#20509: khovanov homology of links
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Reporter: mmarco | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-7.2
Component: algebraic | Resolution:
topology | Merged in:
Keywords: knots | Reviewers:
Authors: Miguel Marco | Work issues:
Report Upstream: N/A | Commit:
Branch: | c3dfb06199943646ad2e06ee6ca2f0ded5321270
u/mmarco/khovanov_homology_of_links| Stopgaps:
Dependencies: |
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Comment (by tscrim):
Replying to [comment:7 mmarco]:
> Indeed, it is the value of "bases" what we reuse, but that is a
dictionary, and hence mutable. Again, we could have it in a tuple format
and convert it to dictionary each time we recover it.
In this case, I would say that is okay because user does not see it (but
we should put a big warning to any developers to not mutate nor expose
it).
> In general, what to compute and cache each time is quite tricky here.
Now we are computing all the bases of the chain complexes once and caching
it. So if the user just asks for a given height, we compute a lot that we
don't need. Anyways, my experience is that the biggest part of the
computation is taken by computing the cohomology of the complexes, so it
is not so bad.
It is probably worthwhile to see what `%prun` tells us.
However, [comment:8 John's suggestion] of creating a dedicated class for
Khovanov homology is probably best because this allows us to (potentially)
give it a module structure, have full control over output, better
localization of code/caching, and make it more functor-like.
--
Ticket URL: <http://trac.sagemath.org/ticket/20509#comment:9>
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