#17532: Convexity properties on graphs works incorrectly
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       Reporter:  azi           |        Owner:
           Type:  defect        |       Status:  new
       Priority:  critical      |    Milestone:  sage-6.5
      Component:  graph theory  |   Resolution:
       Keywords:                |    Merged in:
        Authors:                |    Reviewers:
Report Upstream:  N/A           |  Work issues:
         Branch:                |       Commit:
   Dependencies:                |     Stopgaps:
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Comment (by azi):

 I have verified the result in 4ways

 1. By implementing a different algorithm and getting 4 as an answer
 2. By drawing the  solution given by sage and seeing that it does not give
 the whole graph
 3. Arguing as follows. In the Petersen graph any pair of vertices is
 connected by a UNIQUE shortest path and has diameter 2. Hence 3 vertices
 give you a hull of size at most 3+ (3 \choose 2)*1 = 9
 4. By checking this paper
 http://ajc.maths.uq.edu.au/pdf/26/ajc_v26_p011.pdf where it says that the
 Petersen graph has hull number 4.

 Best,

 Jernej

--
Ticket URL: <http://trac.sagemath.org/ticket/17532#comment:2>
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