Certification Problem

Input (TPDB SRS_Standard/Waldmann_06_SRS/sym-4)

The rewrite relation of the following TRS is considered.

b(b(x1)) c(c(c(c(x1)))) (1)
c(x1) x1 (2)
b(c(b(x1))) b(b(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 (2 x 2)-matrices with strict dimension 1 over the arctic semiring over the integers
[c(x1)] =
0 1
-∞ 0
· x1 +
-∞ -∞
-∞ -∞
[b(x1)] =
1 0
3 2
· x1 +
-∞ -∞
-∞ -∞
all of the following rules can be deleted.
b(b(x1)) c(c(c(c(x1)))) (1)

1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(c) = 1 weight(c) = 2
prec(b) = 0 weight(b) = 2
all of the following rules can be deleted.
c(x1) x1 (2)
b(c(b(x1))) b(b(b(x1))) (3)

1.1.1 R is empty

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