#15278: Hash and equality for graphs
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Reporter: SimonKing | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: graph theory | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/SimonKing/ticket/15278 | 2fc8a772ee12fce7ac6abc4ecf9916f4746f5ee2
Dependencies: #12601, #15491 | Stopgaps:
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Comment (by SimonKing):
Replying to [comment:35 ncohen]:
> HMmmmmm okay. Though I really have no clue what the changes you made to
cachefunc.pyx do `O_o`
Hein? My branch doesn't touch cachefunc.pyx at all! And why should it?
> Is this related to this patch, or is it independent of immutable graphs
and thus could be made into another trac ticket, on on which this one
would depend ?
I don't even have a clue what you mean by "this". You have provided a
"static" backend that is almost enough to produce immutable graphs. To
really make them immutable (in the sense stated repeatedly), it was needed
to allow `G.weighted()` but disallow `G.weighted(new_value)` on immutable
graphs, since the latter would mutate the graph. And if something is
immutable then it makes sense to provide it with a hash---which in the
case of graphs means to provide the `._immutable` attribute---and to make
the hash faster (by using work on @cached_method that has already been
done in #12601).
So, that's what this ticket is about. Or is there anything I forgot?
And my next aim is to continue work on #12630. There, it is useful to have
hashable (immutable) (di)graphs that can be used as cache keys.
--
Ticket URL: <http://trac.sagemath.org/ticket/15278#comment:36>
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