Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-77)

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

b(b(c(x1))) c(a(c(x1))) (1)
a(c(b(x1))) b(c(c(x1))) (2)
b(b(b(x1))) b(c(a(x1))) (3)

and S is the following TRS.

b(a(a(x1))) c(c(c(x1))) (4)
a(a(b(x1))) b(a(a(x1))) (5)
c(a(b(x1))) b(b(a(x1))) (6)
b(a(a(x1))) c(c(b(x1))) (7)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by ttt2 @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over the naturals
[b(x1)] = 2 · x1 + 9
[c(x1)] = 2 · x1 + 7
[a(x1)] = 2 · x1 + 8
all of the following rules can be deleted.
b(b(c(x1))) c(a(c(x1))) (1)
a(c(b(x1))) b(c(c(x1))) (2)
b(b(b(x1))) b(c(a(x1))) (3)
b(a(a(x1))) c(c(c(x1))) (4)
a(a(b(x1))) b(a(a(x1))) (5)

1.1 R is empty

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