On 12/16/13 8:14 AM, Christian Stump wrote: > I wouldn't necessarily call that a bug, as it is necessary since A == > B. > > > four people, two options, five opinions... > > Let me ask this, is being a k-core a property of a partition or is it a > /distinct/ combinatorial object? > > > As mathematical concepts, that doesn't make much of a difference, I'd say. It > is just too easy to think of something written as [4,2,1,1] at the same time > as a partition, a list, a composition, a > core, ... > > On the other hand, sagewise, if being a k-core is only a property of a > partition, why do their methods differ that much? do some methods even have > different results depending on the type of core? As > it seems this is the case, I do think of a core as a different combinatorial > object.
The reason why we need(ed) a separate core class is that for example otherwise it would not be possible or easy to implement the action of the affine symmetric group on (k+1)-cores. Of course, one can ask whether a given partition is an n-core and that method should live in Partitions, but the moment there are operations that only make sense on the set of n-cores, it seems necessary to implement a separate class. Christian, the reason why we decided that sage: la = Partition([2,2,1]) sage: la.to_core(2) [5, 3, 1] gives a 3-core (and not 2-core) is that the map goes from k-bounded partitions to (k+1)-cores. In fact, since Travis brought up the issue about a possible class for k-bounded partitions. I have some currently private code on some new methods on k-bounded partitions that I think make most sense inside a class of k-bounded partitions, but of course I could also put them straight into Partitions. What should I do? Best, Anne -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/groups/opt_out.
