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.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by ttt2 @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over (4 x 4)-matrices with strict dimension 1 over the naturals
[f(x1, x2)] =
1 0 1 1
0 0 0 0
0 0 1 1
0 0 0 0
· x1 +
1 0 0 0
0 0 0 0
1 1 0 0
1 0 0 0
· x2 +
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
[r(x1)] =
1 0 0 0
0 0 0 0
0 0 1 0
0 0 0 1
· x1 +
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
[el(x1)] =
1 0 0 0
0 0 0 0
0 0 0 1
1 0 1 0
· x1 +
0 0 0 0
0 0 0 0
0 0 0 0
1 0 0 0
[l(x1)] =
1 0 0 0
0 0 1 1
0 0 1 0
0 0 0 1
· x1 +
0 0 0 0
1 0 0 0
0 0 0 0
0 0 0 0
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.