Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-142)

The rewrite relation of the following TRS is considered.

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

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

1.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(b(c(b(x1)))) → c(b(a(c(x1)))) (8)
c(b(b(c(x1)))) → c(c(a(b(x1)))) (9)
c(b(b(b(x1)))) → c(a(b(b(x1)))) (10)
c(b(b(c(x1)))) → c(b(c(c(x1)))) (11)
b(b(c(b(x1)))) → b(b(a(c(x1)))) (12)
b(b(b(c(x1)))) → b(c(a(b(x1)))) (13)
b(b(b(b(x1)))) → b(a(b(b(x1)))) (14)
b(b(b(c(x1)))) → b(b(c(c(x1)))) (15)
a(b(c(b(x1)))) → a(b(a(c(x1)))) (16)
a(b(b(c(x1)))) → a(c(a(b(x1)))) (17)
a(b(b(b(x1)))) → a(a(b(b(x1)))) (18)
a(b(b(c(x1)))) → a(b(c(c(x1)))) (19)
c(a(a(b(x1)))) → c(a(c(b(x1)))) (20)
c(c(c(c(x1)))) → c(a(b(a(x1)))) (21)
c(b(a(a(x1)))) → c(a(c(c(x1)))) (22)
b(a(a(b(x1)))) → b(a(c(b(x1)))) (23)
b(c(c(c(x1)))) → b(a(b(a(x1)))) (24)
b(b(a(a(x1)))) → b(a(c(c(x1)))) (25)
a(a(a(b(x1)))) → a(a(c(b(x1)))) (26)
a(c(c(c(x1)))) → a(a(b(a(x1)))) (27)
a(b(a(a(x1)))) → a(a(c(c(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
a1(b0(c1(b2(x1)))) → a1(b2(a0(c2(x1)))) (29)
a1(b0(c1(b1(x1)))) → a1(b2(a0(c1(x1)))) (30)
a1(b0(c1(b0(x1)))) → a1(b2(a0(c0(x1)))) (31)
b1(b0(c1(b2(x1)))) → b1(b2(a0(c2(x1)))) (32)
b1(b0(c1(b1(x1)))) → b1(b2(a0(c1(x1)))) (33)
b1(b0(c1(b0(x1)))) → b1(b2(a0(c0(x1)))) (34)
c1(b0(c1(b2(x1)))) → c1(b2(a0(c2(x1)))) (35)
c1(b0(c1(b1(x1)))) → c1(b2(a0(c1(x1)))) (36)
c1(b0(c1(b0(x1)))) → c1(b2(a0(c0(x1)))) (37)
a1(b1(b0(c2(x1)))) → a0(c2(a1(b2(x1)))) (38)
a1(b1(b0(c1(x1)))) → a0(c2(a1(b1(x1)))) (39)
a1(b1(b0(c0(x1)))) → a0(c2(a1(b0(x1)))) (40)
b1(b1(b0(c2(x1)))) → b0(c2(a1(b2(x1)))) (41)
b1(b1(b0(c1(x1)))) → b0(c2(a1(b1(x1)))) (42)
b1(b1(b0(c0(x1)))) → b0(c2(a1(b0(x1)))) (43)
c1(b1(b0(c2(x1)))) → c0(c2(a1(b2(x1)))) (44)
c1(b1(b0(c1(x1)))) → c0(c2(a1(b1(x1)))) (45)
c1(b1(b0(c0(x1)))) → c0(c2(a1(b0(x1)))) (46)
a1(b1(b1(b2(x1)))) → a2(a1(b1(b2(x1)))) (47)
a1(b1(b1(b1(x1)))) → a2(a1(b1(b1(x1)))) (48)
a1(b1(b1(b0(x1)))) → a2(a1(b1(b0(x1)))) (49)
b1(b1(b1(b2(x1)))) → b2(a1(b1(b2(x1)))) (50)
b1(b1(b1(b1(x1)))) → b2(a1(b1(b1(x1)))) (51)
b1(b1(b1(b0(x1)))) → b2(a1(b1(b0(x1)))) (52)
c1(b1(b1(b2(x1)))) → c2(a1(b1(b2(x1)))) (53)
c1(b1(b1(b1(x1)))) → c2(a1(b1(b1(x1)))) (54)
c1(b1(b1(b0(x1)))) → c2(a1(b1(b0(x1)))) (55)
a1(b1(b0(c2(x1)))) → a1(b0(c0(c2(x1)))) (56)
a1(b1(b0(c1(x1)))) → a1(b0(c0(c1(x1)))) (57)
a1(b1(b0(c0(x1)))) → a1(b0(c0(c0(x1)))) (58)
b1(b1(b0(c2(x1)))) → b1(b0(c0(c2(x1)))) (59)
b1(b1(b0(c1(x1)))) → b1(b0(c0(c1(x1)))) (60)
b1(b1(b0(c0(x1)))) → b1(b0(c0(c0(x1)))) (61)
c1(b1(b0(c2(x1)))) → c1(b0(c0(c2(x1)))) (62)
c1(b1(b0(c1(x1)))) → c1(b0(c0(c1(x1)))) (63)
c1(b1(b0(c0(x1)))) → c1(b0(c0(c0(x1)))) (64)
a2(a2(a1(b2(x1)))) → a2(a0(c1(b2(x1)))) (65)
a2(a2(a1(b1(x1)))) → a2(a0(c1(b1(x1)))) (66)
a2(a2(a1(b0(x1)))) → a2(a0(c1(b0(x1)))) (67)
b2(a2(a1(b2(x1)))) → b2(a0(c1(b2(x1)))) (68)
b2(a2(a1(b1(x1)))) → b2(a0(c1(b1(x1)))) (69)
b2(a2(a1(b0(x1)))) → b2(a0(c1(b0(x1)))) (70)
c2(a2(a1(b2(x1)))) → c2(a0(c1(b2(x1)))) (71)
c2(a2(a1(b1(x1)))) → c2(a0(c1(b1(x1)))) (72)
c2(a2(a1(b0(x1)))) → c2(a0(c1(b0(x1)))) (73)
a0(c0(c0(c2(x1)))) → a2(a1(b2(a2(x1)))) (74)
a0(c0(c0(c1(x1)))) → a2(a1(b2(a1(x1)))) (75)
a0(c0(c0(c0(x1)))) → a2(a1(b2(a0(x1)))) (76)
b0(c0(c0(c2(x1)))) → b2(a1(b2(a2(x1)))) (77)
b0(c0(c0(c1(x1)))) → b2(a1(b2(a1(x1)))) (78)
b0(c0(c0(c0(x1)))) → b2(a1(b2(a0(x1)))) (79)
c0(c0(c0(c2(x1)))) → c2(a1(b2(a2(x1)))) (80)
c0(c0(c0(c1(x1)))) → c2(a1(b2(a1(x1)))) (81)
c0(c0(c0(c0(x1)))) → c2(a1(b2(a0(x1)))) (82)
a1(b2(a2(a2(x1)))) → a2(a0(c0(c2(x1)))) (83)
a1(b2(a2(a1(x1)))) → a2(a0(c0(c1(x1)))) (84)
a1(b2(a2(a0(x1)))) → a2(a0(c0(c0(x1)))) (85)
b1(b2(a2(a2(x1)))) → b2(a0(c0(c2(x1)))) (86)
b1(b2(a2(a1(x1)))) → b2(a0(c0(c1(x1)))) (87)
b1(b2(a2(a0(x1)))) → b2(a0(c0(c0(x1)))) (88)
c1(b2(a2(a2(x1)))) → c2(a0(c0(c2(x1)))) (89)
c1(b2(a2(a1(x1)))) → c2(a0(c0(c1(x1)))) (90)
c1(b2(a2(a0(x1)))) → c2(a0(c0(c0(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 +
1
[c2(x1)] = x1 +
0
[b0(x1)] = x1 +
2
[b1(x1)] = x1 +
3
[b2(x1)] = x1 +
1
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
[a2(x1)] = x1 +
0
all of the following rules can be deleted.
a1(b0(c1(b2(x1)))) → a1(b2(a0(c2(x1)))) (29)
a1(b0(c1(b1(x1)))) → a1(b2(a0(c1(x1)))) (30)
a1(b0(c1(b0(x1)))) → a1(b2(a0(c0(x1)))) (31)
b1(b0(c1(b2(x1)))) → b1(b2(a0(c2(x1)))) (32)
b1(b0(c1(b1(x1)))) → b1(b2(a0(c1(x1)))) (33)
b1(b0(c1(b0(x1)))) → b1(b2(a0(c0(x1)))) (34)
c1(b0(c1(b2(x1)))) → c1(b2(a0(c2(x1)))) (35)
c1(b0(c1(b1(x1)))) → c1(b2(a0(c1(x1)))) (36)
c1(b0(c1(b0(x1)))) → c1(b2(a0(c0(x1)))) (37)
a1(b1(b0(c2(x1)))) → a0(c2(a1(b2(x1)))) (38)
a1(b1(b0(c1(x1)))) → a0(c2(a1(b1(x1)))) (39)
a1(b1(b0(c0(x1)))) → a0(c2(a1(b0(x1)))) (40)
b1(b1(b0(c2(x1)))) → b0(c2(a1(b2(x1)))) (41)
b1(b1(b0(c1(x1)))) → b0(c2(a1(b1(x1)))) (42)
b1(b1(b0(c0(x1)))) → b0(c2(a1(b0(x1)))) (43)
c1(b1(b0(c2(x1)))) → c0(c2(a1(b2(x1)))) (44)
c1(b1(b0(c1(x1)))) → c0(c2(a1(b1(x1)))) (45)
c1(b1(b0(c0(x1)))) → c0(c2(a1(b0(x1)))) (46)
a1(b1(b1(b2(x1)))) → a2(a1(b1(b2(x1)))) (47)
a1(b1(b1(b1(x1)))) → a2(a1(b1(b1(x1)))) (48)
a1(b1(b1(b0(x1)))) → a2(a1(b1(b0(x1)))) (49)
b1(b1(b1(b2(x1)))) → b2(a1(b1(b2(x1)))) (50)
b1(b1(b1(b1(x1)))) → b2(a1(b1(b1(x1)))) (51)
b1(b1(b1(b0(x1)))) → b2(a1(b1(b0(x1)))) (52)
c1(b1(b1(b2(x1)))) → c2(a1(b1(b2(x1)))) (53)
c1(b1(b1(b1(x1)))) → c2(a1(b1(b1(x1)))) (54)
c1(b1(b1(b0(x1)))) → c2(a1(b1(b0(x1)))) (55)
a1(b1(b0(c2(x1)))) → a1(b0(c0(c2(x1)))) (56)
a1(b1(b0(c1(x1)))) → a1(b0(c0(c1(x1)))) (57)
a1(b1(b0(c0(x1)))) → a1(b0(c0(c0(x1)))) (58)
b1(b1(b0(c2(x1)))) → b1(b0(c0(c2(x1)))) (59)
b1(b1(b0(c1(x1)))) → b1(b0(c0(c1(x1)))) (60)
b1(b1(b0(c0(x1)))) → b1(b0(c0(c0(x1)))) (61)
c1(b1(b0(c2(x1)))) → c1(b0(c0(c2(x1)))) (62)
c1(b1(b0(c1(x1)))) → c1(b0(c0(c1(x1)))) (63)
c1(b1(b0(c0(x1)))) → c1(b0(c0(c0(x1)))) (64)
a0(c0(c0(c0(x1)))) → a2(a1(b2(a0(x1)))) (76)
b0(c0(c0(c2(x1)))) → b2(a1(b2(a2(x1)))) (77)
b0(c0(c0(c1(x1)))) → b2(a1(b2(a1(x1)))) (78)
b0(c0(c0(c0(x1)))) → b2(a1(b2(a0(x1)))) (79)
c0(c0(c0(c2(x1)))) → c2(a1(b2(a2(x1)))) (80)
c0(c0(c0(c1(x1)))) → c2(a1(b2(a1(x1)))) (81)
c0(c0(c0(c0(x1)))) → c2(a1(b2(a0(x1)))) (82)
a1(b2(a2(a2(x1)))) → a2(a0(c0(c2(x1)))) (83)
a1(b2(a2(a1(x1)))) → a2(a0(c0(c1(x1)))) (84)
b1(b2(a2(a2(x1)))) → b2(a0(c0(c2(x1)))) (86)
b1(b2(a2(a1(x1)))) → b2(a0(c0(c1(x1)))) (87)
b1(b2(a2(a0(x1)))) → b2(a0(c0(c0(x1)))) (88)
c1(b2(a2(a2(x1)))) → c2(a0(c0(c2(x1)))) (89)
c1(b2(a2(a1(x1)))) → c2(a0(c0(c1(x1)))) (90)

1.1.1.1.1 R is empty

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

1.2 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(a(a(b(x1)))) → c(a(c(b(x1)))) (20)
c(c(c(c(x1)))) → c(a(b(a(x1)))) (21)
c(b(a(a(x1)))) → c(a(c(c(x1)))) (22)
b(a(a(b(x1)))) → b(a(c(b(x1)))) (23)
b(c(c(c(x1)))) → b(a(b(a(x1)))) (24)
b(b(a(a(x1)))) → b(a(c(c(x1)))) (25)
a(a(a(b(x1)))) → a(a(c(b(x1)))) (26)
a(c(c(c(x1)))) → a(a(b(a(x1)))) (27)
a(b(a(a(x1)))) → a(a(c(c(x1)))) (28)

1.2.1 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(a1(b2(x1)))) → a2(a0(c1(b2(x1)))) (65)
a2(a2(a1(b1(x1)))) → a2(a0(c1(b1(x1)))) (66)
a2(a2(a1(b0(x1)))) → a2(a0(c1(b0(x1)))) (67)
b2(a2(a1(b2(x1)))) → b2(a0(c1(b2(x1)))) (68)
b2(a2(a1(b1(x1)))) → b2(a0(c1(b1(x1)))) (69)
b2(a2(a1(b0(x1)))) → b2(a0(c1(b0(x1)))) (70)
c2(a2(a1(b2(x1)))) → c2(a0(c1(b2(x1)))) (71)
c2(a2(a1(b1(x1)))) → c2(a0(c1(b1(x1)))) (72)
c2(a2(a1(b0(x1)))) → c2(a0(c1(b0(x1)))) (73)
a0(c0(c0(c2(x1)))) → a2(a1(b2(a2(x1)))) (74)
a0(c0(c0(c1(x1)))) → a2(a1(b2(a1(x1)))) (75)
a0(c0(c0(c0(x1)))) → a2(a1(b2(a0(x1)))) (76)
b0(c0(c0(c2(x1)))) → b2(a1(b2(a2(x1)))) (77)
b0(c0(c0(c1(x1)))) → b2(a1(b2(a1(x1)))) (78)
b0(c0(c0(c0(x1)))) → b2(a1(b2(a0(x1)))) (79)
c0(c0(c0(c2(x1)))) → c2(a1(b2(a2(x1)))) (80)
c0(c0(c0(c1(x1)))) → c2(a1(b2(a1(x1)))) (81)
c0(c0(c0(c0(x1)))) → c2(a1(b2(a0(x1)))) (82)
a1(b2(a2(a2(x1)))) → a2(a0(c0(c2(x1)))) (83)
a1(b2(a2(a1(x1)))) → a2(a0(c0(c1(x1)))) (84)
a1(b2(a2(a0(x1)))) → a2(a0(c0(c0(x1)))) (85)
b1(b2(a2(a2(x1)))) → b2(a0(c0(c2(x1)))) (86)
b1(b2(a2(a1(x1)))) → b2(a0(c0(c1(x1)))) (87)
b1(b2(a2(a0(x1)))) → b2(a0(c0(c0(x1)))) (88)
c1(b2(a2(a2(x1)))) → c2(a0(c0(c2(x1)))) (89)
c1(b2(a2(a1(x1)))) → c2(a0(c0(c1(x1)))) (90)
c1(b2(a2(a0(x1)))) → c2(a0(c0(c0(x1)))) (91)

1.2.1.1 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 +
1
[c2(x1)] = x1 +
0
[b0(x1)] = x1 +
3
[b1(x1)] = x1 +
3
[b2(x1)] = x1 +
1
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
[a2(x1)] = x1 +
0
all of the following rules can be deleted.
a0(c0(c0(c0(x1)))) → a2(a1(b2(a0(x1)))) (76)
b0(c0(c0(c2(x1)))) → b2(a1(b2(a2(x1)))) (77)
b0(c0(c0(c1(x1)))) → b2(a1(b2(a1(x1)))) (78)
b0(c0(c0(c0(x1)))) → b2(a1(b2(a0(x1)))) (79)
c0(c0(c0(c2(x1)))) → c2(a1(b2(a2(x1)))) (80)
c0(c0(c0(c1(x1)))) → c2(a1(b2(a1(x1)))) (81)
c0(c0(c0(c0(x1)))) → c2(a1(b2(a0(x1)))) (82)
a1(b2(a2(a2(x1)))) → a2(a0(c0(c2(x1)))) (83)
a1(b2(a2(a1(x1)))) → a2(a0(c0(c1(x1)))) (84)
b1(b2(a2(a2(x1)))) → b2(a0(c0(c2(x1)))) (86)
b1(b2(a2(a1(x1)))) → b2(a0(c0(c1(x1)))) (87)
b1(b2(a2(a0(x1)))) → b2(a0(c0(c0(x1)))) (88)
c1(b2(a2(a2(x1)))) → c2(a0(c0(c2(x1)))) (89)
c1(b2(a2(a1(x1)))) → c2(a0(c0(c1(x1)))) (90)

1.2.1.1.1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
b2(a1(a2(a2(x1)))) → b2(c1(a0(a2(x1)))) (92)
b1(a1(a2(a2(x1)))) → b1(c1(a0(a2(x1)))) (93)
b0(a1(a2(a2(x1)))) → b0(c1(a0(a2(x1)))) (94)
b2(a1(a2(b2(x1)))) → b2(c1(a0(b2(x1)))) (95)
b1(a1(a2(b2(x1)))) → b1(c1(a0(b2(x1)))) (96)
b0(a1(a2(b2(x1)))) → b0(c1(a0(b2(x1)))) (97)
b2(a1(a2(c2(x1)))) → b2(c1(a0(c2(x1)))) (98)
b1(a1(a2(c2(x1)))) → b1(c1(a0(c2(x1)))) (99)
b0(a1(a2(c2(x1)))) → b0(c1(a0(c2(x1)))) (100)
c2(c0(c0(a0(x1)))) → a2(b2(a1(a2(x1)))) (101)
c1(c0(c0(a0(x1)))) → a1(b2(a1(a2(x1)))) (102)
a0(a2(b2(a1(x1)))) → c0(c0(a0(a2(x1)))) (103)
a0(a2(b2(c1(x1)))) → c0(c0(a0(c2(x1)))) (104)

1.2.1.1.1.1 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 +
0
[b0(x1)] =
1
· x1 +
1
[b1(x1)] =
1
· x1 +
1
[b2(x1)] =
2
· x1 +
0
[a0(x1)] =
2
· x1 +
0
[a1(x1)] =
2
· x1 +
1
[a2(x1)] =
2
· x1 +
0
all of the following rules can be deleted.
c2(c0(c0(a0(x1)))) → a2(b2(a1(a2(x1)))) (101)
c1(c0(c0(a0(x1)))) → a1(b2(a1(a2(x1)))) (102)
a0(a2(b2(a1(x1)))) → c0(c0(a0(a2(x1)))) (103)
a0(a2(b2(c1(x1)))) → c0(c0(a0(c2(x1)))) (104)

1.2.1.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c1(x1)] = x1 +
0
[c2(x1)] = x1 +
0
[b0(x1)] = x1 +
0
[b1(x1)] = x1 +
0
[b2(x1)] = x1 +
0
[a0(x1)] = x1 +
0
[a1(x1)] = x1 +
1
[a2(x1)] = x1 +
1
all of the following rules can be deleted.
b2(a1(a2(a2(x1)))) → b2(c1(a0(a2(x1)))) (92)
b1(a1(a2(a2(x1)))) → b1(c1(a0(a2(x1)))) (93)
b0(a1(a2(a2(x1)))) → b0(c1(a0(a2(x1)))) (94)
b2(a1(a2(b2(x1)))) → b2(c1(a0(b2(x1)))) (95)
b1(a1(a2(b2(x1)))) → b1(c1(a0(b2(x1)))) (96)
b0(a1(a2(b2(x1)))) → b0(c1(a0(b2(x1)))) (97)
b2(a1(a2(c2(x1)))) → b2(c1(a0(c2(x1)))) (98)
b1(a1(a2(c2(x1)))) → b1(c1(a0(c2(x1)))) (99)
b0(a1(a2(c2(x1)))) → b0(c1(a0(c2(x1)))) (100)

1.2.1.1.1.1.1.1 String Reversal

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

There are no rules.

1.2.1.1.1.1.1.1.1 R is empty

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