Certification Problem

Input (TPDB SRS_Standard/ICFP_2010/3336)

The rewrite relation of the following TRS is considered.

2(5(x1)) → 1(3(3(0(1(0(x1)))))) (1)
2(5(x1)) → 2(2(0(5(0(1(x1)))))) (2)
3(5(x1)) → 1(3(2(0(0(1(x1)))))) (3)
3(5(x1)) → 3(2(0(5(3(0(x1)))))) (4)
4(5(x1)) → 2(2(1(3(2(1(x1)))))) (5)
4(5(x1)) → 3(2(0(5(0(0(x1)))))) (6)
1(2(5(x1))) → 1(0(5(0(5(4(x1)))))) (7)
1(2(5(x1))) → 1(2(2(1(0(1(x1)))))) (8)
1(2(5(x1))) → 2(0(1(3(1(0(x1)))))) (9)
1(4(5(x1))) → 1(2(4(0(2(1(x1)))))) (10)
2(5(1(x1))) → 2(2(2(1(2(3(x1)))))) (11)
2(5(2(x1))) → 4(0(2(2(3(3(x1)))))) (12)
2(5(3(x1))) → 2(0(4(1(3(3(x1)))))) (13)
2(5(4(x1))) → 2(0(5(1(0(1(x1)))))) (14)
3(2(5(x1))) → 3(2(0(1(0(5(x1)))))) (15)
3(4(2(x1))) → 3(4(0(2(2(2(x1)))))) (16)
3(5(1(x1))) → 0(4(2(0(0(5(x1)))))) (17)
3(5(1(x1))) → 0(4(2(2(3(4(x1)))))) (18)
3(5(1(x1))) → 2(1(4(1(0(1(x1)))))) (19)
3(5(2(x1))) → 0(4(3(2(2(2(x1)))))) (20)
3(5(2(x1))) → 2(0(2(2(3(0(x1)))))) (21)
3(5(2(x1))) → 2(3(3(2(1(2(x1)))))) (22)
3(5(3(x1))) → 0(2(4(3(3(0(x1)))))) (23)
3(5(3(x1))) → 0(5(4(3(3(0(x1)))))) (24)
3(5(3(x1))) → 2(3(4(0(4(2(x1)))))) (25)
3(5(4(x1))) → 0(2(0(5(0(0(x1)))))) (26)
3(5(4(x1))) → 0(5(0(0(1(2(x1)))))) (27)
3(5(5(x1))) → 0(5(4(1(0(5(x1)))))) (28)
4(5(1(x1))) → 2(1(0(5(3(3(x1)))))) (29)
4(5(2(x1))) → 0(5(1(0(0(4(x1)))))) (30)
4(5(4(x1))) → 2(2(1(0(4(2(x1)))))) (31)
4(5(4(x1))) → 3(2(0(3(2(0(x1)))))) (32)
5(5(3(x1))) → 5(1(0(1(2(2(x1)))))) (33)
5(5(4(x1))) → 5(1(0(4(2(2(x1)))))) (34)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by matchbox @ termCOMP 2023)

1 Closure Under Flat Contexts

Using the flat contexts

{5(☐), 4(☐), 3(☐), 2(☐), 1(☐), 0(☐)}

We obtain the transformed TRS

There are 204 ruless (increase limit for explicit display).

1.1 Semantic Labeling

The following interpretations form a model of the rules.

As carrier we take the set {0,...,5}. Symbols are labeled by the interpretation of their arguments using the interpretations (modulo 6):

[5(x1)] = 6x1 + 0
[4(x1)] = 6x1 + 1
[3(x1)] = 6x1 + 2
[2(x1)] = 6x1 + 3
[1(x1)] = 6x1 + 4
[0(x1)] = 6x1 + 5

We obtain the labeled TRS

There are 1224 ruless (increase limit for explicit display).

1.1.1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[50(x1)] = x1 +
5
[51(x1)] = x1 +
4
[52(x1)] = x1 +
4
[53(x1)] = x1 +
5
[54(x1)] = x1 +
4
[55(x1)] = x1 +
0
[40(x1)] = x1 +
4
[41(x1)] = x1 +
4
[42(x1)] = x1 +
0
[43(x1)] = x1 +
1
[44(x1)] = x1 +
0
[45(x1)] = x1 +
0
[30(x1)] = x1 +
5
[31(x1)] = x1 +
1
[32(x1)] = x1 +
0
[33(x1)] = x1 +
0
[34(x1)] = x1 +
0
[35(x1)] = x1 +
0
[20(x1)] = x1 +
5
[21(x1)] = x1 +
1
[22(x1)] = x1 +
0
[23(x1)] = x1 +
0
[24(x1)] = x1 +
0
[25(x1)] = x1 +
0
[10(x1)] = x1 +
4
[11(x1)] = x1 +
4
[12(x1)] = x1 +
0
[13(x1)] = x1 +
1
[14(x1)] = x1 +
0
[15(x1)] = x1 +
0
[00(x1)] = x1 +
0
[01(x1)] = x1 +
0
[02(x1)] = x1 +
0
[03(x1)] = x1 +
0
[04(x1)] = x1 +
0
[05(x1)] = x1 +
0
all of the following rules can be deleted.

There are 1224 ruless (increase limit for explicit display).

1.1.1.1 R is empty

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