#13202: conversion problems in BooleanPolynomialRing with degrevlex order
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Reporter: Bouillaguet | Owner: malb
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-5.2
Component: commutative algebra | Resolution:
Keywords: conversion | Work issues:
Report Upstream: N/A | Reviewers:
Martin Albrecht
Authors: Alexander Dreyer, Charles Bouillaguet | Merged in:
Dependencies: | Stopgaps:
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Comment (by AlexanderDreyer):
Replying to [comment:15 Bouillaguet]:
> So, I don't exactly understand what the plan is. The patch, even though
it fixes the problem at the origin of this ticket, does not fixes all
problems:
>
> - m.index() exposes the hack behind the current implementation of
degreglex
Yes, I'm about to fix that. (It's not only index to be fixed.)
> - Alexander seems to believe that there is a problem with variables()
I thought ring.variable(i) should give the i-th polybori variable (not
reordered). But thinking twice, that would cause more problems than it
solves.
> So, do we want to remove the degrevlex from BooleanPolynomialRing
altogether, and instruct users to use the newly implemented degneglex
instead, or do we want to actually support degrevlex? (and how?)
The problem is the ambigious nature of pbori.pyx:
On the one hand, it is the Sage implementation of BooleanPolynomial which
should support degrevlex in such a way, that the user is not aware of the
reversed variables hack.
On the other hand, Sage uses pbori.pyx as a lightweight alternative to
polybori's original (boost-based) C++-to-python interface (for running
polybori's highlevel library stuff in <python-site>/polybori/*). We don't
need degrevlex here (but degneglex).
The latter is trivial, once `DegNegLex` is in Sage. For the first point, I
will provide a first variant later this day.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13202#comment:16>
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