#28626 closed enhancement (fixed)
Compute graph of polyhedron with CombinatorialPolyhedron
Reported by: | gh-kliem | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-9.1 |
Component: | geometry | Keywords: | polyhedron, combinatorial_polyhedron |
Cc: | jipilab, gh-LaisRast | Merged in: | |
Authors: | Jonathan Kliem | Reviewers: | Dima Pasechnik, Jean-Philippe Labbé |
Report Upstream: | N/A | Work issues: | |
Branch: | 01d1907 (Commits, GitHub, GitLab) | Commit: | 01d1907cd51b34a3e5b454897efbe0f5d2a61a75 |
Dependencies: | #28621, #28603 | Stopgaps: |
Description (last modified by )
We use CombinatorialPolyhedron
to compute the graph of Polyhedron_base
.
In the case of polyhedra with lines
aka unpointed polyhedra this changes the behavior:
- Old behavior: The vertex graph basically ignored the lines, so that
sage: P = Polyhedron(vertices=my_vertices, rays=my_rays, lines=my_lines) sage: Q = Polyhedron(vertices=my_vertices, rays=my_rays)
have the same graph (assuming the Vrepresentation as['my_vertices', 'my_rays', 'my_lines']
is minimal). - New behavior: The vertex graph of a polyhedron with lines contains no vertices as the polyhedron as no vertices.
We add information about this to the documentation of vertex_graph
.
We alter a doctest in combinatorial_automorphism_group
that assumed the old behavior.
See https://groups.google.com/d/msg/sage-devel/lTwb_P0nBEw/_R4vXOxgDAAJ for the discussion of this change.
Change History (22)
comment:1 Changed 18 months ago by
- Dependencies changed from #28621 to #28621, #28603
comment:2 Changed 18 months ago by
- Branch set to public/28626
- Cc jipilab gh-LaisRast added
- Commit set to fe0978473dab16ee78ebbc52ac87b6cfb3649ee1
- Keywords polyhedron combinatorial_polyhedron added
comment:3 Changed 18 months ago by
it is not clear from the ticket description why edge_graph is deprecated, can you explain?
comment:4 Changed 18 months ago by
Sorry about the confusion. This ticket is built on top of #28603 and #28621. Only the last commit is due to this ticket.
In CombinatorialPolyhedron
, I chose to implement a method edge_graph
. In order to make it more compatible with Polyhedron
I replace it by vertex_graph
in #28603.
This way CombinatorialPolyhedron(P).vertex_graph()
gives the vertex graph of our polyhedron P
.
There are two issues with edge graph:
- It has no vertices if there are no edges (a 0-dimensional polyhedron).
- It depends not just on the combinatorial type, for example those two
sage: Q = Polyhedron(vertices=[[1,0],[0,1]],rays=[[1,11/10],[11/10,1]]); Q A 2-dimensional polyhedron in QQ^2 defined as the convex hull of 2 vertices and 2 rays sage: P = Polyhedron(vertices=[[1,0],[0,1]],rays=[[1,1]]); P A 2-dimensional polyhedron in QQ^2 defined as the convex hull of 2 vertices and 1 ray
polyhedra do not have isomorphicedge_graph
s inCombinatorialPolyhedron
.
comment:5 Changed 18 months ago by
So this does bring the sanity in, where vertices correspond to vertices in the geometric sense, right?
comment:6 follow-up: ↓ 17 Changed 18 months ago by
Yes.
However, as I'm changing the behavior, I didn't want to do it secretely and see if there are objections. Hence the post on sage_devel.
comment:7 Changed 18 months ago by
- Reviewers set to Dima Pasechnik
Are you still working on the ticket, or it needs review?
comment:8 Changed 18 months ago by
I mostly waited, if there where objections to changing the behavior.
If there are none, I need to change the failing test and probably comment on the vertices being different from the method vertices
.
comment:9 Changed 18 months ago by
- Description modified (diff)
comment:10 Changed 18 months ago by
- Commit changed from fe0978473dab16ee78ebbc52ac87b6cfb3649ee1 to 01d1907cd51b34a3e5b454897efbe0f5d2a61a75
comment:11 Changed 18 months ago by
- Status changed from new to needs_review
comment:12 Changed 15 months ago by
- Milestone changed from sage-9.0 to sage-9.1
Ticket retargeted after milestone closed
comment:13 Changed 15 months ago by
Is this ticket good to go?
comment:14 follow-up: ↓ 15 Changed 15 months ago by
How about the bot report:
========== pyflakes ========== git checkout patchbot/ticket_merged src/sage/geometry/polyhedron/base.py:5189: local variable 'ambient_dim' is assigned to but never used src/sage/geometry/polyhedron/base.py:5190: local variable 'polytope_dim' is assigned to but never used
comment:15 in reply to: ↑ 14 Changed 15 months ago by
Replying to dimpase:
How about the bot report:
========== pyflakes ========== git checkout patchbot/ticket_merged src/sage/geometry/polyhedron/base.py:5189: local variable 'ambient_dim' is assigned to but never used src/sage/geometry/polyhedron/base.py:5190: local variable 'polytope_dim' is assigned to but never used
Fixed in #28880.
comment:16 Changed 12 months ago by
- Milestone changed from sage-9.1 to sage-9.2
Batch modifying tickets that will likely not be ready for 9.1, based on a review of the ticket title, branch/review status, and last modification date.
comment:17 in reply to: ↑ 6 Changed 12 months ago by
- Reviewers changed from Dima Pasechnik to Dima Pasechnik, Jean-Philippe Labbé
- Status changed from needs_review to needs_info
Replying to gh-kliem:
Yes.
However, as I'm changing the behavior, I didn't want to do it secretely and see if there are objections. Hence the post on sage_devel.
Could you link to the post?
I would say that the ticket looks ready, but for the sake of completeness, I would like to check the change of behavior...
comment:18 Changed 12 months ago by
- Description modified (diff)
- Status changed from needs_info to needs_review
comment:19 Changed 12 months ago by
- Status changed from needs_review to positive_review
comment:20 Changed 12 months ago by
Thank you.
comment:21 Changed 12 months ago by
- Branch changed from public/28626 to 01d1907cd51b34a3e5b454897efbe0f5d2a61a75
- Resolution set to fixed
- Status changed from positive_review to closed
comment:22 Changed 12 months ago by
- Milestone changed from sage-9.2 to sage-9.1
What do we do with polyhedra that contain lines?
As of now it is understood that in this case the vertex_graph is non-empty. So the vertex graph is basically the one of the projection.
However, the docstring of
vertex_graph
states that the edges correspond to edges of the polyhedron. I find it very confusing that thevertex_graph
of an unpointed polyhedron should have edges.If people think this is the way it should be than the docstring of
vertex_graph
should be more precise.I stumbled upon this because I got a test failure at
File "src/sage/geometry/polyhedron/base.py", line 7229
This is a weird test, as it tests a behavior which seems to be opposed to the intention of
vertex_graph
. Also the announcement is strange, as thevertex_graph
contains neither rays nor lines and thus will not interchange them (not even a ray with a ray).New commits:
added combinatorial polyhedron as an attribute for polyhedra
added vertex_graph, deprecated edge_graph
improved deprecation warning
deprecation warning gives new name
changed stacklevel to 3, so deprecation warning shows during normal usage
Merge branch 'public/28603' of git://trac.sagemath.org/sage into public/28626
calculate vertex_graph using combinatorialpolyhedron