Certification Problem

Input (TPDB TRS_Innermost/Mixed_innermost/test830)

The rewrite relation of the following TRS is considered.

f(s(X)) f(X) (1)
g(cons(0,Y)) g(Y) (2)
g(cons(s(X),Y)) s(X) (3)
h(cons(X,Y)) h(g(cons(X,Y))) (4)
The evaluation strategy is innermost.

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over the naturals
[f(x1)] = 2 · x1
[s(x1)] = 2 · x1
[g(x1)] = 1 · x1
[cons(x1, x2)] = 1 · x1 + 1 · x2
[0] = 2
[h(x1)] = 2 · x1
all of the following rules can be deleted.
g(cons(0,Y)) g(Y) (2)

1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[f(x1)] = 2 · x1
[s(x1)] = 1 + 1 · x1
[g(x1)] = 1 · x1
[cons(x1, x2)] = 1 · x1 + 2 · x2
[h(x1)] = 1 · x1
all of the following rules can be deleted.
f(s(X)) f(X) (1)

1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[g(x1)] = 1 · x1
[cons(x1, x2)] = 1 + 1 · x1 + 1 · x2
[s(x1)] = 1 + 2 · x1
[h(x1)] = 1 · x1
all of the following rules can be deleted.
g(cons(s(X),Y)) s(X) (3)

1.1.1.1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
h#(cons(X,Y)) h#(g(cons(X,Y))) (5)

1.1.1.1.1 Usable Rules Processor

We restrict the rewrite rules to the following usable rules of the DP problem.

There are no rules.

1.1.1.1.1.1 Innermost Lhss Removal Processor

We restrict the innermost strategy to the following left hand sides.

g(cons(0,x0))
g(cons(s(x0),x1))

1.1.1.1.1.1.1 Reduction Pair Processor

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(cons) = 1 weight(cons) = 1
prec(g) = 0 weight(g) = 1
in combination with the following argument filter

π(h#) = 1
π(cons) = []
π(g) = []

the pair
h#(cons(X,Y)) h#(g(cons(X,Y))) (5)
could be deleted.

1.1.1.1.1.1.1.1 P is empty

There are no pairs anymore.