Certification Problem

Input (TPDB TRS_Standard/Strategy_removed_mixed_05/ex3)

The rewrite relation of the following TRS is considered.

f(g(a)) f(s(g(b))) (1)
f(f(x)) b (2)
g(x) f(g(x)) (3)

Property / Task

Prove or disprove termination.

Answer / Result

No.

Proof (by ttt2 @ termCOMP 2023)

1 Loop

The following loop proves nontermination.

t0 = g(x)
f(g(x))
= t1
where t1 = C[t0σ] and σ = {x/x} and C = f()