Opened 9 months ago

Last modified 6 weeks ago

#31800 new enhancement

CombinatorialPolyhedron indexed by non-minimal H-representations

Reported by: mkoeppe Owned by:
Priority: major Milestone: sage-9.6
Component: geometry Keywords:
Cc: gh-kliem, yzh Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: u/mkoeppe/combinatorialpolyhedron_indexed_by_non_minimal_h_representations (Commits, GitHub, GitLab) Commit: 2105731534f0b4de12410d0d8b6a009feb449ff9
Dependencies: Stopgaps:

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Given a (not necessarily minimal) H-representation, for example as a list, and a polyhedron, construct a CombinatorialPolyhedron that uses the given H-representation objects (or indices of the list) instead of the polyhedron's minimal H-representation objects.

Change History (8)

comment:1 Changed 8 months ago by mkoeppe

I think actually I only need versions of incidence_matrix (and maybe slack_matrix) that allow using some given lists of Vreps and Hreps instead of the minimal representations.

comment:2 Changed 8 months ago by gh-kliem

Basically, you want almost something as face_as_combinatorial_polyhedron from #30469.

(Slack matrix is basically the same as incidence matrix and should use the code from Polyhedron_base.incidence_matrix to do the conversion.

Given an incidence matrix, you want to delete all rows and columns of all-ones (maybe, that is a problem with lines though and with cones). Then you want to remove all non-maximal "facets" and all non-minimal "vertices". Finally we need to know how the new labels correspond to the old labels.

Did I get that right?

comment:3 Changed 8 months ago by mkoeppe

Yes, this sounds about right

comment:4 Changed 8 months ago by mkoeppe

  • Branch set to u/mkoeppe/combinatorialpolyhedron_indexed_by_non_minimal_h_representations

comment:5 Changed 8 months ago by mkoeppe

  • Commit set to 2105731534f0b4de12410d0d8b6a009feb449ff9

Here's a draft of the interface that I would find useful

New commits:

2105731Polyhedron_base.{incidence_matrix,slack_matrix,combinatorial_polyhedron}: Extend interface

comment:6 Changed 8 months ago by gh-kliem

What I get from this is the following:

Let F be the meet of the given facets and G be the join of the given vertices. Obtain the interval [F, G] as combinatorial polyhedron (with specified order of Vrep and Hrep).

Is this what you had in mind?

comment:7 Changed 6 months ago by mkoeppe

  • Milestone changed from sage-9.4 to sage-9.5

comment:8 Changed 6 weeks ago by mkoeppe

  • Milestone changed from sage-9.5 to sage-9.6
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