On Thu, Mar 17, 2011 at 8:22 PM, Andrey Novoseltsev <novos...@gmail.com> wrote: > On Mar 17, 8:59 pm, William Stein <wst...@gmail.com> wrote: >> On Thu, Mar 17, 2011 at 7:39 PM, Andrey Novoseltsev <novos...@gmail.com> >> wrote: >> > Hello, >> >> > Is it desired behaviour that it is possible to create polynomial rings >> > with the same variable names?.. >> >> You're asking this because obviously this must have caused somebody >> (you?) a lot of confusion. So, what was it that caused so much >> confusion? >> >> -- William > > Hi William, > > For now it just surprised me: I wrote this while thinking about order > of generators and eliminating redundant ones in general (long story at > http://trac.sagemath.org/sage_trac/ticket/10140#comment:28). But if it > happened in practice I definitely would be quite confused and I am not > sure how easy it would be to trace the problem. I had recently an > issue due to using something like PolynomialRing(QQ, 0, "x") and the > symptoms were a bit strange. > > It seems to me that when one writes Q[x, x] in "real life" then one > means Q[x]. I also don't see how anyone can use a polynomial ring in > two different variables with the same name. So it looks like a bug to > me, I think QQ["x, x"] should either return QQ["x"] or raise an > exception. Of course, if nobody had issues with it for many years, > maybe we just should not worry.
As another data point, Magma does exactly the same thing: > R<x,x> := PolynomialRing(Rationals(),2); > R.1 + R.2; x + x -- William -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
