YES Problem: a(b(x)) -> b(a(a(x))) b(c(x)) -> c(b(b(x))) c(a(x)) -> a(c(c(x))) u(a(x)) -> x v(b(x)) -> x w(c(x)) -> x a(u(x)) -> x b(v(x)) -> x c(w(x)) -> x Proof: DP Processor: DPs: a#(b(x)) -> a#(x) a#(b(x)) -> a#(a(x)) a#(b(x)) -> b#(a(a(x))) b#(c(x)) -> b#(x) b#(c(x)) -> b#(b(x)) b#(c(x)) -> c#(b(b(x))) c#(a(x)) -> c#(x) c#(a(x)) -> c#(c(x)) c#(a(x)) -> a#(c(c(x))) TRS: a(b(x)) -> b(a(a(x))) b(c(x)) -> c(b(b(x))) c(a(x)) -> a(c(c(x))) u(a(x)) -> x v(b(x)) -> x w(c(x)) -> x a(u(x)) -> x b(v(x)) -> x c(w(x)) -> x Usable Rule Processor: DPs: a#(b(x)) -> a#(x) a#(b(x)) -> a#(a(x)) a#(b(x)) -> b#(a(a(x))) b#(c(x)) -> b#(x) b#(c(x)) -> b#(b(x)) b#(c(x)) -> c#(b(b(x))) c#(a(x)) -> c#(x) c#(a(x)) -> c#(c(x)) c#(a(x)) -> a#(c(c(x))) TRS: a(b(x)) -> b(a(a(x))) a(u(x)) -> x b(c(x)) -> c(b(b(x))) b(v(x)) -> x c(a(x)) -> a(c(c(x))) c(w(x)) -> x Matrix Interpretation Processor: dim=5 interpretation: [c#](x0) = [1 0 1 0 0]x0, [b#](x0) = [0 1 0 0 1]x0, [a#](x0) = [0 0 0 1 0]x0, [1 0 1 1 0] [0 0 0 0 0] [w](x0) = [0 1 1 1 1]x0 [0 0 0 0 0] [0 0 0 1 0] , [0 0 0 0 0] [0] [0 1 1 1 1] [0] [v](x0) = [0 0 0 0 1]x0 + [0] [0 0 0 0 1] [1] [1 1 1 1 0] [0], [1 1 0 1 1] [1] [0 0 0 0 0] [0] [u](x0) = [0 1 1 0 1]x0 + [0] [1 1 0 1 1] [1] [1 1 1 0 1] [0], [1 0 0 0 0] [0] [0 1 1 0 1] [1] [c](x0) = [0 0 1 0 0]x0 + [0] [0 0 1 0 0] [0] [0 0 1 0 0] [0], [1 0 0 0 0] [1] [0 0 0 1 0] [0] [a](x0) = [0 0 1 0 0]x0 + [0] [0 0 0 1 0] [0] [0 0 0 0 1] [0], [0 0 0 0 1] [0] [0 1 0 0 0] [0] [b](x0) = [0 0 0 0 1]x0 + [0] [0 0 1 1 1] [1] [0 0 1 0 0] [0] orientation: a#(b(x)) = [0 0 1 1 1]x + [1] >= [0 0 0 1 0]x = a#(x) a#(b(x)) = [0 0 1 1 1]x + [1] >= [0 0 0 1 0]x = a#(a(x)) a#(b(x)) = [0 0 1 1 1]x + [1] >= [0 0 0 1 1]x = b#(a(a(x))) b#(c(x)) = [0 1 2 0 1]x + [1] >= [0 1 0 0 1]x = b#(x) b#(c(x)) = [0 1 2 0 1]x + [1] >= [0 1 1 0 0]x = b#(b(x)) b#(c(x)) = [0 1 2 0 1]x + [1] >= [0 0 2 0 0]x = c#(b(b(x))) c#(a(x)) = [1 0 1 0 0]x + [1] >= [1 0 1 0 0]x = c#(x) c#(a(x)) = [1 0 1 0 0]x + [1] >= [1 0 1 0 0]x = c#(c(x)) c#(a(x)) = [1 0 1 0 0]x + [1] >= [0 0 1 0 0]x = a#(c(c(x))) [0 0 0 0 1] [1] [0 0 0 0 1] [0] [0 0 1 1 1] [1] [0 0 0 1 0] [0] a(b(x)) = [0 0 0 0 1]x + [0] >= [0 0 0 0 1]x + [0] = b(a(a(x))) [0 0 1 1 1] [1] [0 0 1 1 1] [1] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [1 1 0 1 1] [2] [1 1 0 1 1] [1] a(u(x)) = [0 1 1 0 1]x + [0] >= x = x [1 1 0 1 1] [1] [1 1 1 0 1] [0] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [0 1 1 0 1] [1] [0 1 1 0 1] [1] b(c(x)) = [0 0 1 0 0]x + [0] >= [0 0 1 0 0]x + [0] = c(b(b(x))) [0 0 3 0 0] [1] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [1 1 1 1 0] [0] [0 1 1 1 1] [0] b(v(x)) = [1 1 1 1 0]x + [0] >= x = x [1 1 1 1 2] [2] [0 0 0 0 1] [0] [1 0 0 0 0] [1] [1 0 0 0 0] [1] [0 0 1 1 1] [1] [0 0 1 0 0] [0] c(a(x)) = [0 0 1 0 0]x + [0] >= [0 0 1 0 0]x + [0] = a(c(c(x))) [0 0 1 0 0] [0] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [0 0 1 0 0] [0] [1 0 1 1 0] [0] [0 1 1 2 1] [1] c(w(x)) = [0 1 1 1 1]x + [0] >= x = x [0 1 1 1 1] [0] [0 1 1 1 1] [0] problem: DPs: TRS: a(b(x)) -> b(a(a(x))) a(u(x)) -> x b(c(x)) -> c(b(b(x))) b(v(x)) -> x c(a(x)) -> a(c(c(x))) c(w(x)) -> x Qed