Certification Problem

Input (TPDB SRS_Relative/Waldmann_06_relative/r8)

The relative rewrite relation R/S is considered where R is the following TRS

a(b(a(x1))) c(c(c(x1))) (1)
c(c(c(x1))) a(c(a(x1))) (2)

and S is the following TRS.

a(x1) b(c(b(x1))) (3)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by ttt2 @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over (5 x 5)-matrices with strict dimension 1 over the naturals
[b(x1)] =
1 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 1
0 0 0 0 0
· x1 +
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
1 0 0 0 0
[a(x1)] =
1 0 0 1 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 1 0 0 0
· x1 +
0 0 0 0 0
0 0 0 0 0
1 0 0 0 0
0 0 0 0 0
1 0 0 0 0
[c(x1)] =
1 1 0 0 0
0 0 0 1 0
0 0 0 0 0
0 0 0 0 0
0 0 1 0 0
· x1 +
0 0 0 0 0
0 0 0 0 0
1 0 0 0 0
0 0 0 0 0
0 0 0 0 0
all of the following rules can be deleted.
a(b(a(x1))) c(c(c(x1))) (1)

1.1 Rule Removal

Using the linear polynomial interpretation over (3 x 3)-matrices with strict dimension 1 over the naturals
[b(x1)] =
1 0 0
0 0 0
0 0 0
· x1 +
0 0 0
0 0 0
0 0 0
[a(x1)] =
1 0 0
0 1 0
0 0 0
· x1 +
0 0 0
0 0 0
0 0 0
[c(x1)] =
1 0 1
1 1 0
0 1 0
· x1 +
0 0 0
1 0 0
0 0 0
all of the following rules can be deleted.
c(c(c(x1))) a(c(a(x1))) (2)

1.1.1 R is empty

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