YES(?,O(n^2)) Problem: +(*(x,y),*(a(),y)) -> *(+(x,a()),y) *(*(x,y),z) -> *(x,*(y,z)) Proof: RT Transformation Processor: strict: +(*(x,y),*(a(),y)) -> *(+(x,a()),y) *(*(x,y),z) -> *(x,*(y,z)) weak: Matrix Interpretation Processor: dimension: 1 interpretation: [+](x0, x1) = x0 + x1 + 3, [a] = 14, [*](x0, x1) = x0 + x1 + 4 orientation: +(*(x,y),*(a(),y)) = x + 2y + 25 >= x + y + 21 = *(+(x,a()),y) *(*(x,y),z) = x + y + z + 8 >= x + y + z + 8 = *(x,*(y,z)) problem: strict: *(*(x,y),z) -> *(x,*(y,z)) weak: +(*(x,y),*(a(),y)) -> *(+(x,a()),y) Matrix Interpretation Processor: dimension: 2 interpretation: [1 1] [4] [+](x0, x1) = [0 0]x0 + x1 + [2], [14] [a] = [1 ], [1 2] [0] [*](x0, x1) = [0 1]x0 + x1 + [8] orientation: [1 4] [1 2] [16] [1 2] [1 2] [0 ] *(*(x,y),z) = [0 1]x + [0 1]y + z + [16] >= [0 1]x + [0 1]y + z + [16] = *(x,*(y,z)) [1 3] [2 1] [28] [1 1] [24] +(*(x,y),*(a(),y)) = [0 0]x + [0 1]y + [11] >= [0 0]x + y + [11] = *(+(x,a()),y) problem: strict: weak: *(*(x,y),z) -> *(x,*(y,z)) +(*(x,y),*(a(),y)) -> *(+(x,a()),y) Qed