#13638: fix adjacency of rays
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Reporter: vbraun | Owner: mhampton
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.5
Component: geometry | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Volker Braun | Merged in:
Dependencies: | Stopgaps:
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Comment (by dimpase):
Replying to [comment:5 vbraun]:
> How about:
>
> If the V-representation of the polygon contains only vertices and a
single ray, then every V-representation object has exact two adjacent
ones. The cyclic order is unique up to reversal of direction and choice of
starting point.
>
> If the V-representation of the polygon contains vertices and two rays,
then the two rays are not adjacent to each other. The cyclic order then
starts with one of the rays and ends with the other ray.
This implies that the two extreme rays of a pointed cone in {{{R^2}}} non-
adjacent. Which is obviously wrong: these rays have a common vertex, which
is an element of the polyhedron of dimension one less, and due to this
they are adjacent, just as two facets of a polytope in {{{R^3}}} would be
adjacent if they had a common edge (or two edges would be adjacent if they
had a common vertex).
Did you mean to say ''more than 1 vertex'', rather than ''vertices''?
Why does it only talk about polygons? What about bigger dimensions?
There is a typo on line 261 of {{{geometry/polyhedron/base.py}}}:
exact->exactly
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13638#comment:7>
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