#17474: directed graph from polyhedron
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Reporter: chapoton | Owner:
Type: enhancement | Status: needs_info
Priority: minor | Milestone: sage-6.5
Component: geometry | Resolution:
Keywords: polyhedron, | Merged in:
digraph | Reviewers:
Authors: Frédéric Chapoton | Work issues:
Report Upstream: N/A | Commit:
Branch: u/chapoton/17474 | dcf52646553cf73a3f1dff85b731a22bcc8b7ddd
Dependencies: | Stopgaps:
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Changes (by tmonteil):
* status: needs_review => needs_info
Comment:
In your implementation, there is no oriented edge associated to an edge of
the polyhedron that belongs to the kernel of the linear form, hence the
underlying undirected graph of your graph is only a subgraph of vertices
and edges of the polyhedron, see for example:
{{{
sage: penta = Polyhedron([[0,0],[1,0],[0,1],[1,2],[3,2]])
sage: penta.vertex_digraph(vector([1,0]))
}}}
What is the purpose of this method ? Depending on this, the described
behaviour may cause troubles. Other possibilities is to have two oriented
edges facing eachother (just replace `> 0` by `>= 0`), or choosing one
(but you lose some symmetry).
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Ticket URL: <http://trac.sagemath.org/ticket/17474#comment:6>
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