D.5.2.60 EulerAff

Usage:

EulerAff(I); I an ideal

Return:

integer

Purpose:

computes the Euler characteristic of the affine variety defined by I

Note:

LIB "chern.lib";
ring r = 0, (x, y), dp;
// compute the Euler characteristic of the affine elliptic curve y^2=x^3+x+1;
ideal I=y2-x3-x-1;
EulerAff(I);
==> -1