Outline

Overview

Ext

Primdec

Normalize

MuPAD

Deform

Classify

Puiseux

Future

Equidimensional Part


Calculate the equidimensional part of a variety via Ext-groups.

The equidimensional part of V={xz=yz=0} is given by the ideal:

(z)=ann(Ext1(K[x,y,z]/(xz,yz),K[x,y,z]))

LIB "homolog.lib";
ring r=0,(x,y,z),dp;
ideal i=xz,yz;
module m=Ext_R(1,i);
quotient(m,freemodule(nrows(m)));
=> _[1]=z

Ext - anihilator

ICM'98 http://www.mathematik.uni-kl.de/~zca/Singular