Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: A bug in a ring with matrix ordering
PostPosted: Wed Jan 08, 2020 4:11 am 

Joined: Wed Aug 11, 2010 6:49 pm
Posts: 2
Let us create a ring with a matrix ordering:
{{{
> intmat m[3][3] = 3, 0, 1, 0, 1, 0, 0, 0, 1;
> ring R = 0, (x,y,z), M(m);
> x > 1;
1
> y > 1;
1
> z > 1;
1
}}}
Hence the monomial ordering of R is a well-ordering, and the value of internal attribute `OrdSgn` of R should be 1. But presently `OrdSgn` of R is set to -1. There seems to be a bug in the implementation of `rCheckOrdSgn` function in `libpolys/polys/monomials/ring.cc` file.

This bug was revealed while fixing a bug of Sage tracked in #28954.


Report this post
Top
 Profile  
Reply with quote  
 Post subject: Re: A bug in a ring with matrix ordering
PostPosted: Fri Jan 10, 2020 3:55 pm 

Joined: Wed May 25, 2005 4:16 pm
Posts: 275
fixed with git commit 3484489a559567285e5422a2a18fd88fb5a60600
Author: Hans Schoenemann <hannes@mathematik.uni-kl.de>
Date: Fri Jan 10 14:53:21 2020 +0100

fix: OrdSgn for matrix orderings with 0 in first row


Report this post
Top
 Profile  
Reply with quote  
 Post subject: Re: A bug in a ring with matrix ordering
PostPosted: Mon Jan 13, 2020 5:41 am 

Joined: Wed Aug 11, 2010 6:49 pm
Posts: 2
I checked that the patch works well in Sage. Thank you!


Report this post
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

It is currently Fri May 13, 2022 10:54 am
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group