#17173: Poset: faster is_distributive_lattice
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/poset__faster_is_distributive_lattice|
d69e73a0a0a655e4e1595a77cda807ccb017fb02
Dependencies: | Stopgaps:
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Comment (by ncohen):
Hello !
> In other words: If `G.vertices()` prints `..., a, ..., b, ...`, can it
after `D.delete_edges(...)` print `..., b, ..., a, ...`? If not, is this
guaranteed behaviour in following versions of Sage?
Hmmmmm... If the vertex set consists of integers this will not happens,
but is that really a problem ? You can also store and manage the list of
vertices yourself. Or rename the set of points.
> I forgot one place where `minimal_elements()` was computed twice.
Otherwise there is no unneeded lists generated in loop.
What about this ?
{{{
len([e for e in self if len(self.lower_covers(e))==1])
if len(self.upper_covers(m))==1:
if len(M_.minimal_elements()) > 1:
}}}
nathann
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Ticket URL: <http://trac.sagemath.org/ticket/17173#comment:8>
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