Certification Problem

Input (TPDB TRS_Relative/Relative_05/rt1-4)

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

f(el(x),y) f(x,el(y)) (1)

and S is the following TRS.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the
prec(f) = 1 stat(f) = lex
prec(el) = 0 stat(el) = lex

π(f) = [1,2]
π(el) = [1]
π(l) = 1
π(r) = 1

all of the following rules can be deleted.
f(el(x),y) f(x,el(y)) (1)

1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.