YES(?,O(n^2)) Problem: norm(nil()) -> 0() norm(g(x,y)) -> s(norm(x)) f(x,nil()) -> g(nil(),x) f(x,g(y,z)) -> g(f(x,y),z) rem(nil(),y) -> nil() rem(g(x,y),0()) -> g(x,y) rem(g(x,y),s(z)) -> rem(x,z) Proof: Matrix Interpretation Processor: dimension: 2 interpretation: [1 4] [1 1] [0] [rem](x0, x1) = [0 1]x0 + [0 0]x1 + [5], [1 14] [1 2] [1 ] [f](x0, x1) = [0 0 ]x0 + [0 1]x1 + [10], [1 8] [1] [s](x0) = [0 0]x0 + [1], [1 10] [0] [g](x0, x1) = x0 + [0 0 ]x1 + [4], [7] [0] = [1], [1 4] [0] [norm](x0) = [0 0]x0 + [1], [0] [nil] = [7] orientation: [28] [7] norm(nil()) = [1 ] >= [1] = 0() [1 4] [1 10] [16] [1 4] [9] norm(g(x,y)) = [0 0]x + [0 0 ]y + [1 ] >= [0 0]x + [1] = s(norm(x)) [1 14] [15] [1 10] [0 ] f(x,nil()) = [0 0 ]x + [17] >= [0 0 ]x + [11] = g(nil(),x) [1 14] [1 2] [1 10] [9 ] [1 14] [1 2] [1 10] [1 ] f(x,g(y,z)) = [0 0 ]x + [0 1]y + [0 0 ]z + [14] >= [0 0 ]x + [0 1]y + [0 0 ]z + [14] = g(f(x,y),z) [1 1] [28] [0] rem(nil(),y) = [0 0]y + [12] >= [7] = nil() [1 4] [1 10] [24] [1 10] [0] rem(g(x,y),0()) = [0 1]x + [0 0 ]y + [9 ] >= x + [0 0 ]y + [4] = g(x,y) [1 4] [1 10] [1 8] [18] [1 4] [1 1] [0] rem(g(x,y),s(z)) = [0 1]x + [0 0 ]y + [0 0]z + [9 ] >= [0 1]x + [0 0]z + [5] = rem(x,z) problem: Qed