curveOnScroll -- Computes the ideal of a canonical curve on a normalized scroll in terms of generators of the scroll

• Usage:

  J=curveOnScroll(Ican,g,k)

• Inputs:
  • Ican, an ideal, the ideal of a genus g canonical curve with a degree k line bundle on a normalized scroll
  • g, an integer, the genus
  • k, an integer, the degree of the line bundle on C
• Outputs:
  • Jcan, an ideal, the ideal of the canonical curve in terms of generators of the scroll

i1 : (g,k,n) = (8,5,1000);

i2 : Ican = canCurveWithFixedScroll(g,k,n);

               ZZ
o2 : Ideal of ----[t ..t ]
              1009  0   7

i3 : Jcan = curveOnScroll(Ican,g,k);

               ZZ
o3 : Ideal of ----[pp ..pp , v..w]
              1009   0    3

i4 : betti Jcan

            0 1
o4 = total: 1 5
         0: 1 .
         1: . .
         2: . 4
         3: . 1

o4 : BettiTally