YES Problem: a(c(d(x))) -> c(x) u(b(d(d(x)))) -> b(x) v(a(a(x))) -> u(v(x)) v(a(c(x))) -> u(b(d(x))) v(c(x)) -> b(x) w(a(a(x))) -> u(w(x)) w(a(c(x))) -> u(b(d(x))) w(c(x)) -> b(x) Proof: Arctic Interpretation Processor: dimension: 1 interpretation: [w](x0) = x0, [v](x0) = x0, [u](x0) = x0, [b](x0) = x0, [a](x0) = x0, [c](x0) = 9x0, [d](x0) = 2x0 orientation: a(c(d(x))) = 11x >= 9x = c(x) u(b(d(d(x)))) = 4x >= x = b(x) v(a(a(x))) = x >= x = u(v(x)) v(a(c(x))) = 9x >= 2x = u(b(d(x))) v(c(x)) = 9x >= x = b(x) w(a(a(x))) = x >= x = u(w(x)) w(a(c(x))) = 9x >= 2x = u(b(d(x))) w(c(x)) = 9x >= x = b(x) problem: v(a(a(x))) -> u(v(x)) w(a(a(x))) -> u(w(x)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 1] [w](x0) = [0 0]x0, [0 0 ] [v](x0) = [-& 0 ]x0, [0 0] [u](x0) = [0 0]x0, [1 -&] [a](x0) = [1 2 ]x0 orientation: [3 4] [0 0] v(a(a(x))) = [3 4]x >= [0 0]x = u(v(x)) [4 5] [0 1] w(a(a(x))) = [3 4]x >= [0 1]x = u(w(x)) problem: Qed