NO Problem: f(b()) -> a() f(b()) -> f(c()) f(c()) -> f(b()) f(c()) -> d() b() -> e() c() -> e'() f(e()) -> a() f(e'()) -> d() Proof: Matrix Interpretation Processor: dimension: 3 interpretation: [0] [e'] = [0] [0], [0] [e] = [0] [0], [0] [d] = [0] [0], [1] [c] = [0] [0], [0] [a] = [0] [0], [1 0 0] [f](x0) = [0 0 0]x0 [0 0 0] , [1] [b] = [0] [0] orientation: [1] [0] f(b()) = [0] >= [0] = a() [0] [0] [1] [1] f(b()) = [0] >= [0] = f(c()) [0] [0] [1] [1] f(c()) = [0] >= [0] = f(b()) [0] [0] [1] [0] f(c()) = [0] >= [0] = d() [0] [0] [1] [0] b() = [0] >= [0] = e() [0] [0] [1] [0] c() = [0] >= [0] = e'() [0] [0] [0] [0] f(e()) = [0] >= [0] = a() [0] [0] [0] [0] f(e'()) = [0] >= [0] = d() [0] [0] problem: f(b()) -> f(c()) f(c()) -> f(b()) f(e()) -> a() f(e'()) -> d() Matrix Interpretation Processor: dimension: 3 interpretation: [0] [e'] = [0] [1], [0] [e] = [0] [1], [0] [d] = [0] [0], [0] [c] = [0] [0], [0] [a] = [0] [0], [1 0 1] [f](x0) = [0 0 0]x0 [0 0 0] , [0] [b] = [0] [0] orientation: [0] [0] f(b()) = [0] >= [0] = f(c()) [0] [0] [0] [0] f(c()) = [0] >= [0] = f(b()) [0] [0] [1] [0] f(e()) = [0] >= [0] = a() [0] [0] [1] [0] f(e'()) = [0] >= [0] = d() [0] [0] problem: f(b()) -> f(c()) f(c()) -> f(b()) Unfolding Processor: loop length: 2 terms: f(b()) f(c()) context: [] substitution: Qed