(a1(x1)))) → a1(b0(c0(c1(x1)))) (31)
c2(a0(c2(a2(x1)))) → c1(b0(c0(c2(x1)))) (32)
c2(a0(c2(a0(x1)))) → c1(b0(c0(c0(x1)))) (33)
c2(a0(c2(a1(x1)))) → c1(b0(c0(c1(x1)))) (34)
b2(a0(c2(a2(x1)))) → b1(b0(c0(c2(x1)))) (35)
b2(a0(c2(a0(x1)))) → b1(b0(c0(c0(x1)))) (36)
b2(a0(c2(a1(x1)))) → b1(b0(c0(c1(x1)))) (37)
a1(b0(c2(a2(x1)))) → a1(b2(a2(a2(x1)))) (38)
a1(b0(c2(a0(x1)))) → a1(b2(a2(a0(x1)))) (39)
a1(b0(c2(a1(x1)))) → a1(b2(a2(a1(x1)))) (40)
c1(b0(c2(a2(x1)))) → c1(b2(a2(a2(x1)))) (41)
c1(b0(c2(a0(x1)))) → c1(b2(a2(a0(x1)))) (42)
c1(b0(c2(a1(x1)))) → c1(b2(a2(a1(x1)))) (43)
b1(b0(c2(a2(x1)))) → b1(b2(a2(a2(x1)))) (44)
b1(b0(c2(a0(x1)))) → b1(b2(a2(a0(x1)))) (45)
b1(b0(c2(a1(x1)))) → b1(b2(a2(a1(x1)))) (46)
a2(a0(c2(a2(x1)))) → a2(a0(c1(b2(x1)))) (47)
a2(a0(c2(a0(x1)))) → a2(a0(c1(b0(x1)))) (48)
c2(a0(c2(a2(x1)))) → c2(a0(c1(b2(x1)))) (50)
c2(a0(c2(a0(x1)))) → c2(a0(c1(b0(x1)))) (51)
b2(a0(c2(a2(x1)))) → b2(a0(c1(b2(x1)))) (53)
b2(a0(c2(a0(x1)))) → b2(a0(c1(b0(x1)))) (54)
b1(b2(a2(a2(x1)))) → b2(a1(b2(a2(x1)))) (80)
b1(b2(a2(a0(x1)))) → b2(a1(b2(a0(x1)))) (81)
b1(b2(a2(a1(x1)))) → b2(a1(b2(a1(x1)))) (82)
a1(b2(a0(c2(x1)))) → a2(a1(b2(a2(x1)))) (83)
a1(b2(a0(c1(x1)))) → a2(a1(b2(a1(x1)))) (85)
c1(b2(a0(c2(x1)))) → c2(a1(b2(a2(x1)))) (86)
c1(b2(a0(c1(x1)))) → c2(a1(b2(a1(x1)))) (88)
b1(b2(a0(c2(x1)))) → b2(a1(b2(a2(x1)))) (89)
b1(b2(a0(c0(x1)))) → b2(a1(b2(a0(x1)))) (90)
b1(b2(a0(c1(x1)))) → b2(a1(b2(a1(x1)))) (91)

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

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

1.2.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

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

1.2.1.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(c(a(c(a(x1))))) → c(c(a(c(b(x1))))) (92)
c(c(b(b(c(x1))))) → c(c(b(c(c(x1))))) (93)
c(c(c(c(b(x1))))) → c(c(c(a(b(x1))))) (94)
c(c(b(a(c(x1))))) → c(c(a(b(a(x1))))) (95)
c(b(a(c(a(x1))))) → c(b(a(c(b(x1))))) (96)
c(b(b(b(c(x1))))) → c(b(b(c(c(x1))))) (97)
c(b(c(c(b(x1))))) → c(b(c(a(b(x1))))) (98)
c(b(b(a(c(x1))))) → c(b(a(b(a(x1))))) (99)
c(a(a(c(a(x1))))) → c(a(a(c(b(x1))))) (100)
c(a(b(b(c(x1))))) → c(a(b(c(c(x1))))) (101)
c(a(c(c(b(x1))))) → c(a(c(a(b(x1))))) (102)
c(a(b(a(c(x1))))) → c(a(a(b(a(x1))))) (103)
b(c(a(c(a(x1))))) → b(c(a(c(b(x1))))) (104)
b(c(b(b(c(x1))))) → b(c(b(c(c(x1))))) (105)
b(c(c(c(b(x1))))) → b(c(c(a(b(x1))))) (106)
b(c(b(a(c(x1))))) → b(c(a(b(a(x1))))) (107)
b(b(a(c(a(x1))))) → b(b(a(c(b(x1))))) (108)
b(b(b(b(c(x1))))) → b(b(b(c(c(x1))))) (109)
b(b(c(c(b(x1))))) → b(b(c(a(b(x1))))) (110)
b(b(b(a(c(x1))))) → b(b(a(b(a(x1))))) (111)
b(a(a(c(a(x1))))) → b(a(a(c(b(x1))))) (112)
b(a(b(b(c(x1))))) → b(a(b(c(c(x1))))) (113)
b(a(c(c(b(x1))))) → b(a(c(a(b(x1))))) (114)
b(a(b(a(c(x1))))) → b(a(a(b(a(x1))))) (115)
a(c(a(c(a(x1))))) → a(c(a(c(b(x1))))) (116)
a(c(b(b(c(x1))))) → a(c(b(c(c(x1))))) (117)
a(c(c(c(b(x1))))) → a(c(c(a(b(x1))))) (118)
a(c(b(a(c(x1))))) → a(c(a(b(a(x1))))) (119)
a(b(a(c(a(x1))))) → a(b(a(c(b(x1))))) (120)
a(b(b(b(c(x1))))) → a(b(b(c(c(x1))))) (121)
a(b(c(c(b(x1))))) → a(b(c(a(b(x1))))) (122)
a(b(b(a(c(x1))))) → a(b(a(b(a(x1))))) (123)
a(a(a(c(a(x1))))) → a(a(a(c(b(x1))))) (124)
a(a(b(b(c(x1))))) → a(a(b(c(c(x1))))) (125)
a(a(c(c(b(x1))))) → a(a(c(a(b(x1))))) (126)
a(a(b(a(c(x1))))) → a(a(a(b(a(x1))))) (127)
c(c(b(a(a(x1))))) → c(c(a(b(a(x1))))) (128)
c(b(b(a(a(x1))))) → c(b(a(b(a(x1))))) (129)
c(a(b(a(a(x1))))) → c(a(a(b(a(x1))))) (130)
b(c(b(a(a(x1))))) → b(c(a(b(a(x1))))) (131)
b(b(b(a(a(x1))))) → b(b(a(b(a(x1))))) (132)
b(a(b(a(a(x1))))) → b(a(a(b(a(x1))))) (133)
a(c(b(a(a(x1))))) → a(c(a(b(a(x1))))) (134)
a(b(b(a(a(x1))))) → a(b(a(b(a(x1))))) (135)
a(a(b(a(a(x1))))) → a(a(a(b(a(x1))))) (136)

1.2.1.1.1 Semantic Labeling

The following interpretations form a model of the rules.

As carrier we take the set {0,...,8}. Symbols are labeled by the interpretation of their arguments using the interpretations (modulo 9):

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

We obtain the labeled TRS

There are 405 ruless (increase limit for explicit display).

1.2.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c0(x1)] = x1 +
4
[c3(x1)] = x1 +
18
[c6(x1)] = x1 +
0
[c1(x1)] = x1 +
0
[c4(x1)] = x1 +
3
[c7(x1)] = x1 +
4
[c2(x1)] = x1 +
25
[c5(x1)] = x1 +
4
[c8(x1)] = x1 +
4
[b0(x1)] = x1 +
0
[b3(x1)] = x1 +
25
[b6(x1)] = x1 +
8
[b1(x1)] = x1 +
2
[b4(x1)] = x1 +
5
[b7(x1)] = x1 +
0
[b2(x1)] = x1 +
18
[b5(x1)] = x1 +
0
[b8(x1)] = x1 +
3
[a0(x1)] = x1 +
25
[a3(x1)] = x1 +
0
[a6(x1)] = x1 +
1
[a1(x1)] = x1 +
5
[a4(x1)] = x1 +
8
[a7(x1)] = x1 +
1
[a2(x1)] = x1 +
25
[a5(x1)] = x1 +
0
[a8(x1)] = x1 +
3
all of the following rules can be deleted.

There are 393 ruless (increase limit for explicit display).

1.2.1.1.1.1.1 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

{b(☐), a(☐)}

We obtain the transformed TRS
b(b(a(a(x1)))) → b(a(b(a(x1)))) (22)
a(b(a(a(x1)))) → a(a(b(a(x1)))) (27)

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):

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

We obtain the labeled TRS
b0(b1(a1(a0(x1)))) → b1(a0(b1(a0(x1)))) (542)
b0(b1(a1(a1(x1)))) → b1(a0(b1(a1(x1)))) (543)
a0(b1(a1(a0(x1)))) → a1(a0(b1(a0(x1)))) (544)
a0(b1(a1(a1(x1)))) → a1(a0(b1(a1(x1)))) (545)

1.2.2.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[b0(x1)] = x1 +
1
[b1(x1)] = x1 +
0
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
all of the following rules can be deleted.
b0(b1(a1(a0(x1)))) → b1(a0(b1(a0(x1)))) (542)
b0(b1(a1(a1(x1)))) → b1(a0(b1(a1(x1)))) (543)

1.2.2.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the naturals
[b1(x1)] =
2
· x1 +
1
[a0(x1)] =
2
· x1 +
0
[a1(x1)] =
2
· x1 +
1
all of the following rules can be deleted.
a0(b1(a1(a0(x1)))) → a1(a0(b1(a0(x1)))) (544)
a0(b1(a1(a1(x1)))) → a1(a0(b1(a1(x1)))) (545)

1.2.2.1.1.1.1 R is empty

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