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D.6.6.3 esStratum
Procedure from library equising.lib (see equising_lib).
- Usage:
- esStratum(F[,m,L]); F poly, m int, L list
- Assume:
- F defines a deformation of a reduced bivariate polynomial f
and the characteristic of the basering does not divide mult(f).
If nv is the number of variables of the basering, then the first
nv-2 variables are the deformation parameters.
If the basering is a qring, ideal(basering) must only depend
on the deformation parameters.
- Compute:
- equations for the stratum of equisingular deformations with
fixed (trivial) section.
- Return:
- list l: either consisting of a list and an integer, where
| l[1][1]=ideal defining the equisingularity stratum
l[1][2]=ideal defining the part of the equisingularity stratum where all
equimultiple sections through the non-nodes of the reduced total
transform are trivial sections
l[2]=1 if some error has occured, l[2]=0 otherwise;
| or consisting of a ring and an integer, where
| l[1]=ESSring is a ring extension of basering containing the ideal ES
(describing the ES-stratum), the ideal ES_all_triv (describing the
part with trival equimultiple sections) and the polynomial p_F=F,
l[2]=1 if some error has occured, l[2]=0 otherwise.
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- Note:
- L is supposed to be the output of hnexpansion (with the given ordering
of the variables appearing in f).
If m is given, the ES Stratum over A/maxideal(m) is computed.
This procedure uses execute or calls a procedure using
execute .
printlevel>=2 displays additional information.
Example:
See also:
esIdeal;
isEquising.
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