#9645: Bugs in the computation of Groebner bases over the integers
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   Reporter:  SimonKing            |       Owner:  duleorlovic                  
            
       Type:  defect               |      Status:  new                          
            
   Priority:  critical             |   Milestone:  sage-5.0                     
            
  Component:  commutative algebra  |    Keywords:  Groebner basis integer       
            
     Author:                       |    Upstream:  Reported upstream. Little or 
no feedback.
   Reviewer:                       |      Merged:                               
            
Work_issues:                       |  
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Comment(by SimonKing):

 Replying to [comment:4 duleorlovic]:
 > Replying to [comment:1 SimonKing]:
 >
 > > There is a new singular spkg at #8059. However, this does not solve
 the problem. The only difference is that now one has ` sage:
 I.groebner_basis(algorithm='toy:buchberger2') [2*x^2 + x*y, 3*x*y, 2*y^2]
 ` Hence, the result is reduced (the first bug is gone), but still wrong.
 >
 > Result is '''right '''because reduce is different in field and in ring
 (please read
 
[http://books.google.com/books?id=Caoxi78WaIAC&pg=PA201&dq=adams+loustaunau+introduction+to+grobner+bases+chapter+4&hl=sr&ei=CwdYTJzPHcGe4AaZsKmhBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q=adams%20loustaunau%20introduction%20to%20grobner%20bases%20chapter%204&f=false
 this book chapter 4]).
 >
 > x*y!^2  is reduced to zero on [2*x!^2 + x*y, 3*x*y, 2*y!^2] because
 x*y!^2 - (y*3*x*y-x*2*y!^2)=0.

 I don't buy this and repeat that this is not a reduction. Martin, do you
 agree?

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9645#comment:5>
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