Move vertex facet graph to combinatorial polyhedron

[kliem]

We move the method vertex_facet_graph from Polyhedron_base to CombinatorialPolyhedron.

Along the way we fix an bug, namely that vertex_facet_graph(labels=False) has the edges the wrong way::

sage: P = polytopes.cube()
sage: P.vertex_facet_graph().is_isomorphic(P.vertex_facet_graph(False))
False
sage: P.vertex_facet_graph().is_isomorphic(P.vertex_facet_graph(False).reverse())
True

CC: @jplab @LaisRast

Component: geometry

Keywords: polyhedra, vertex facet graph, combinatorial polyhedron

Author: Jonathan Kliem

Branch/Commit: a36a211

Reviewer: Jean-Philippe Labbé

Issue created by migration from https://trac.sagemath.org/ticket/29188

[kliem]

New commits:

630b8a8	add vertex_facet_graph to combinatorial polyhedron
6dbf267	use combinatorial polyhedron to obtain the vertex facet graph

[kliem]

Branch: public/29188

[kliem]

Commit: 6dbf267

[jplab]

Reviewer: Jean-Philippe Labbé

[jplab]

comment:2

There is a space missing in the inputs.

Then, I would just swap the two examples to show the default behavior first.

Could you make this sentence more clear:

If ``names`` is ``True`` but no names are provided,

I would suggest to put If names is True (the default) but no names....

[kliem]

New commits:

9a62a52	add vertex_facet_graph to combinatorial polyhedron
1e10ebd	use combinatorial polyhedron to obtain the vertex facet graph
7bae9dc	improved doc

[kliem]

Changed branch from public/29188 to public/29188-reb

[kliem]

Changed commit from 6dbf267 to 7bae9dc