#17888: Implement check for modular elements and if a poset is supersovable
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.6
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/combinat/supersolvable_posets-17888|
a15d38f0674b29e8209c952c5ad5d37911cdc722
Dependencies: | Stopgaps:
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Comment (by chapoton):
Hmm. `is_semimodular` does not seems very efficient to me. What about
something like that (not tested)
{{{
def is_supersolvable(self):
"""
"""
x0 = self.minimal_elements()[0]
x1 = self.maximal_elements()[0]
mod_elts = [x for x in self if self.is_modular([x])]
mg = DiGraph([e for e in self.cover_relations()
if e[0] in mod_elts and e[1] in mod_elts])
return mg.shortest_path(x0, x1) != []
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/17888#comment:2>
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