Certification Problem

Input (TPDB SRS_Standard/Zantema_04/z093)

The rewrite relation of the following TRS is considered.

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

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
[c(x1)] = x1 +
8
[b(x1)] = x1 +
8
[a(x1)] = x1 +
5
all of the following rules can be deleted.
c(b(x1)) a(a(a(x1))) (2)
a(a(a(a(x1)))) b(c(x1)) (3)

1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
b#(c(x1)) b#(x1) (4)

1.1.1 Monotonic Reduction Pair Processor with Usable Rules

Using the matrix interpretations of dimension 1 with strict dimension 1 over the rationals with delta = 1
[c(x1)] = x1 +
1
[b(x1)] = x1 +
0
[b#(x1)] = x1 +
0
together with the usable rule
b(c(x1)) c(b(x1)) (1)
(w.r.t. the implicit argument filter of the reduction pair), the pair
b#(c(x1)) b#(x1) (4)
and no rules could be deleted.

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.