Certification Problem

Input (TPDB TRS_Relative/Relative_05/rt2-8)

The relative rewrite relation R/S is considered where R is the following TRS

f(act,y) f(el(nact),y) (1)
f(x,nact) f(x,act) (2)
act el(nact) (3)
l(el(x)) el(l(x)) (4)
el(r(x)) r(el(x)) (5)

and S is the following TRS.

nact l(nact) (6)
nact r(nact) (7)

Property / Task

Prove or disprove termination.

Answer / Result

No.

Proof (by AProVE @ termCOMP 2023)

1 Loop

The following loop proves that R/S is not relative terminating.

t0 = el(nact)
S el(r(nact))
R r(el(nact))
= t2
where t2 = C[t0] and C = r()