ff [v1 w1 v2 w2 ... vm wm] ord_w d poly ff; string v1; integer w1; ... order of the initial of ff by the weight vector [w1 w2 ...] Example: [(x,y) ring_of_polynomials 0] define_ring (x^2 y^3-x). [(x) 2 (y) 1] ord_w ::