Hey Jori, The short version why is_lattice is in the category is that *every* finite poset can check if is a lattice (if it has implementations to check if it's a join and meet semilattice). In fact, I would argue that there are many methods of the current implementation of FinitePoset (with no 's', i.e., not the category) that could be moved into the category because all objects of the category of finite posets should have them. Now why is_distributive_lattice only a part of the Hasse diagram, I'm not quite sure. The antichains in the category is an abstract method (note the decorator for the method).
In my experience, most people read the documentation in Sage using `?` rather than the reference manual. So it's not a matter of where the method is defined (you can think of the category like an ABC in this case). Best, Travis On Monday, August 25, 2014 3:23:30 PM UTC+9, Jori Mantysalo wrote: > > Let us imagine a person reading > > > http://www.sagemath.org/doc/reference/combinat/sage/combinat/posets/posets.html > > > It starts saying "implements finite partially ordered sets", so there is > no support for infinite posets. > > This page tells a reader about has_bottom() and has_top(), and there is > also is_bounded() already. But for is_join_semilattice() ja > is_meet_semilattice() there is no is_lattice(). > > Well, there is. It is here: > > http://www.sagemath.org/doc/reference/categories/sage/categories/finite_posets.html > > > So, why is part of code in categories/*.py? > > Then, how about is_distributive_lattice()? There it is: > > http://www.sagemath.org/doc/reference/combinat/sage/combinat/posets/hasse_diagram.html > > <http://www.google.com/url?q=http%3A%2F%2Fwww.sagemath.org%2Fdoc%2Freference%2Fcombinat%2Fsage%2Fcombinat%2Fposets%2Fhasse_diagram.html&sa=D&sntz=1&usg=AFQjCNH46tqTLCw0BKnZzO7b4eQrjFx86g> > > But how to call it? > > And last, why is there antichains() documented in two places, > /combinat/posets/posets and /categories/finite_posets? > > Confused am I. > > -- > Jori Mäntysalo > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
