Certification Problem

Input (TPDB SRS_Standard/Zantema_04/z109)

The rewrite relation of the following TRS is considered.

a(a(a(x1))) b(b(x1)) (1)
b(b(b(x1))) c(x1) (2)
c(x1) d(d(x1)) (3)
d(x1) a(a(x1)) (4)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by matchbox @ termCOMP 2023)

1 Rule Removal

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[d(x1)] = x1 +
35
[c(x1)] = x1 +
71
[b(x1)] = x1 +
24
[a(x1)] = x1 +
17
all of the following rules can be deleted.
a(a(a(x1))) b(b(x1)) (1)
b(b(b(x1))) c(x1) (2)
c(x1) d(d(x1)) (3)
d(x1) a(a(x1)) (4)

1.1 R is empty

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