Post a reply
Username:
Note:If not registered, provide any username. For more comfort, register here.
Subject:
Message body:
Enter your message here, it may contain no more than 60000 characters. 

Smilies
:D :) :( :o :shock: :? 8) :lol: :x :P :oops: :cry: :evil: :twisted: :roll: :wink: :!: :?: :idea: :arrow: :| :mrgreen:
Font size:
Font colour
Options:
BBCode is ON
[img] is ON
[flash] is OFF
[url] is ON
Smilies are ON
Disable BBCode
Disable smilies
Do not automatically parse URLs
Confirmation of post
To prevent automated posts the board requires you to enter a confirmation code. The code is displayed in the image you should see below. If you are visually impaired or cannot otherwise read this code please contact the %sBoard Administrator%s.
Confirmation code:
Enter the code exactly as it appears. All letters are case insensitive, there is no zero.
   

Topic review - resolutions over quotient rings
Author Message
  Post subject:  resolutions over quotient rings  Reply with quote
> Hello.
>
> I ran into a confusing situation with the Singular v.1.3.8:
> I don't know if this is a bug or maybe I did something wrong, but...
> in a quotient ring mres computes a resolution which is of size 4100.
>
> SINGULAR /
> A Computer Algebra System for Polynomial Computations / version 1-3-8
> 0<
> by: G.-M. Greuel, G. Pfister, H. Schoenemann May 2000
> FB Mathematik der Universitaet, D-67653 Kaiserslautern
> > ring r=0,(a,b,c,d,e,f,g,h,i,j,k,l),Dp;
> > matrix B[2][5]=[h,i,j,k,l, 0,0,d,c,g];
> > print(B);
>
> h,i,j,k,l,
> 0,0,d,c,g
> > resolution rs=mres(B,0);
> > rs;
>
> 2 5 8 7 2 0
> r <-- r <-- r <-- r <-- r <-- r
>
> 0 1 2 3 4 5
>
> > ideal I=jg-dl;
> > qring rI=std(I);
> > matrix bee=imap(r,B);
> > print(bee);
>
> h,i,j,k,l,
> 0,0,d,c,g
>> resolution qrs=mres(bee,0);
> > size(qrs);
>
> 4100
> > qrs;
>
> // the big output omitted...
>
> by the way, using grevlex order, i.e. r=0,(a...),dp;
> seemed to ran into an unending loop.

In general, the resolution is not finite over quotient rings. One has to set a bound up to which the resolution is computed in the second argument of 'mres'. Up to Singular 2.0, unfortunately there is no such bound by default. This will change in Singular 2.1.

email: mschulze@mathematik.uni-kl.de
Posted in old Singular Forum on: 2001-05-28 14:54:45+02
Post Posted: Thu Aug 11, 2005 5:31 pm


It is currently Sun Jan 21, 2018 1:01 pm
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group