Certification Problem

Input (TPDB TRS_Standard/Secret_06_TRS/gen-17)

The rewrite relation of the following TRS is considered.

f(c(c(a,y,a),b(x,z),a)) b(y,f(c(f(a),z,z))) (1)
f(b(b(x,f(y)),z)) c(z,x,f(b(b(f(a),y),y))) (2)
c(b(a,a),b(y,z),x) b(a,b(z,z)) (3)

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(c) = 1 stat(c) = lex
prec(a) = 0 stat(a) = lex
prec(b) = 0 stat(b) = lex

π(f) = [1]
π(c) = [1,3,2]
π(a) = []
π(b) = [2,1]

all of the following rules can be deleted.
f(c(c(a,y,a),b(x,z),a)) b(y,f(c(f(a),z,z))) (1)
f(b(b(x,f(y)),z)) c(z,x,f(b(b(f(a),y),y))) (2)
c(b(a,a),b(y,z),x) b(a,b(z,z)) (3)

1.1 R is empty

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