Just adding a link to a track ticket that is relevant:
http://trac.sagemath.org/ticket/16403
On Monday, July 8, 2013 12:23:21 PM UTC+2, vdelecroix wrote:
>
> Hi,
>
> I do like the project find_stat but do not like the way it intends to do
> it. In that sense, I mostly agree with Nathann objections.
>
> Following Thierry, why combinatorial maps are not implemented as morphisms
> between two proper parents ? We could add some semantic to morphisms
> (injectivity/surjectivity/bijectivity, ...) which is definitely useful.
> Note that some semantic is already there as a morphism might be a map
> between sets or a map between between graded objects. It is possible to
> implement a decorator that actually creates a morphism from a method
> (@morphism_from_method) and cache it somewhere. I think that it should not
> transform a method to a combinatorial map (which was one of the main
> Nathann's objection) but it might be useful that such decorator exists.
> Then, the problem is what method is not an actual morphism between two
> parents (do we want decorators everywhere) ? Where do we register the
> morphisms (in the parent, in a database) ?
>
> Another problem is that given a parent, it is not possible to determine
> all the morphisms from or to that parent ("possible" here means that such
> function will never exists, because most of the objects and morphisms are
> dynamically created with the coercion framework and that set of morphisms
> is potentially infinite). Nevertheless, coercion framework takes care about
> somewhat "natural" morphisms and combinatorial maps are somewhat opposite
> (ie non trivial transformations). But still, some semantic might be applied
> to coercion morphisms.
>
> There are several obstruction to such project:
> - an object (let say the partition [3,2,1]) may have several parent
> (Partitions of 6, Partitions graded by the length, ...) but the
> combinatorial map exists somewhat independently of the parent
> - we need to convince Nathann that it would be good to have the parent
> Graphs ;-)
>
> Best
> Vincent
>
--
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.
