#10167: three new methods in Poset
---------------------------------+------------------------------------------
Reporter: chapoton | Owner: sage-combinat
Type: enhancement | Status: new
Priority: minor | Milestone:
Component: combinatorics | Keywords: poset
Author: Frederic Chapoton | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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1) I need the distributive lattice of order ideals of a poset:
{{{
sage: Posets.PentagonPoset().order_ideals_lattice()
}}}
2) I need the poset of join irreducibles of a lattice:
{{{
sage: Posets.PentagonPoset().join_irreducibles_poset()
}}}
3) The Coxeter tranformation of a poset is a matrix, defined using the
order matrix and its inverse, which is useful in the study of the derived
category attached to the poset.
{{{
sage: Posets.PentagonPoset().coxeter_transformation()
}}}
My procedure for the distributive lattice seems to be broken right now. N.
Thiery has a procedure for the poset of join irreducibles. I have a
working procedure for the Coxeter transformation.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10167>
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