On Thu, Apr 24, 2008 at 10:19 AM, John Cremona <[EMAIL PROTECTED]> wrote: > > I think this is because the underlying computer algebra system Sage > uses for univariate polynomial rings and multivariate rings are > completely different, so support different operations. > > Someone else might be able to suggest a work-round.
I think the best workaround is to implement it and post a patch. :-) > > 2008/4/24 UAT <[EMAIL PROTECTED]>: > > > > > > For some reason, there is no covering morphism available for the > > quotient ring QQ[X]/(X^2). But when I take the polynomial ring in two > > variables, everything is fine: > > > > sage: R.<X> = PolynomialRing(QQ) > > sage: S = R.quo(X^2) > > sage: S > > Univariate Quotient Polynomial Ring in Xbar over Rational Field with > > modulus X^2 > > sage: S.co (I pressed TAB here) > > S.coerce_map_from S.coerce_map_from_impl > > S.construction > > sage: S.co > > > > And now: > > sage: R.<X,Y> = PolynomialRing(QQ) > > sage: S = R.quo(X^2) > > sage: S > > Quotient of Multivariate Polynomial Ring in X, Y over Rational Field > > by the ideal (X^2) > > sage: p = S.cover() > > sage: p(X)*p(X) > > 0 > > sage: > > > > So, in two variables, everything is fine! > > > > My SAGE version is: > > sage: version() > > 'SAGE Version 3.0, Release Date: 2008-04-21' > > > > > > > > > > > -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
