#18860: Faster Poyhedron.graph()
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Reporter: | Owner:
ncohen | Status: needs_review
Type: | Milestone: sage-6.8
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
geometry | Work issues:
Keywords: | Commit:
Authors: | 74d8412010748142918edf6178636bffdb14e60a
Nathann Cohen | Stopgaps:
Report Upstream: N/A |
Branch: |
public/18860 |
Dependencies: |
#18779 |
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Comment (by dimpase):
Replying to [comment:10 ncohen]:
> Here is a new 'combinatorial' version. It uses an 'idea', which I am not
sure is a proper definition of the object, but well... You tell me `:-P`
>
> 1) For every inequality `I`, build the set `set(I)` of points for which
it is an equality
> 2) For any pair of points `i,j`, list all inequalities `I_1, ..., I_k`
that contain them both
> 3) Intersection `set(I_1), ..., set(I_k)`. If this intersection has
cardinality 2, then ij is an edge.
yes, that's correct for the polytopes - provided there is no redundancy.
E.g. if a polytope is not full-dimensional, then adding an equation
satisfied by all the vertices to an inequality is a "copy" of this
inequality, vertex-vise.
> Works for Gosset (at least) `:-P`
>
> Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/18860#comment:19>
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