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Bug #1139

Radical problems

Added by John Abbott over 6 years ago. Updated over 6 years ago.

Status:
Closed
Priority:
Urgent
Assignee:
Anna Maria Bigatti
Category:
enhancing/improving
Target version:
CoCoA-5.2.2
Start date:
12 Dec 2017
Due date:
% Done:

100%

Estimated time:
1.51 h
Spent time:
1.45 h

Description

There are still problems with radical: sometimes it gives an empty list instead of an ideal.

/**/ I := ideal(x^2, x*y+1);
/**/ radical(I);
[]

Related issues

Related to CoCoA-5 - Bug #1133: Radical bugClosed2017-12-01

History

#1 Updated by John Abbott over 6 years ago

#2 Updated by John Abbott over 6 years ago

The problem seems to be when the ideal contains 1.

/**/ radical(ideal(x/x));
[]

#3 Updated by John Abbott over 6 years ago

Here is another case where things go wrong:

/**/ use QQ[x,y,z,t];
/**/ I := ideal(2*x*y*z +2*y*t,  -y^3 -x*y*t +x*t^2,  x^2*z +2*x*y*z +y^2*t);
/**/ radical(I);
-->  ERROR: I don't know how to evaluate operator + between IDEAL and LIST
-->  WHERE: at line 1105 (column 19) of radical.cpkg5

#4 Updated by John Abbott over 6 years ago

Much like the example above:

I := ideal(-x^3 -x*y^2 -x^2,  x^2*z -x^2 +y^2,  -x^2*t +x*t^2 -x*t);
I := ideal(y*z^3 +y^2*z*t,  x^2*z +2*y^2,  -x*y*t +y*z);

#5 Updated by Anna Maria Bigatti over 6 years ago

another

/**/ I := ideal(x*(x^2 -y -x),  x^2*z  +y, t);

#6 Updated by Anna Maria Bigatti over 6 years ago

  • Status changed from New to Closed
  • Assignee set to Anna Maria Bigatti
  • % Done changed from 0 to 100
  • Estimated time set to 1.51 h

Fixed: all the problem was in ideal(1).
(there is a naughty trick in ElimRedundant(E))
Now radical(I) exits I immediately if IsOne(I).

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