#10140: Base sage.geometry.cone on the Parma Polyhedra Library (PPL)
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Reporter: vbraun | Owner: mhampton
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-4.7
Component: geometry | Keywords: ppl
Author: Volker Braun | Upstream: N/A
Reviewer: Andrey Novoseltsev | Merged:
Work_issues: |
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Comment(by vbraun):
Since the faces of `P` and `(2*P).polar()` have no particular relationship
I see it as a feature that we don't pretend otherwise. In the worst case
you have to separately construct the face lattice of `2*P`. Is it really
that time-critical? Why can't you just work with `P` alone in that case?
The underlying implementation may very well rely on some ray order, this
is why we have the `check=False` option. Just make sure that it is exposed
by some reasonable class/method hierarchy, and make sure to spell out
that the underlying implementation is subject to change and everyone has
to go through the `dual_face()` method or whatever it is called.
Its funny that you mention the ideals, because they make no promise about
the generators. The `MPolynomialIdeal` class tries to abstract the
mathematical notion of ideal, there is no particular choice of generators
implied (and any particular choice is subject to change without notice).
This is why methods like `ideal.groebner_basis()` return a
`PolynomialSequence` and not a `MPolynomialIdeal`.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10140#comment:34>
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