Certification Problem

Input (TPDB SRS_Standard/Trafo_06/dup06)

The rewrite relation of the following TRS is considered.

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

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.
b#(b(c(c(x1)))) b#(x1) (4)
b#(b(c(c(x1)))) b#(b(x1)) (5)
b#(b(c(c(x1)))) b#(b(b(x1))) (6)
b#(b(c(c(x1)))) b#(b(b(b(x1)))) (7)
b#(b(a(a(x1)))) b#(x1) (8)
b#(b(a(a(x1)))) b#(b(x1)) (9)
b#(b(a(a(x1)))) a#(c(c(b(b(x1))))) (10)
b#(b(a(a(x1)))) a#(a(c(c(b(b(x1)))))) (11)
a#(a(b(b(x1)))) b#(c(c(a(a(x1))))) (12)
a#(a(b(b(x1)))) b#(b(c(c(a(a(x1)))))) (13)
a#(a(b(b(x1)))) a#(x1) (14)
a#(a(b(b(x1)))) a#(a(x1)) (15)

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 +
1
[b#(x1)] = x1 +
0
[a#(x1)] = x1 +
1
together with the usable rules
a(a(b(b(x1)))) b(b(c(c(a(a(x1)))))) (1)
b(b(c(c(x1)))) c(c(b(b(b(b(x1)))))) (2)
b(b(a(a(x1)))) a(a(c(c(b(b(x1)))))) (3)
(w.r.t. the implicit argument filter of the reduction pair), the pairs
b#(b(a(a(x1)))) b#(x1) (8)
b#(b(a(a(x1)))) b#(b(x1)) (9)
b#(b(a(a(x1)))) a#(c(c(b(b(x1))))) (10)
a#(a(b(b(x1)))) a#(x1) (14)
and no rules could be deleted.

1.1.1 Dependency Graph Processor

The dependency pairs are split into 2 components.