Certification Problem

Input (TPDB SRS_Standard/Zantema_04/z009)

The rewrite relation of the following TRS is considered.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by matchbox @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
d#(c(x1)) d#(a(x1)) (5)
d#(c(x1)) a#(x1) (6)
a#(c(x1)) a#(x1) (7)
a#(b(x1)) a#(x1) (8)

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
[d(x1)] = x1 +
0
[c(x1)] = x1 +
1
[b(x1)] = x1 +
0
[a(x1)] = x1 +
1
[d#(x1)] = x1 +
1
[a#(x1)] = x1 +
0
together with the usable rules
a(x1) b(c(x1)) (1)
a(b(x1)) b(a(x1)) (2)
d(c(x1)) d(a(x1)) (3)
a(c(x1)) c(a(x1)) (4)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
d#(c(x1)) a#(x1) (6)
a#(c(x1)) a#(x1) (7)
and no rules could be deleted.

1.1.1 Dependency Graph Processor

The dependency pairs are split into 2 components.