#19197: LatticePoset: add breadth()
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: new
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__|
8d81130c3ea697cbfe3ce178dd5a7fac052e78d3
Dependencies: | Stopgaps:
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Comment (by jmantysalo):
Replying to [comment:2 ncohen]:
> So here is a way out: enumerate all locally minimal sets directly, in
increasing order of size. This can be done with
`subsets_with_hereditary_property` [1], to which you can feed a function
that detects if a given set of points is locally minimal (when you remove
only one element).
>
> This should do the trick, and *use* the information that <some given set
of size 3 is not locally minimal> when trying to figure out one of size 4.
OK... So you think something like
{{{
f = lambda ac: self.is_antichain_of_poset(ac) and self.join(ac) not in
[self.join(set(ac).difference(set([e]))) for e in ac]
l = list(subsets_with_hereditary_property(f, self))
len(l[-1])
}}}
? Seems faster, but still stucks for 132-element
`Posets.TamariLattice(6).canonical_label()`. Btw, what is faster way to
iterate over "list `L` minus an element for every element"?
--
Ticket URL: <http://trac.sagemath.org/ticket/19197#comment:5>
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