Ticket #4136 (closed defect: fixed)

Opened 3 months ago

Last modified 1 month ago

[with patch, positive review] enable tail reduction when reducing multivariate polynomials

Reported by: malb Assigned to: malb
Priority: major Milestone: sage-3.2
Component: commutative algebra Keywords:
Cc:

Description

This was reported on [sage-support]: 

hi there,

this is going to be even worse than my recent bug report in terms of
reproducing the error. I guess i'll start with describing what
happens, and then if someone tells me that it's a bug and not a
feature, then i'll try to get a minimal example.

So I've got a polynomial ring with a few dozens variables, over a
cyclotomic field, and i've got an ideal J with hundreds of generators.
J contains at least y9 + y12. Then i got something like:

sage: J.reduce(y9 - y12)
2*y9   #which is fine

sage: J.reduce(y13*y15)
y13*y15 #why not

sage: J.reduce(y13*y15 + y9 - y12)
y13*y15 + y9 - y12

Now what's up with that ? shouldn't it be y13*y15 + 2*y9 ? that's what
i expect from the term 'reduction' anyway. Is this normal or is it a
bug ? if it's a bug, could it influence the equivalence x in J iff
J.reduce(x) == 0 ?

So if this is a bug i'll give you more details.

thanks!
Pierre

http://groups.google.com/group/sage-support/browse_thread/thread/138e473f31c2f2b5 


   

  







Attachments

  

   
tail_reduce.patch (1.3 kB) - added by malb on 10/20/2008 06:20:34 AM.






Change History



 

 

  

    
    09/20/2008 08:49:01 AM changed by malb
  

   
    
    
  • status changed from new to assigned.
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    10/16/2008 11:24:01 PM changed by PolyBoRi
  

   
    
    
  • summary changed from [with patch, needs review] enable tail reduction when reducing multivariate polynomials to [with patch, positive review] enable tail reduction when reducing multivariate polynomials.
    • 
    
   

  

it's ok.




 

 

 

 

  

    
    10/20/2008 04:53:20 AM changed by mabshoff
  

  

Mhhh, what are the patch dependencies here?



mabshoff@sage:/scratch/mabshoff/release-cycle/sage-3.2.alpha0/devel/sage$ patch -p1  < trac_4136_tail_reduce.patch 
patching file sage/rings/polynomial/multi_polynomial_element.py
Hunk #1 FAILED at 1485.
Hunk #2 FAILED at 1511.
2 out of 2 hunks FAILED -- saving rejects to file sage/rings/polynomial/multi_polynomial_element.py.rej


Cheers,




Michael




 

 

 

 

  
10/20/2008 06:20:34 AM changed by malb
  

   
    
    
  • attachment tail_reduce.patch added.
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    10/20/2008 06:21:00 AM changed by malb
  

  

I rebased the patch to 3.1.3




 

 

 

 

  

    
    10/20/2008 07:32:34 AM changed by mabshoff
  

   
    
    
  • status changed from assigned to closed.
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  • resolution set to fixed.
    • 
    
   

  

Merged in Sage 3.2.alpha0