#19197: LatticePoset: add breadth()
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/latticeposet__add_breadth__|
33610ad2c4327679b8dfc1d3af445fe4d9080e4a
Dependencies: | Stopgaps:
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Comment (by ncohen):
Hello Jori,
Here is a first-pass review while on the bus.
- I was very surprised to see a 'distance' argument in the depth-first-
search
function. You do not compute the 'distance' when running a
depth-first-search. At least not the usual notion of distance in graph
theory. We should probably remove it, as it is *highly* dangerous to
advertise
it this way `O_o`
- In your code, please use breadth-first-search instead.
- Definition of 'elems': this line often test for containment in
'too_close'. Do
not run containment tests in a list. use a 'set' for that: containment
is
faster.
- Anyway, you probably should do this differently, i.e. with
`breadth_first_search(report_distance=True)` while filtering 'too close'
elements according to their distance.
- I still believe that it would be faster to use
'subsets_with_hereditary_property' inside of your code. It would also
make the
code slightly clearer, as the test you perfom on each antichain would be
an
independent function.
- Why do you deal with breadth 2 differently from the rest? That could
mean a
couple more operations, but compared to everything else that should not
mean
much.
Besides that, congratulations for this algorithm. It works, and it works
well.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/19197#comment:15>
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