Certification Problem

Input (TPDB TRS_Relative/Relative_05/rt3-5)

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

f(g(f(x))) f(g(g(g(f(x))))) (1)

and S is the following TRS.

f(x) g(g(f(g(g(x))))) (2)
g(x) g(g(f(g(g(x))))) (3)
g(x) g(g(x)) (4)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the matrix interpretations of dimension 3 with strict dimension 1 over the integers
[f(x1)] =
0
0
1
+
1 2 0
0 1 0
0 0 0
· x1
[g(x1)] =
0
0
0
+
1 0 0
0 0 2
0 0 0
· x1
all of the following rules can be deleted.
f(g(f(x))) f(g(g(g(f(x))))) (1)

1.1 R is empty

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