YES * Step 1: Looptree YES + Considered Problem: Rules: 0. start(A,B) -> ack(A,B) True (1,1) 1. ack(A,B) -> ack(A,-1 + B) [A >= 1 && B >= 1] (?,1) 2. ack(A,B) -> ack(-1 + A,C) [A >= 1 && B >= 1] (?,1) Signature: {(ack,2);(start,2)} Flow Graph: [0->{1,2},1->{1,2},2->{1,2}] + Applied Processor: Looptree + Details: We construct a looptree: P: [0,1,2] | `- p:[1,2] c: [2] | `- p:[1] c: [1] YES