id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
10167,three new methods in Poset,chapoton,sage-combinat,"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 now works. N. Thiery has provided a procedure for the poset of join irreducibles. I have written a working procedure for the Coxeter transformation. They are all included in the patch below.
Notes: those changes are now included in #10998; this ticket can be closed as soon as #10998 will go in.",enhancement,closed,minor,sage-duplicate/invalid/wontfix,combinatorics,duplicate,poset,sage-combinat,,"Frédéric Chapoton, Nicolas Thiéry",,N/A,,,,,