#18250: G.triangles_count speedup
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Reporter: | Owner:
ncohen | Status: positive_review
Type: | Milestone: sage-6.7
enhancement | Resolution:
Priority: major | Merged in:
Component: graph | Reviewers: Vincent Delecroix
theory | Work issues:
Keywords: | Commit:
Authors: | fd88c98cfc2fee8d0750cd9b6f88d1d7b8177ed4
Nathann Cohen | Stopgaps:
Report Upstream: N/A |
Branch: |
public/18250 |
Dependencies: |
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Comment (by ncohen):
> Can you tell me what you mean by "specificities of the backends"?
If you actually mean "specificities of the backens" (and not about the
Multi,looped,edge-labelled) graph), then what I want to do is merely to
make it simple to switch from one to the other, for the user or for the
coders. I am trying to clean the constructor first (#18185 in
`needs_review`), then I will try to make it a bit faster (creating
immutable copies is unnecessarily complicated), to distribute them a bit
(into subfunctions).
The main problem I haven't solved is this: what should the *default*
backend for Sage graphs be?
For small graphs I expect that the current one is right. But being able to
run "has_edge" in `log(n)` time, or being able to remove edges has a huge
cost. If we just want to add edges and vertices (i.e. to build graphs,
from an algorithm or from a file) then it can be MUCH cheaper. For
analysis of large networks it is something that you cannot afford to pay,
and then this backend must be different.
So if we want to make no choice at all, it really has to become much
simpler and natural to pick a backend for a graph.
Also, we may want to have a 'virtual' backend like in Gap for graphs
defined from a group action. No graph would actually be stored, yet all
algorithms should be available.
Well, that's what I think of these days.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/18250#comment:32>
Sage <http://www.sagemath.org>
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