#18972: twographs and Seidel switching
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Reporter: dimpase | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: graph theory | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/dimpase/seidelsw | 5115728f80aa95f87a272feec999e317ccdffba4
Dependencies: #18960, #18948 | Stopgaps:
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Comment (by dimpase):
Replying to [comment:23 ncohen]:
> I already made comments on the code of `seidel_switching`,
You said there that Graph.vertices() is a plain list, and I should
make it a set, or something? (I guess a dictionary, as I need to know
the original indices)
It's a usual operation, find positions of vertices... E.g.
how do you construct subgraphs without essentially doing this?
>and you need to document what a `twograph_descendant` is.
it's the composition of two documented functions, isn't it enough?
>I am not sure that this function should be in `Graph`, though. If it is
just a bit faster than using the `TwoGraph` class, maybe it is enough to
make it appear in a `seealso` inside of `twograph` and keep it in the
`two_graph` module.
It is a hell of lot faster for cases with more than 100 vertices, say.
`O(n^2)` vs `O(n^3)`.
>
> But really, all in all, I don't see the point of creating a new module,
a new class and 6 functions, if all it takes to build the descendant of a
graph is 5 lines of code.
Did you see the patch for Chang graphs? Do you think it is useless and
should be removed?
(IMHO, Chang graphs should be constructed this way, not the way it's done
at present).
--
Ticket URL: <http://trac.sagemath.org/ticket/18972#comment:24>
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