Vincent I had read your post but I hadn't understood that you wanted
something like this. This Map class seems a really good idea to me, it
looks like our combinatorial map class that we use to wrap the methods but
improved.
After this discussion, the way I would see things would be:
* having a permanent database into sage containing the maps
* calling the database from the object to get create the map objects and
access the information
* using the decorator to add those maps in the database
A few questions:
- how do I use the decorator to add the maps in the database, won't it cost
time to check the database when I create the object?
- Where should we put the "combinatorial_maps" method to actually get the
list of maps on a given object (or parent)
2014-05-28 11:54 GMT+02:00 Vincent Delecroix <20100.delecr...@gmail.com>:
> Hi Christian,
>
> 2014-05-28 11:32 UTC+02:00, Christian Stump <christian.st...@gmail.com>:
> >> It seems that actually nobody read my initial post on that thread... so
> >> let me repeat
> >
> > I did -- but didn't really have any qualified contribution...
> >
> >> But the semantic has to be implemented at the level of maps not at the
> >> level of methods.
> >
> > could you explain what you mean there (maybe using your example of the
> > number of descents of a permutation).
>
> A method ( = a Python function) is not a Sage Map ( = a Python object
> that model a mathematical function). I would like first to convert the
> method into a map
> {{{
> from sage.categories.map import Map
> class NumberOfDescents(Map):
> def __init__(self):
> Map.__init__(Permutations(), NonNegativeIntegers())
>
> def _call_(self, p):
> return Integer(p.number_of_descents())
> }}}
> The above example is already non-trivial since it specifies a domain
> and a codomain (which is different from the parent of the image of an
> element):
> {{{
> sage: nod = NumberOfDescents()
> sage: p = Permutation([3,2,1])
> sage: nod(p)
> 3
> sage: nod(p).parent() is NN
> False
> }}}
> The second step would be to think how to add semantic to the map. Part
> of is already managed by the axioms/categories (for example a Morphism
> between GradedSets preserve the grading). But there is nothing for
> injectivity/surjectivity or more subtle properties.
>
> It would make more sense to register actual maps as above.
>
> Vincent
>
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