Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-172)

The rewrite relation of the following TRS is considered.

a(a(c(x1))) b(b(c(x1))) (1)
b(a(c(x1))) a(a(b(x1))) (2)
a(c(a(x1))) a(b(b(x1))) (3)
b(b(b(x1))) c(c(b(x1))) (4)
b(a(c(x1))) a(a(c(x1))) (5)
c(a(a(x1))) a(a(a(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(a(a(c(x1)))) c(b(b(c(x1)))) (7)
c(b(a(c(x1)))) c(a(a(b(x1)))) (8)
c(a(c(a(x1)))) c(a(b(b(x1)))) (9)
c(b(b(b(x1)))) c(c(c(b(x1)))) (10)
c(b(a(c(x1)))) c(a(a(c(x1)))) (11)
c(c(a(a(x1)))) c(a(a(a(x1)))) (12)
b(a(a(c(x1)))) b(b(b(c(x1)))) (13)
b(b(a(c(x1)))) b(a(a(b(x1)))) (14)
b(a(c(a(x1)))) b(a(b(b(x1)))) (15)
b(b(b(b(x1)))) b(c(c(b(x1)))) (16)
b(b(a(c(x1)))) b(a(a(c(x1)))) (17)
b(c(a(a(x1)))) b(a(a(a(x1)))) (18)
a(a(a(c(x1)))) a(b(b(c(x1)))) (19)
a(b(a(c(x1)))) a(a(a(b(x1)))) (20)
a(a(c(a(x1)))) a(a(b(b(x1)))) (21)
a(b(b(b(x1)))) a(c(c(b(x1)))) (22)
a(b(a(c(x1)))) a(a(a(c(x1)))) (23)
a(c(a(a(x1)))) a(a(a(a(x1)))) (24)

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(b1(b0(c2(x1)))) (25)
a2(a2(a0(c0(x1)))) a1(b1(b0(c0(x1)))) (26)
a2(a2(a0(c1(x1)))) a1(b1(b0(c1(x1)))) (27)
c2(a2(a0(c2(x1)))) c1(b1(b0(c2(x1)))) (28)
c2(a2(a0(c0(x1)))) c1(b1(b0(c0(x1)))) (29)
c2(a2(a0(c1(x1)))) c1(b1(b0(c1(x1)))) (30)
b2(a2(a0(c2(x1)))) b1(b1(b0(c2(x1)))) (31)
b2(a2(a0(c0(x1)))) b1(b1(b0(c0(x1)))) (32)
b2(a2(a0(c1(x1)))) b1(b1(b0(c1(x1)))) (33)
a1(b2(a0(c2(x1)))) a2(a2(a1(b2(x1)))) (34)
a1(b2(a0(c0(x1)))) a2(a2(a1(b0(x1)))) (35)
a1(b2(a0(c1(x1)))) a2(a2(a1(b1(x1)))) (36)
c1(b2(a0(c2(x1)))) c2(a2(a1(b2(x1)))) (37)
c1(b2(a0(c0(x1)))) c2(a2(a1(b0(x1)))) (38)
c1(b2(a0(c1(x1)))) c2(a2(a1(b1(x1)))) (39)
b1(b2(a0(c2(x1)))) b2(a2(a1(b2(x1)))) (40)
b1(b2(a0(c0(x1)))) b2(a2(a1(b0(x1)))) (41)
b1(b2(a0(c1(x1)))) b2(a2(a1(b1(x1)))) (42)
a2(a0(c2(a2(x1)))) a2(a1(b1(b2(x1)))) (43)
a2(a0(c2(a0(x1)))) a2(a1(b1(b0(x1)))) (44)
a2(a0(c2(a1(x1)))) a2(a1(b1(b1(x1)))) (45)
c2(a0(c2(a2(x1)))) c2(a1(b1(b2(x1)))) (46)
c2(a0(c2(a0(x1)))) c2(a1(b1(b0(x1)))) (47)
c2(a0(c2(a1(x1)))) c2(a1(b1(b1(x1)))) (48)
b2(a0(c2(a2(x1)))) b2(a1(b1(b2(x1)))) (49)
b2(a0(c2(a0(x1)))) b2(a1(b1(b0(x1)))) (50)
b2(a0(c2(a1(x1)))) b2(a1(b1(b1(x1)))) (51)
a1(b1(b1(b2(x1)))) a0(c0(c1(b2(x1)))) (52)
a1(b1(b1(b0(x1)))) a0(c0(c1(b0(x1)))) (53)
a1(b1(b1(b1(x1)))) a0(c0(c1(b1(x1)))) (54)
c1(b1(b1(b2(x1)))) c0(c0(c1(b2(x1)))) (55)
c1(b1(b1(b0(x1)))) c0(c0(c1(b0(x1)))) (56)
c1(b1(b1(b1(x1)))) c0(c0(c1(b1(x1)))) (57)
b1(b1(b1(b2(x1)))) b0(c0(c1(b2(x1)))) (58)
b1(b1(b1(b0(x1)))) b0(c0(c1(b0(x1)))) (59)
b1(b1(b1(b1(x1)))) b0(c0(c1(b1(x1)))) (60)
a1(b2(a0(c2(x1)))) a2(a2(a0(c2(x1)))) (61)
a1(b2(a0(c0(x1)))) a2(a2(a0(c0(x1)))) (62)
a1(b2(a0(c1(x1)))) a2(a2(a0(c1(x1)))) (63)
c1(b2(a0(c2(x1)))) c2(a2(a0(c2(x1)))) (64)
c1(b2(a0(c0(x1)))) c2(a2(a0(c0(x1)))) (65)
c1(b2(a0(c1(x1)))) c2(a2(a0(c1(x1)))) (66)
b1(b2(a0(c2(x1)))) b2(a2(a0(c2(x1)))) (67)
b1(b2(a0(c0(x1)))) b2(a2(a0(c0(x1)))) (68)
b1(b2(a0(c1(x1)))) b2(a2(a0(c1(x1)))) (69)
a0(c2(a2(a2(x1)))) a2(a2(a2(a2(x1)))) (70)
a0(c2(a2(a0(x1)))) a2(a2(a2(a0(x1)))) (71)
a0(c2(a2(a1(x1)))) a2(a2(a2(a1(x1)))) (72)
c0(c2(a2(a2(x1)))) c2(a2(a2(a2(x1)))) (73)
c0(c2(a2(a0(x1)))) c2(a2(a2(a0(x1)))) (74)
c0(c2(a2(a1(x1)))) c2(a2(a2(a1(x1)))) (75)
b0(c2(a2(a2(x1)))) b2(a2(a2(a2(x1)))) (76)
b0(c2(a2(a0(x1)))) b2(a2(a2(a0(x1)))) (77)
b0(c2(a2(a1(x1)))) b2(a2(a2(a1(x1)))) (78)

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 +
3
[c1(x1)] = x1 +
8
[c2(x1)] = x1 +
14
[b0(x1)] = x1 +
0
[b1(x1)] = x1 +
10
[b2(x1)] = x1 +
11
[a0(x1)] = x1 +
8
[a1(x1)] = x1 +
0
[a2(x1)] = x1 +
2
all of the following rules can be deleted.
a2(a2(a0(c2(x1)))) a1(b1(b0(c2(x1)))) (25)
a2(a2(a0(c0(x1)))) a1(b1(b0(c0(x1)))) (26)
a2(a2(a0(c1(x1)))) a1(b1(b0(c1(x1)))) (27)
c2(a2(a0(c2(x1)))) c1(b1(b0(c2(x1)))) (28)
c2(a2(a0(c0(x1)))) c1(b1(b0(c0(x1)))) (29)
c2(a2(a0(c1(x1)))) c1(b1(b0(c1(x1)))) (30)
b2(a2(a0(c2(x1)))) b1(b1(b0(c2(x1)))) (31)
b2(a2(a0(c0(x1)))) b1(b1(b0(c0(x1)))) (32)
b2(a2(a0(c1(x1)))) b1(b1(b0(c1(x1)))) (33)
a1(b2(a0(c2(x1)))) a2(a2(a1(b2(x1)))) (34)
a1(b2(a0(c0(x1)))) a2(a2(a1(b0(x1)))) (35)
a1(b2(a0(c1(x1)))) a2(a2(a1(b1(x1)))) (36)
c1(b2(a0(c2(x1)))) c2(a2(a1(b2(x1)))) (37)
c1(b2(a0(c0(x1)))) c2(a2(a1(b0(x1)))) (38)
c1(b2(a0(c1(x1)))) c2(a2(a1(b1(x1)))) (39)
b1(b2(a0(c2(x1)))) b2(a2(a1(b2(x1)))) (40)
b1(b2(a0(c0(x1)))) b2(a2(a1(b0(x1)))) (41)
b1(b2(a0(c1(x1)))) b2(a2(a1(b1(x1)))) (42)
a2(a0(c2(a2(x1)))) a2(a1(b1(b2(x1)))) (43)
a2(a0(c2(a0(x1)))) a2(a1(b1(b0(x1)))) (44)
a2(a0(c2(a1(x1)))) a2(a1(b1(b1(x1)))) (45)
c2(a0(c2(a2(x1)))) c2(a1(b1(b2(x1)))) (46)
c2(a0(c2(a0(x1)))) c2(a1(b1(b0(x1)))) (47)
c2(a0(c2(a1(x1)))) c2(a1(b1(b1(x1)))) (48)
b2(a0(c2(a2(x1)))) b2(a1(b1(b2(x1)))) (49)
b2(a0(c2(a0(x1)))) b2(a1(b1(b0(x1)))) (50)
b2(a0(c2(a1(x1)))) b2(a1(b1(b1(x1)))) (51)
a1(b1(b1(b2(x1)))) a0(c0(c1(b2(x1)))) (52)
a1(b1(b1(b0(x1)))) a0(c0(c1(b0(x1)))) (53)
a1(b1(b1(b1(x1)))) a0(c0(c1(b1(x1)))) (54)
c1(b1(b1(b2(x1)))) c0(c0(c1(b2(x1)))) (55)
c1(b1(b1(b0(x1)))) c0(c0(c1(b0(x1)))) (56)
c1(b1(b1(b1(x1)))) c0(c0(c1(b1(x1)))) (57)
b1(b1(b1(b2(x1)))) b0(c0(c1(b2(x1)))) (58)
b1(b1(b1(b0(x1)))) b0(c0(c1(b0(x1)))) (59)
b1(b1(b1(b1(x1)))) b0(c0(c1(b1(x1)))) (60)
a1(b2(a0(c2(x1)))) a2(a2(a0(c2(x1)))) (61)
a1(b2(a0(c0(x1)))) a2(a2(a0(c0(x1)))) (62)
a1(b2(a0(c1(x1)))) a2(a2(a0(c1(x1)))) (63)
c1(b2(a0(c2(x1)))) c2(a2(a0(c2(x1)))) (64)
c1(b2(a0(c0(x1)))) c2(a2(a0(c0(x1)))) (65)
c1(b2(a0(c1(x1)))) c2(a2(a0(c1(x1)))) (66)
b1(b2(a0(c2(x1)))) b2(a2(a0(c2(x1)))) (67)
b1(b2(a0(c0(x1)))) b2(a2(a0(c0(x1)))) (68)
b1(b2(a0(c1(x1)))) b2(a2(a0(c1(x1)))) (69)
a0(c2(a2(a2(x1)))) a2(a2(a2(a2(x1)))) (70)
a0(c2(a2(a0(x1)))) a2(a2(a2(a0(x1)))) (71)
a0(c2(a2(a1(x1)))) a2(a2(a2(a1(x1)))) (72)
c0(c2(a2(a2(x1)))) c2(a2(a2(a2(x1)))) (73)
c0(c2(a2(a0(x1)))) c2(a2(a2(a0(x1)))) (74)
c0(c2(a2(a1(x1)))) c2(a2(a2(a1(x1)))) (75)
b0(c2(a2(a2(x1)))) b2(a2(a2(a2(x1)))) (76)
b0(c2(a2(a0(x1)))) b2(a2(a2(a0(x1)))) (77)
b0(c2(a2(a1(x1)))) b2(a2(a2(a1(x1)))) (78)

1.1.1.1 R is empty

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