NO Problem: g(x,x,y) -> y g(x,y,y) -> x f(x,y,x,y,z) -> f(a(),b(),z,z,z) a() -> 0() b() -> 0() Proof: Unfolding Processor: loop length: 3 terms: f(0(),0(),0(),0(),0()) f(a(),b(),0(),0(),0()) f(0(),b(),0(),0(),0()) context: [] substitution: Qed