See http://trac.sagemath.org/ticket/15745
John On 27 January 2014 14:39, John Cremona <[email protected]> wrote: > On 27 January 2014 14:37, <[email protected]> wrote: >> Ok, I will do the upstream-report (Singular trac at >> http://www.singular.uni-kl.de:8002/trac/newticket) >> >>> John Cremona: [...] which I'm sure has been reported before. >> >> >> I could not find a corresponding ticket in sage trac and cannot >> currently login. Could someone open a that ticket in sage-trac if necessary? > > I will do that (unless Peter has already). Despite Singular, Sage > can check for the unit ideal in this and related functions. > > John > >> >> >> Jack >> >> Am Montag, 27. Januar 2014 15:15:08 UTC+1 schrieb Peter Bruin: >>> >>> Hello, >>> >>> > I'm a bit confused about Sage's answer if Ideal(1) is prime. >>> > >>> > R.<x,y>= QQ[] >>> > I = Ideal(R(1)) >>> > I.is_prime() >>> > >>> > Sage (5.11, not only) says yes, >>> > conflicting to the definition, >>> > http://en.wikipedia.org/wiki/Prime_ideal >>> > Has somebody an expanation of this behaviour? >>> >>> The example Singular session below suggests that the problem lies in >>> Singular (I'm not too familiar with Singular, but I think the answers >>> should all be the same, and only primdecSY(J) seems to be correct). >>> >>> Peter >>> >>> >>> $ sage -singular >>> SINGULAR / >>> Development >>> A Computer Algebra System for Polynomial Computations / version >>> 3-1-5 >>> 0< >>> by: W. Decker, G.-M. Greuel, G. Pfister, H. Schoenemann \ Jul 2012 >>> FB Mathematik der Universitaet, D-67653 Kaiserslautern \ >>> > LIB "primdec.lib" >>> (...) >>> > ring R = 0, (x, y), dp; >>> > ideal I = 1; >>> > primdecSY(I); >>> [1]: >>> [1]: >>> _[1]=1 >>> [2]: >>> _[1]=1 >>> > primdecGTZ(I); >>> [1]: >>> [1]: >>> _[1]=1 >>> [2]: >>> _[1]=1 >>> > ideal J = x, x + 1; >>> > primdecSY(J); >>> empty list >>> > primdecGTZ(J); >>> [1]: >>> [1]: >>> _[1]=1 >>> [2]: >>> _[1]=1 >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "sage-support" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/sage-support. >> For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.
