Dear David, dear Javier, On Fri, Oct 23, 2009 at 05:23:15PM +0200, David R. Kohel wrote: > I put of positive review of most of the assigned category files.
Excellent! Thanks much! > Note that I hadn't downloaded those attributed to Javier, so these > are still outstanding. Feel free to beat him to it, starting from the end of the list :-) > I made a few comments (mostly regarding the lines "TODO" in the > files). Some are probably historical, but I guess the examples might > crash if the relevant implementations are not in place in Sage > upstream. Thanks for reminding me about this. For the modules file, I just removed all (but one) "todo: not implemented", since #6136 is now ready, and can get into Sage at the same time as the category code. I am now having a look at your comments on the wiki. > I am also still not comfortable with the "with_basis" categories. I > think there are already classes which handle these Concrete classes sure. But not abstract classes for factoring generic code out of the many concrete implementations of modules with basis: (Combinatorial)FreeModule, matrix spaces, polynomials, ... > and the "with_basis" is redundant if it is not a structure to be > preserved by morphisms (like for pointed sets as distinct from > sets). It's not redundant, because it specifies how the elements are represented by expanding them on the basis, which is not always desirable or even possible (lazy power series, or functions from R to R definitely form a module, but the basis is not constructive). In turn, this information on the representation of elements yields generic algorithms. For another example of extra information carried by those *with_basis categories, an object in GradedAlgebrasWithBasis is not just a graded algebra; the elements of the distinguished basis must also be homogeneous. Yeah, I know; all of that should be stated explicitly in the doc. We haven't yet finished porting all of this info from MuPAD's doc. Best, Nicolas PS: > Doing sage -combinat install I get the following error on start-up: > > SyntaxError: Non-ASCII character '\xc2' in file > /usr/local/sage-4.1.2/local/lib/python2.6/site-packages/sage/combinat/__init__.py > on line > 22, but no encoding declared; see http://www.python.org/peps/pep-0263.html > for details > (__init__.py, line 21) Good catch. Should be fixed in a couple minutes. -- Nicolas M. ThiƩry "Isil" <nthi...@users.sf.net> http://Nicolas.Thiery.name/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. 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 -~----------~----~----~----~------~----~------~--~---