YES Problem: b(y,z) -> f(c(c(y,z,z),a(),a())) b(b(z,y),a()) -> z c(f(z),f(c(a(),x,a())),y) -> c(f(b(x,z)),c(z,y,a()),a()) Proof: DP Processor: DPs: b#(y,z) -> c#(y,z,z) b#(y,z) -> c#(c(y,z,z),a(),a()) c#(f(z),f(c(a(),x,a())),y) -> c#(z,y,a()) c#(f(z),f(c(a(),x,a())),y) -> b#(x,z) c#(f(z),f(c(a(),x,a())),y) -> c#(f(b(x,z)),c(z,y,a()),a()) TRS: b(y,z) -> f(c(c(y,z,z),a(),a())) b(b(z,y),a()) -> z c(f(z),f(c(a(),x,a())),y) -> c(f(b(x,z)),c(z,y,a()),a()) Matrix Interpretation Processor: dim=3 usable rules: b(y,z) -> f(c(c(y,z,z),a(),a())) b(b(z,y),a()) -> z c(f(z),f(c(a(),x,a())),y) -> c(f(b(x,z)),c(z,y,a()),a()) interpretation: [c#](x0, x1, x2) = [0 2 0]x0 + [0 1 1]x1 + [0 1 1]x2, [b#](x0, x1) = [0 2 0]x0 + [0 2 2]x1 + [3], [2 0 0] [f](x0) = [0 1 1]x0 [2 0 0] , [0] [a] = [1] [0], [0 2 0] [0 1 1] [2 0 1] [c](x0, x1, x2) = [0 0 0]x0 + [0 0 0]x1 + [0 0 0]x2 [0 2 0] [0 0 1] [0 0 2] , [1 1 0] [0 0 0] [2] [b](x0, x1) = [0 1 0]x0 + [0 0 1]x1 + [0] [0 0 1] [0 0 0] [2] orientation: b#(y,z) = [0 2 0]y + [0 2 2]z + [3] >= [0 2 0]y + [0 2 2]z = c#(y,z,z) b#(y,z) = [0 2 0]y + [0 2 2]z + [3] >= [2] = c#(c(y,z,z),a(),a()) c#(f(z),f(c(a(),x,a())),y) = [0 2 3]x + [0 1 1]y + [0 2 2]z + [6] >= [0 1 1]y + [0 2 0]z + [1] = c#(z,y,a()) c#(f(z),f(c(a(),x,a())),y) = [0 2 3]x + [0 1 1]y + [0 2 2]z + [6] >= [0 2 0]x + [0 2 2]z + [3] = b#(x,z) c#(f(z),f(c(a(),x,a())),y) = [0 2 3]x + [0 1 1]y + [0 2 2]z + [6] >= [0 2 2]x + [0 0 1]y + [0 2 2]z + [5] = c#(f(b(x,z)),c(z,y,a()),a()) [1 1 0] [0 0 0] [2] [2] b(y,z) = [0 1 0]y + [0 0 1]z + [0] >= [0] = f(c(c(y,z,z),a(),a())) [0 0 1] [0 0 0] [2] [2] [0 0 1] [1 2 0] [4] b(b(z,y),a()) = [0 0 1]y + [0 1 0]z + [0] >= z = z [0 0 0] [0 0 1] [4] [0 2 3] [2 0 1] [0 2 2] [6] [0 2 2] [0 0 1] [0 2 2] [4] c(f(z),f(c(a(),x,a())),y) = [0 0 0]x + [0 0 0]y + [0 0 0]z + [0] >= [0 0 0]x + [0 0 0]y + [0 0 0]z + [0] = c(f(b(x,z)),c(z,y,a()),a()) [0 2 2] [0 0 2] [0 2 2] [4] [0 2 2] [0 0 1] [0 2 2] [4] problem: DPs: TRS: b(y,z) -> f(c(c(y,z,z),a(),a())) b(b(z,y),a()) -> z c(f(z),f(c(a(),x,a())),y) -> c(f(b(x,z)),c(z,y,a()),a()) Qed