D.5.5.11 intersection

Procedure from library hnoether.lib (see hnoether_lib).

Usage:

intersection(hne1,hne2); hne1, hne2 lists

Assume:

hne1, hne2 represent a HNE (i.e., are the output of develop(f), or of extdevelop(develop(f),n), or one entry of the list hne in the ring created by hnexpansion(f[,"ess"])).

Return:

int, the intersection multiplicity of the branches corresponding to hne1 and hne2.

Example:

LIB "hnoether.lib";
// ------ the example starts here -------
ring r=0,(x,y),dp;
list hn=hnexpansion((x2-y3)*(x2+y3));
def HNEring=hn[1];
setring HNEring;
intersection(hne[1],hne[2]);
→ 6

See also: displayInvariants; hnexpansion.