next | previous | forward | backward | up | top | index | toc | Macaulay2 web site
NumericalGodeaux :: normalBundleLineInQ

normalBundleLineInQ -- compute the normal bundle of a line in Q

Synopsis

Description

If the chosen line l does not intersect the singular locus of the complete intersection Q, the the normal sheaf Nl|Q is locally free, hence isomorphic to a line bundle on 1. Note that if h1(Nl|Q) = 0, then the Fano scheme of lines in Q is smooth at the corresponding point.

i1 : kk = ZZ/nextPrime(32001);
i2 : s = "1111";
i3 : (relLin,relPfaf,d1',d2,Ms) = setupGodeaux(kk,s);
i4 : (randLine,subsLine) = randomLineTorsZ5(d1',relPfaf);
i5 : normalBundle = normalBundleLineInQ(subsLine,relPfaf)

                       2                         4
o5 = OO                 (1) ++ OO
       Proj(kk[x , x ])          Proj(kk[x , x ])
                0   1                     0   1

o5 : coherent sheaf on Proj(kk[x , x ]), free
                                0   1
i6 : HH^1(normalBundle)

o6 = 0

o6 : kk-module

Caveat

We do not check whether the line intersects the singular locus or not.

Ways to use normalBundleLineInQ :