Certification Problem

Input (TPDB SRS_Standard/Waldmann_07_size12/size-12-alpha-3-num-52)

The rewrite relation of the following TRS is considered.

a(x1) x1 (1)
a(a(x1)) a(b(x1)) (2)
b(x1) x1 (3)
c(b(x1)) b(a(c(c(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.
c#(b(x1)) c#(x1) (5)
c#(b(x1)) c#(c(x1)) (6)
c#(b(x1)) b#(a(c(c(x1)))) (7)
c#(b(x1)) a#(c(c(x1))) (8)
a#(a(x1)) b#(x1) (9)
a#(a(x1)) a#(b(x1)) (10)

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 +
0
[a(x1)] = x1 +
0
[c#(x1)] = x1 +
2
[b#(x1)] = x1 +
0
[a#(x1)] = x1 +
1
together with the usable rules
a(x1) x1 (1)
a(a(x1)) a(b(x1)) (2)
b(x1) x1 (3)
c(b(x1)) b(a(c(c(x1)))) (4)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
c#(b(x1)) b#(a(c(c(x1)))) (7)
c#(b(x1)) a#(c(c(x1))) (8)
a#(a(x1)) b#(x1) (9)
and no rules could be deleted.

1.1.1 Dependency Graph Processor

The dependency pairs are split into 2 components.