Tom Boothby wrote: > On Thu, Nov 19, 2009 at 4:14 PM, Florent Hivert > <florent.hiv...@univ-rouen.fr> wrote: >> Hi Jason, >> >>>> I'd like to generate all partially ordered sets of a given cardinality upto >>>> isomorphisms... They are in bijection with aclyclic, transitively reduced >>>> directed graphs. Does anyone have an idea how to do that ? I can't manage >>>> to >>>> get this with nauty. >>> >>> I'm sure there's a smarter way, but you could generate acyclic directed >>> graphs and then transitively reduce them. >> Yep ! That's a solution... I'll need then nauty again to remove isomorphic >> duplicates. I'll probably go far enough for my problem with this methods >> since >> the algorithm I want to put behind seems to be vastly exponential in the size >> of the poset. I hope this will not break my conjecture... >> >> By the way, just to know, can this be achieved in plain sage without nauty ? > > Yes, it can. Read the documentation for digraphs(). >
Using the "augment" and "property" options might also speed up your generation quite a bit, as you can control how these things are generated (i.e., you can just generate acyclic transitively reduced graphs, maybe). Nauty has similar hooks in C too. Thanks, Jason -- Jason Grout -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
