On Wednesday, August 12, 2015 at 10:32:49 PM UTC+2, Nils Bruin wrote: > > Yes, and I agree that we'd be deviating very far from the mathematical > norm if we'd let `==` mean anything else for group elements. It also means, > as Volker points out, that in group presentations where we don't have a > solution to the word problem, we don't have equality testing (and hence, > certainly no hash either). There are groups, though, where we can solve the > word problem. There `==` works. As Nathann points out, > groups.presentation.Cyclic(4) is one. >
In many cases where we can solve the word problem we just use canonical representatives from the get-go. So there == would still do what you would naively expect even when comparing presentations in a given parent. But when we can't we should't pretend that we can magically solve the word problem. I'd take something that lets me write effective algorithms any time over an ideologically pure but useless implementation. -- 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.
