I'm not really qualified to comment in detail, but I thought I would mention that I am interested in computing face lattices of polytopes as part of my polytope module. Perhaps you could comment on whether there is (or could be) anything in your code that might help me out with that.
I think its exciting that we are getting more sage-native functionality like this. Cheers, M. Hampton On Apr 23, 7:53 pm, "Franco Saliola" <[EMAIL PROTECTED]> wrote: > Dear all, > > I've posted on trac the current version of my posets code. > There is still much to be done, some algorithms need > to be improved and others need to be implemented. (There > are no NotImplementedErrors.) > > http://trac.sagemath.org/sage_trac/ticket/2519 > > But before I continue working, I'd like some feedback. I've > made some decisions, and I don't know if they are the > best decisions. So please offer suggestions. > > I've defined a HasseDiagram class that inherits from > DiGraph. A Hasse diagram are transitively-reduced, directed, > acyclic graph without loops or multiple edges. NOTE: We > assume that range(n) is a linear extension of the Hasse > diagram. This decision was taken in the hopes that it > increases the efficiency of algorithms. > > There is a FinitePoset class that stores the list of > elements of the poset (_elements), the HasseDiagram > (_hasse_diagram, or hasse_diagram()), and maps > _element_to_vertex and _vertex_to_element. So FinitePoset is > just a vertex labelling of the HasseDiagram. > > There is a constructor called Poset that takes various forms > of data describing a finite poset and returns a FinitePoset > object. > > There are also Lattice, MeetSemilattice, JoinSemilattice..., > and PosetElement, LatticeElement, .... So one create poset > elements and compare them with <, >, etc. And lattice > elements can by multiplied and added (for meet and join). > > There are a few toy posets included (eventually there > should be a poset database): BooleanLattice, Chain, > Antichain, Pentagon, Diamond, PosetOfIntegerCompositions, > RandomPoset, SymmetricGroupBruhatOrder, > SymmetricGroupWeakOrder. > > So what do you think? > > Franco > > -- --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
