On Friday, March 7, 2014 8:33:50 AM UTC-8, Nicolas M. Thiéry wrote: > > - R in FiniteSets(): > Does Sage already know that R is a finite set? > > - R.is_finite(): > Is R finite? Answering may require a lengthy calculation; A > NotImplementedError would be a valid "answer". > Shouldn't that be "Does Sage know that R is a finite set *by construction*?" If the "is_finite" result gets cached in the categories we'd violate immutability of parents, i.e.,
sage: R in FiniteSets() False sage: R.is_finite() True sage: R in FiniteSets() True would be bad. I know there are some cases where we've swallowed this badness in favour of some gains in efficiency elsewhere. I guess one could argue it's the category that gets mutated, not R, but I'm not sure that's entirely fair. -- 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.
