#18972: twographs and Seidel switching
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Reporter: dimpase | Owner:
Type: defect | Status: new
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 | b76c9a0369a5babc98481d6b96125c9b86f1adc9
Dependencies: | Stopgaps:
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Comment (by ncohen):
> why, why... Tutte won't complain from the grave, but, you know, to me
this feels like dancing on his tombstone...
Well, I don't like much that all graphs constructors end with "Graph" but
it's like a 'standard' problem. We either change them all, or none of
them. And in the case of upper cases for family names, I expect that Sage
has many occurrences of that.
> Seidel adj.mat. has interesting spectral properties, and that's why it
is there.
> (one gets srgs out of it if it has just 2 distinct eigenvalues; as well,
it is a means to construct cospectral graphs, by switching---which is
matrix conjugation, and this is why you preserve the spectrum...)
>
> So it is very useful on its own right.
I personally don't see the added value with respect to the adjacency
matrix. For sure it is not needed as far as the switching method is
concerned.
> OK; should there also be something done in src/doc ?
nonono, that's only needed when you create a new file.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/18972#comment:3>
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