Certification Problem

Input (TPDB SRS_Standard/Zantema_04/z012)

The rewrite relation of the following TRS is considered.

a(x1) b(x1) (1)
a(b(x1)) b(c(a(x1))) (2)
b(x1) c(x1) (3)
c(b(x1)) 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
[c(x1)] = x1 +
0
[b(x1)] = x1 +
1
[a(x1)] = x1 +
1
all of the following rules can be deleted.
b(x1) c(x1) (3)

1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
c#(b(x1)) a#(x1) (5)
a#(b(x1)) c#(a(x1)) (6)
a#(b(x1)) a#(x1) (7)

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 +
0
[b(x1)] = x1 +
2
[a(x1)] = x1 +
2
[c#(x1)] = x1 +
0
[a#(x1)] = x1 +
1
together with the usable rules
a(x1) b(x1) (1)
a(b(x1)) b(c(a(x1))) (2)
c(b(x1)) a(x1) (4)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
c#(b(x1)) a#(x1) (5)
a#(b(x1)) c#(a(x1)) (6)
a#(b(x1)) a#(x1) (7)
and no rules could be deleted.

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.