-- -*- M2-comint -*- {* hash: -1743911704 *} i1 : R = ZZ[a]/(a^2-3)[x,y] o1 = R o1 : PolynomialRing i2 : F = y^2-x*(x-1)*(x-a) 3 2 2 o2 = - x + (a + 1)x + y - a*x o2 : R i3 : J = ideal(diff(x,F),diff(y,F),F) 2 3 2 2 o3 = ideal (- 3x + (2a + 2)x - a, 2y, - x + (a + 1)x + y - a*x) o3 : Ideal of R i4 : gens gb J o4 = | 12 6a+6 2y 4x-2a+6 2xa+2x+2a+6 y2+2x-a-3 x2+3a | 1 7 o4 : Matrix R <--- R i5 : peek J.generators.cache o5 = CacheTable{GroebnerBasisOptions{HardDegreeLimit => null} => GroebnerBasis[status: done; S-pairs encountered up to degree 5]} Syzygies => false SyzygyRows => 0 image => image | -3x2+2xa+2x-a 2y -x3+x2a+x2+y2-xa | isHomogeneous => false i6 : gbRemove J i7 : peek J.generators.cache o7 = CacheTable{image => image | -3x2+2xa+2x-a 2y -x3+x2a+x2+y2-xa |} isHomogeneous => false i8 :