YES(?,O(n^3)) Problem: c(b(a(X))) -> a(a(b(b(c(c(X)))))) a(X) -> e() b(X) -> e() c(X) -> e() Proof: Complexity Transformation Processor: strict: c(b(a(X))) -> a(a(b(b(c(c(X)))))) a(X) -> e() b(X) -> e() c(X) -> e() weak: Matrix Interpretation Processor: dimension: 1 max_matrix: 1 interpretation: [e] = 0, [c](x0) = x0, [b](x0) = x0 + 1, [a](x0) = x0 orientation: c(b(a(X))) = X + 1 >= X + 2 = a(a(b(b(c(c(X)))))) a(X) = X >= 0 = e() b(X) = X + 1 >= 0 = e() c(X) = X >= 0 = e() problem: strict: c(b(a(X))) -> a(a(b(b(c(c(X)))))) a(X) -> e() c(X) -> e() weak: b(X) -> e() Matrix Interpretation Processor: dimension: 1 max_matrix: 1 interpretation: [e] = 0, [c](x0) = x0, [b](x0) = x0, [a](x0) = x0 + 1 orientation: c(b(a(X))) = X + 1 >= X + 2 = a(a(b(b(c(c(X)))))) a(X) = X + 1 >= 0 = e() c(X) = X >= 0 = e() b(X) = X >= 0 = e() problem: strict: c(b(a(X))) -> a(a(b(b(c(c(X)))))) c(X) -> e() weak: a(X) -> e() b(X) -> e() Matrix Interpretation Processor: dimension: 1 max_matrix: 1 interpretation: [e] = 0, [c](x0) = x0 + 1, [b](x0) = x0, [a](x0) = x0 orientation: c(b(a(X))) = X + 1 >= X + 2 = a(a(b(b(c(c(X)))))) c(X) = X + 1 >= 0 = e() a(X) = X >= 0 = e() b(X) = X >= 0 = e() problem: strict: c(b(a(X))) -> a(a(b(b(c(c(X)))))) weak: c(X) -> e() a(X) -> e() b(X) -> e() Matrix Interpretation Processor: dimension: 3 max_matrix: [1 1 1] [0 0 1] [0 0 0] interpretation: [0] [e] = [0] [0], [1 0 1] [1] [c](x0) = [0 0 1]x0 + [0] [0 0 0] [0], [1 1 0] [0] [b](x0) = [0 0 0]x0 + [0] [0 0 0] [1], [1 0 0] [0] [a](x0) = [0 0 1]x0 + [1] [0 0 0] [0] orientation: [1 0 1] [3] [1 0 1] [2] c(b(a(X))) = [0 0 0]X + [1] >= [0 0 0]X + [1] = a(a(b(b(c(c(X)))))) [0 0 0] [0] [0 0 0] [0] [1 0 1] [1] [0] c(X) = [0 0 1]X + [0] >= [0] = e() [0 0 0] [0] [0] [1 0 0] [0] [0] a(X) = [0 0 1]X + [1] >= [0] = e() [0 0 0] [0] [0] [1 1 0] [0] [0] b(X) = [0 0 0]X + [0] >= [0] = e() [0 0 0] [1] [0] problem: strict: weak: c(b(a(X))) -> a(a(b(b(c(c(X)))))) c(X) -> e() a(X) -> e() b(X) -> e() Qed