Certification Problem

Input (TPDB SRS_Standard/Zantema_04/z084)

The rewrite relation of the following TRS is considered.

b(c(x1)) a(x1) (1)
b(b(x1)) a(c(x1)) (2)
a(x1) c(b(x1)) (3)
c(c(c(x1))) b(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 +
2
[b(x1)] = x1 +
5
[a(x1)] = x1 +
7
all of the following rules can be deleted.
b(b(x1)) a(c(x1)) (2)
c(c(c(x1))) b(x1) (4)

1.1 Dependency Pair Transformation

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

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 +
2
[b(x1)] = x1 +
0
[a(x1)] = x1 +
2
[b#(x1)] = x1 +
0
[a#(x1)] = x1 +
1
together with the usable rules
b(c(x1)) a(x1) (1)
a(x1) c(b(x1)) (3)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
b#(c(x1)) a#(x1) (5)
a#(x1) b#(x1) (6)
and no rules could be deleted.

1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.