YES Problem: a(p(x1)) -> p(a(A(x1))) a(A(x1)) -> A(a(x1)) p(A(A(x1))) -> a(p(x1)) Proof: String Reversal Processor: p(a(x1)) -> A(a(p(x1))) A(a(x1)) -> a(A(x1)) A(A(p(x1))) -> p(a(x1)) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [1] [A](x0) = [0 1 0]x0 + [1] [0 1 0] [0], [0] [a](x0) = x0 + [1] [1], [1 1 0] [0] [p](x0) = [0 1 1]x0 + [1] [0 1 1] [0] orientation: [1 1 0] [1] [1 1 0] [1] p(a(x1)) = [0 1 1]x1 + [3] >= [0 1 1]x1 + [3] = A(a(p(x1))) [0 1 1] [2] [0 1 1] [2] [1 0 0] [1] [1 0 0] [1] A(a(x1)) = [0 1 0]x1 + [2] >= [0 1 0]x1 + [2] = a(A(x1)) [0 1 0] [1] [0 1 0] [1] [1 1 0] [2] [1 1 0] [1] A(A(p(x1))) = [0 1 1]x1 + [3] >= [0 1 1]x1 + [3] = p(a(x1)) [0 1 1] [2] [0 1 1] [2] problem: p(a(x1)) -> A(a(p(x1))) A(a(x1)) -> a(A(x1)) String Reversal Processor: a(p(x1)) -> p(a(A(x1))) a(A(x1)) -> A(a(x1)) Bounds Processor: bound: 1 enrichment: match automaton: final states: {5,1} transitions: A1(8) -> 9* a1(7) -> 8* f30() -> 2* p0(4) -> 1* a0(2) -> 6* a0(3) -> 4* A0(2) -> 3* A0(6) -> 5* 1 -> 8,6 2 -> 7* 5 -> 8,6 9 -> 4* problem: Qed