Certification Problem

Input (TPDB TRS_Standard/HirokawaMiddeldorp_04/n007)

The rewrite relation of the following TRS is considered.

f(x,y) f(x,x) (1)
f(s(x),y) f(y,x) (2)

Property / Task

Prove or disprove termination.

Answer / Result

No.

Proof (by ttt2 @ termCOMP 2023)

1 Loop

The following loop proves nontermination.

t0 = f(x,y)
f(x,x)
= t1
where t1 = t0σ and σ = {y/x, x/x}