D.5.5.12 stripHNE

Procedure from library hnoether.lib (see hnoether_lib).

Usage:

stripHNE(L); L list

Assume:

L is 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:

list in the same format as L, but all polynomials L[4], resp. L[i][4], are set to zero.

Note:

The purpose of this procedure is to remove huge amounts of data no longer needed. It is useful, if one or more of the polynomials in L consume much memory. It is still possible to compute invariants, parametrizations etc. with the stripped HNE(s), but it is not possible to use extdevelop with them.

Example:

LIB "hnoether.lib";
ring r=0,(x,y),dp;
list hne=develop(x2+y3+y4);
hne;
→ [1]:
→    _[1,1]=0
→    _[1,2]=x
→    _[2,1]=0
→    _[2,2]=-1
→ [2]:
→    1,-1
→ [3]:
→    1
→ [4]:
→    x4-2x2y+y2+y
→ [5]:
→    1
stripHNE(hne);
→ [1]:
→    _[1,1]=0
→    _[1,2]=x
→    _[2,1]=0
→    _[2,2]=-1
→ [2]:
→    1,-1
→ [3]:
→    1
→ [4]:
→    0
→ [5]:
→    1

See also: develop; extdevelop; hnexpansion.