Even before getting to Laurent series, multivariate power series are harder to define than you might think, so I would avoid implementing them at this point unless you have a specific need for them! You need to be really careful since K[[x]][[y]], K[[y]][[x]] and K[[x,y]] are not all the same.
There are probably people on the list more knowledgeable than me about this, but I thought it might be worth while posting a warning! John On 16/11/2007, David Roe <[EMAIL PROTECTED]> wrote: > Hey all, > At some point in the near future I may try to bring the implementation of > power series rings more into line with the p-adics. The single variable > case seems straightforward, but a something popped up for me when thinking > about the multivariable case. > > What is the appropriate analogue of laurent series? Is the key point for > laurent series that we allow bounded negative exponents? Or that it's a > field? Because allowing bounded negative exponents is not enough to always > have inverses: x + y has no inverse if we require the exponents of x and y > to be bounded away from negative infinity. > David > > > > -- John Cremona --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
