YES Problem: *(i(x),x) -> 1() *(1(),y) -> y *(x,0()) -> 0() *(*(x,y),z) -> *(x,*(y,z)) Proof: Polynomial Interpretation Processor: dimension: 1 interpretation: [0] = 0, [1] = 0, [*](x0, x1) = 5x0 + x1 + 1, [i](x0) = 4x0 orientation: *(i(x),x) = 21x + 1 >= 0 = 1() *(1(),y) = y + 1 >= y = y *(x,0()) = 5x + 1 >= 0 = 0() *(*(x,y),z) = 25x + 5y + z + 6 >= 5x + 5y + z + 2 = *(x,*(y,z)) problem: Qed