Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-92)

The rewrite relation of the following TRS is considered.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by matchbox @ termCOMP 2023)

1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(c(a(a(x1)))) → c(c(c(b(x1)))) (7)
c(c(a(b(x1)))) → c(c(b(a(x1)))) (8)
c(b(b(a(x1)))) → c(b(b(c(x1)))) (9)
c(b(c(b(x1)))) → c(a(a(a(x1)))) (10)
c(c(a(a(x1)))) → c(a(b(a(x1)))) (11)
c(a(b(c(x1)))) → c(a(a(c(x1)))) (12)
b(c(a(a(x1)))) → b(c(c(b(x1)))) (13)
b(c(a(b(x1)))) → b(c(b(a(x1)))) (14)
b(b(b(a(x1)))) → b(b(b(c(x1)))) (15)
b(b(c(b(x1)))) → b(a(a(a(x1)))) (16)
b(c(a(a(x1)))) → b(a(b(a(x1)))) (17)
b(a(b(c(x1)))) → b(a(a(c(x1)))) (18)
a(c(a(a(x1)))) → a(c(c(b(x1)))) (19)
a(c(a(b(x1)))) → a(c(b(a(x1)))) (20)
a(b(b(a(x1)))) → a(b(b(c(x1)))) (21)
a(b(c(b(x1)))) → a(a(a(a(x1)))) (22)
a(c(a(a(x1)))) → a(a(b(a(x1)))) (23)
a(a(b(c(x1)))) → a(a(a(c(x1)))) (24)

1.1 Closure Under Flat Contexts

Using the flat contexts

{c(☐), b(☐), a(☐)}

We obtain the transformed TRS
c(c(c(a(a(x1))))) → c(c(c(c(b(x1))))) (25)
c(c(c(a(b(x1))))) → c(c(c(b(a(x1))))) (26)
c(c(b(b(a(x1))))) → c(c(b(b(c(x1))))) (27)
c(c(b(c(b(x1))))) → c(c(a(a(a(x1))))) (28)
c(c(c(a(a(x1))))) → c(c(a(b(a(x1))))) (29)
c(c(a(b(c(x1))))) → c(c(a(a(c(x1))))) (30)
c(b(c(a(a(x1))))) → c(b(c(c(b(x1))))) (31)
c(b(c(a(b(x1))))) → c(b(c(b(a(x1))))) (32)
c(b(b(b(a(x1))))) → c(b(b(b(c(x1))))) (33)
c(b(b(c(b(x1))))) → c(b(a(a(a(x1))))) (34)
c(b(c(a(a(x1))))) → c(b(a(b(a(x1))))) (35)
c(b(a(b(c(x1))))) → c(b(a(a(c(x1))))) (36)
c(a(c(a(a(x1))))) → c(a(c(c(b(x1))))) (37)
c(a(c(a(b(x1))))) → c(a(c(b(a(x1))))) (38)
c(a(b(b(a(x1))))) → c(a(b(b(c(x1))))) (39)
c(a(b(c(b(x1))))) → c(a(a(a(a(x1))))) (40)
c(a(c(a(a(x1))))) → c(a(a(b(a(x1))))) (41)
c(a(a(b(c(x1))))) → c(a(a(a(c(x1))))) (42)
b(c(c(a(a(x1))))) → b(c(c(c(b(x1))))) (43)
b(c(c(a(b(x1))))) → b(c(c(b(a(x1))))) (44)
b(c(b(b(a(x1))))) → b(c(b(b(c(x1))))) (45)
b(c(b(c(b(x1))))) → b(c(a(a(a(x1))))) (46)
b(c(c(a(a(x1))))) → b(c(a(b(a(x1))))) (47)
b(c(a(b(c(x1))))) → b(c(a(a(c(x1))))) (48)
b(b(c(a(a(x1))))) → b(b(c(c(b(x1))))) (49)
b(b(c(a(b(x1))))) → b(b(c(b(a(x1))))) (50)
b(b(b(b(a(x1))))) → b(b(b(b(c(x1))))) (51)
b(b(b(c(b(x1))))) → b(b(a(a(a(x1))))) (52)
b(b(c(a(a(x1))))) → b(b(a(b(a(x1))))) (53)
b(b(a(b(c(x1))))) → b(b(a(a(c(x1))))) (54)
b(a(c(a(a(x1))))) → b(a(c(c(b(x1))))) (55)
b(a(c(a(b(x1))))) → b(a(c(b(a(x1))))) (56)
b(a(b(b(a(x1))))) → b(a(b(b(c(x1))))) (57)
b(a(b(c(b(x1))))) → b(a(a(a(a(x1))))) (58)
b(a(c(a(a(x1))))) → b(a(a(b(a(x1))))) (59)
b(a(a(b(c(x1))))) → b(a(a(a(c(x1))))) (60)
a(c(c(a(a(x1))))) → a(c(c(c(b(x1))))) (61)
a(c(c(a(b(x1))))) → a(c(c(b(a(x1))))) (62)
a(c(b(b(a(x1))))) → a(c(b(b(c(x1))))) (63)
a(c(b(c(b(x1))))) → a(c(a(a(a(x1))))) (64)
a(c(c(a(a(x1))))) → a(c(a(b(a(x1))))) (65)
a(c(a(b(c(x1))))) → a(c(a(a(c(x1))))) (66)
a(b(c(a(a(x1))))) → a(b(c(c(b(x1))))) (67)
a(b(c(a(b(x1))))) → a(b(c(b(a(x1))))) (68)
a(b(b(b(a(x1))))) → a(b(b(b(c(x1))))) (69)
a(b(b(c(b(x1))))) → a(b(a(a(a(x1))))) (70)
a(b(c(a(a(x1))))) → a(b(a(b(a(x1))))) (71)
a(b(a(b(c(x1))))) → a(b(a(a(c(x1))))) (72)
a(a(c(a(a(x1))))) → a(a(c(c(b(x1))))) (73)
a(a(c(a(b(x1))))) → a(a(c(b(a(x1))))) (74)
a(a(b(b(a(x1))))) → a(a(b(b(c(x1))))) (75)
a(a(b(c(b(x1))))) → a(a(a(a(a(x1))))) (76)
a(a(c(a(a(x1))))) → a(a(a(b(a(x1))))) (77)
a(a(a(b(c(x1))))) → a(a(a(a(c(x1))))) (78)

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 486 ruless (increase limit for explicit display).

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 +
0
[c3(x1)] = x1 +
14
[c6(x1)] = x1 +
0
[c1(x1)] = x1 +
246
[c4(x1)] = x1 +
60
[c7(x1)] = x1 +
0
[c2(x1)] = x1 +
245
[c5(x1)] = x1 +
245
[c8(x1)] = x1 +
304
[b0(x1)] = x1 +
0
[b3(x1)] = x1 +
246
[b6(x1)] = x1 +
13
[b1(x1)] = x1 +
60
[b4(x1)] = x1 +
246
[b7(x1)] = x1 +
291
[b2(x1)] = x1 +
26
[b5(x1)] = x1 +
4
[b8(x1)] = x1 +
41
[a0(x1)] = x1 +
46
[a3(x1)] = x1 +
245
[a6(x1)] = x1 +
50
[a1(x1)] = x1 +
258
[a4(x1)] = x1 +
246
[a7(x1)] = x1 +
50
[a2(x1)] = x1 +
46
[a5(x1)] = x1 +
13
[a8(x1)] = x1 +
46
all of the following rules can be deleted.

There are 486 ruless (increase limit for explicit display).

1.1.1.1.1 R is empty

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