On Tuesday, August 14, 2012 1:27:49 PM UTC-7, Simon King wrote: > > ["Followup-To:" header set to gmane.comp.mathematics.sage.algebra.] > On 2012-08-14, John H Palmieri <jhpalm...@gmail.com <javascript:>> wrote: > > ------=_Part_11_31037299.1344973817229 > >> What about just "dual"? By default, it would compute the dual with > >> respect to the category to which it belongs, and we can allow > >> customization like so: > > > > > >> sage: H.dual(category=VectorSpaces(QQ)) > >> ... a vector space ... > >> > > > > I think "H.dual()" is good. Specifying a category like this also, as > well as > > > > sage: VectorSpaces(QQ)(H.dual()) > > Start with an object O in some category C1, take its dual D in C1, and > apply > the forgetful functor to map it to a sub-category C2; one would not always > get > the same result as if one first applies the forgetful functor to O and > then > dualise the result in C2, right? > And hence VectorSpaces(QQ)(H.dual()) might (perhaps not here, but in other > situations) be different from (VectorSpaces(QQ)(H)).dual(). Would that > be a problem? >
I agree that they might be different in some situations, but I also think it's clear what each means: either dualize first or apply the forgetful functor first. Anyway, I don't think it's a problem. (My original message might have said the wrong thing, though.) -- John -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/6qBXMyQrZeMJ. To post to this group, send email to sage-combinat-devel@googlegroups.com. To unsubscribe from this group, send email to sage-combinat-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sage-combinat-devel?hl=en.
