D.7.1.13 shortid

Procedure from library presolve.lib (see presolve_lib).

Usage:

shortid(id,n[,e]); id= ideal/module, n,e=integers

Return:

- if called with two arguments or e=0:
same type as id, containing generators of id having <= n terms.
- if called with three arguments and e!=0:
a list L:
L[1]: same type as id, containing generators of id having <= n terms.
L[2]: number of corresponding generator of id

Note:

May be used to compute partial standard basis in case id is to hard

Example:

LIB "presolve.lib";
ring s=0,(x,y,z,w),dp;
ideal i = (x3+y2+yw2)^2,(xz+z2)^2,xyz-w2-xzw; 
shortid(i,3);
→ _[1]=x2z2+2xz3+z4
→ _[2]=xyz-xzw-w2