#8987: Add support for rational polyhedral fans
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Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.4.4
Component: geometry | Keywords:
Author: Andrey Novoseltsev | Upstream: N/A
Reviewer: Volker Braun | Merged:
Work_issues: |
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Comment(by novoselt):
The work is going, however I am a bit concerned about face lattices of
cones. As written above, for `Cone_of_fan` objects it should consist of
other `Cone_of_fan`s, which know their position in the fan, but not really
in the cone from which they were obtained. I think this makes perfect
sense, will be convenient, fast, and compact in memory.
However for plain `Cone`s faces are `ConeFace` objects that know how they
are related to the original cone. This means that if someone just has some
`cone` such that `is_Cone(cone)==True`, the result of `face_lattice` and
its object is undetermined. Things are especially unpleasant for
incomplete fans, since computing their `cone_lattice` relies on computing
`face_lattice`s of generating cones...
What are your thoughts on this subject? A sort of simple solution is to
hide computing faces of plain cones and only allow it for fans. (If one
wants to get faces of a single cone - we can construct a fan from this
cone and deal with its lattice...) Or we can just ignore it and hope that
users know what they are doing ;-)
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8987#comment:21>
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