Certification Problem

Input (TPDB SRS_Standard/Waldmann_06_SRS/uni-6)

The rewrite relation of the following TRS is considered.

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

Property / Task

Prove or disprove termination.

Answer / Result

No.

Proof (by matchbox @ termCOMP 2023)

1 Loop

The following loop proves nontermination.

t0 = c(c(c(b(b(b(b(x1)))))))
a(b(b(b(b(b(b(x1)))))))
a(c(c(c(b(b(b(x1)))))))
a(a(b(b(b(b(b(x1)))))))
a(a(c(c(c(b(b(x1)))))))
a(a(a(b(b(b(b(x1)))))))
c(c(b(b(b(b(b(x1)))))))
c(c(c(c(c(b(b(x1)))))))
c(c(a(b(b(b(b(x1)))))))
c(c(a(c(c(c(b(x1)))))))
c(c(a(a(b(b(b(x1)))))))
c(c(a(a(c(c(c(x1)))))))
c(c(a(a(a(b(b(x1)))))))
c(c(c(c(b(b(b(x1)))))))
c(a(b(b(b(b(b(x1)))))))
c(a(c(c(c(b(b(x1)))))))
c(a(a(b(b(b(b(x1)))))))
c(a(a(c(c(c(b(x1)))))))
c(a(a(a(b(b(b(x1)))))))
c(c(c(b(b(b(b(x1)))))))
= t19
where t19 = t0σ and σ = {x1/x1}