We might want to think about the naming conventions for Lattice. As with all words in mathematics, this one has multiple meanings. A lattice can be a poset with a meet and a join, or it can be a free abelian group with an inner product. Normally I wouldn't bring such a thing up, but I'm working with a group thinking about implementing the latter, and you have already (it seems) implemented the former.
On Apr 23, 12:48 pm, mhampton <[EMAIL PROTECTED]> wrote: > 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 -~----------~----~----~----~------~----~------~--~---
