#13808: Gromov hyperbolicity of graphs
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Reporter: dcoudert | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.6
Component: graph theory | Resolution:
Keywords: graph, hyperbolicity | Work issues:
Report Upstream: N/A | Reviewers:
Authors: David Coudert | Merged in:
Dependencies: | Stopgaps:
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Comment (by dcoudert):
Hello,
1. Yes we can define a structure to store extremities of paths, but I'm
not so sure it is totally free. I agree it could be easier to read.
1. I agree with proposed improvement of documentation
1. Concerning the uint64_t. I did some tests with very large graphs, so it
was useful at least for me (I also used that type to count number of
visited 4-tuples although it is not part of this patch). Furthermore, I'm
not so sure we can use int instead, and clearly unsigned int or unsigned
long int would be harder to read that uint64_t.
1. Number of paths: you are right. The proposed modification clarifies the
doc.
1. elimination_bucket: The patch is ready to host any heuristic/algo able
to identify vertices that could be eliminated as soon as the lower bound
is 2 or 3 or more. However, as discussed by mail, I don't have efficient
ways to identify such vertices yet. Since the extra cost is negligeable, I
suggest to let it as it (including comments).
1. sage_calloc: was not aware of it. is it safe? stable? can we safely use
it if we use structures instead of arrays of numbers?
1. extra tmp variable: since the function _invert_cells is inlined, it
means each execution would have to instantiate a new variable. I'm not
sure it is better/faster than current implementation.
1. the a.patch is OK.
D.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13808#comment:9>
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