Certification Problem

Input (TPDB TRS_Standard/Various_04/03)

The rewrite relation of the following TRS is considered.

f(g(x),h(x),y,x) f(y,y,y,x) (1)
f(x,y,z,0) 2 (2)
g(0) 2 (3)
h(0) 2 (4)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
f#(g(x),h(x),y,x) f#(y,y,y,x) (5)

1.1 Size-Change Termination

Using size-change termination in combination with the subterm criterion one obtains the following initial size-change graphs.

f#(g(x),h(x),y,x) f#(y,y,y,x) (5)
3 1
3 2
3 3
1 > 4
2 > 4
4 4

As there is no critical graph in the transitive closure, there are no infinite chains.