-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Thomas Kahle wrote: > Hi all, > > I think I found a bug, or use singular in sage in the wrong way: > > sage: R = QQ['x1,x2,x3,x4,x5'] > sage: (x1,x2,x3,x4,x5) = R.gens() > sage: I = (x1*x4^2 - x2*x5^2, x1^3*x3^3 - x4^2*x2^4, x2*x4^8 - > x3^3*x5^6)* R > sage: I.quotient(x3*R) == I > True > sage: J = I + x1^2*R > sage: J.quotient(x3*R) == J > False
Ok, sorry about this, singular/sage are right: the statement is false. > sage: > > However, I think there is a theorem that guarantees that the last line > is true. A quick computation in pure singular shows that it is in fact > the case. Here is how to do it in singular, note that sometimes you > explicitly have to request standard bases or singular messes up things. > Could it be related to this ? > > ring R = 0,(x1,x2,x3,x4,x5),dp; > ideal I = x1*x4^2-x2*x5^2, > x1^3*x3^3-x2^4*x4^2, > x2*x4^8-x3^3*x5^6; > > std(quotient(I,x3)) > std(I) > > *** Here I compare the output manually since I dont know hot to compare > ideals in singular **** > > ideal J = I + x1^2 > > std(quotient(J,x3)) > std(J) > > > Thanks > Tom - -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkk2iK0ACgkQrpEWPKIUt7P5ZACfTC5N0c44viPCGx8gLjzW1wTk 6dQAn26RlsJhR9dVEhPsEaKlYDlM9AXo =sTju -----END PGP SIGNATURE----- --~--~---------~--~----~------------~-------~--~----~ 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://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
