#13808: Gromov hyperbolicity of graphs
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Reporter: dcoudert | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.6
Component: graph theory | Resolution:
Keywords: graph, hyperbolicity | Work issues:
Report Upstream: N/A | Reviewers: Nathann Cohen
Authors: David Coudert | Merged in:
Dependencies: | Stopgaps:
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Changes (by dcoudert):
* status: needs_work => needs_review
* reviewer: => Nathann Cohen
Old description:
> This patch implements algorithms for computing the Gromov hyperbolicity
> of a graph. Although the worst case time complexity is in `O(n^4)`, the
> proposed implementation performs quite well in practice. It has been used
> on graphs with more than 10.000 vertices.
>
> APPLY:
> * [attachment:trac_13808-v2.patch]
New description:
This patch implements algorithms for computing the Gromov hyperbolicity of
a graph. Although the worst case time complexity is in `O(n^4)`, the
proposed implementation performs quite well in practice. It has been used
on graphs with more than 10.000 vertices.
APPLY:
* [attachment:trac_13808-v3.patch]
--
Comment:
I have implemented all proposed changes:
- use of a struct for pairs
- use of sage_calloc when appropriate
- use uint32_t instead of uint64_t when appropriate. These types are
shorter to write/read. Also uint64_t is needed for distributions since
number could potentially be huge (more theoretical than practical due to
huge computation time)
- improve ordering for visiting pairs
- simplify pre-processing and corresponding data structure. It now only
considers simplicial vertices.
I have merged the [attachment:a.patch] into the new version of the patch:
[attachment:trac_13808-v3.patch]. The patch is much better now, the doc is
nicer, and it is a bit faster.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13808#comment:13>
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