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A protection against removing valuable polynomial equations
is to not use the fact that the polynomial equations
from a few categories may imply equations from a
different category. This includes the case when two
equations involving unknowns yield an equation
involving only knowns. Certainly, if NCProcess
finds an equation involving
knowns, then this equation should be retained.
Recall that a spreadsheet
consists of
- (1) Polynomial equations which solve for a variable.
- (2) Polynomial equations which do not involve any unknowns.
- (3) User selected and user created polynomial equations.
- (4) Undigested polynomials.
The equations in (1), (2) and (3) above were referred to
as digested equations. These items were displayed in
terms of a list of smaller sets of equations called
categories.
This division of a set of polynomial equations into categories
suggests the following possible ways to shrink a set of
polynomial equations
while preserving important equations.
- I.
Let be the categories.
The simplest way is to replace
with a minimal set
such that the 's and the 's generate the same ideal.
- II. The most drastic
way to shrink
is to
pick an ordering
on categories of undigested
polynomial equations
(for example, the one induced by the
ordering underlying the run) and
output the subset and
defined to satisfy
- (1) A minimal generating set for the digested
polynomials D. Call it .
- (2) A minimal set of the form
which is a generating set for the ideal generated by
the union of the digested polynomials D and the category .
- (3) A minimal set of the form
which is a generating set for the ideal generated by
the union of the digested polynomial D and the categories and .
- (4) etc.
Here D is the set of digested polynomials.
- III. An intermediate course which
is less sensitive to ordering is
to output the subset and
defined to satisfy
- (1)
A minimal generating set for the digested
polynomials D. Call it .
- (2)
A minimal set of the form
which is a generating set for the ideal generated by
the union of the digested polynomials D and the category .
- (3)
A minimal set of the form
which is a generating set for the ideal generated by
the union of the digested polynomials D and the category .
- (4) etc.
Here D is the set of digested polynomials.
Next: Practical shrinking by category
Up: Respect for categories
Previous: Respect for categories
Helton
Wed Jul 3 10:27:42 PDT 1996