For subschemes X,Y of ℙn1x...xℙnm this command computes the Segre class s(X,Y) of X in Y as a class in the Chow ring of ℙn1x...xℙnm.
i1 : R = makeProductRing({3,3}) o1 = R o1 : PolynomialRing |
i2 : x = gens(R) o2 = {a, b, c, d, e, f, g, h} o2 : List |
i3 : D = minors(2,matrix{{x_0..x_3},{x_4..x_7}}) o3 = ideal (- b*e + a*f, - c*e + a*g, - c*f + b*g, - d*e + a*h, - d*f + b*h, ------------------------------------------------------------------------ - d*g + c*h) o3 : Ideal of R |
i4 : X = ideal(x_0*x_1,x_1*x_2,x_0*x_2) o4 = ideal (a*b, b*c, a*c) o4 : Ideal of R |
i5 : segre(X,D) 3 3 3 2 2 3 o5 = - 10H H + 3H H + 3H H 1 2 1 2 1 2 ZZ[H , H ] 1 2 o5 : ---------- 4 4 (H , H ) 1 2 |
i6 : A = makeChowRing(R) o6 = A o6 : QuotientRing |
i7 : s = segre(X,D,A) 3 3 3 2 2 3 o7 = - 10H H + 3H H + 3H H 1 2 1 2 1 2 o7 : A |