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Bug #1230

PrimaryDecomposition with lex ordering

Added by John Abbott over 5 years ago. Updated about 4 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Anna Maria Bigatti
Category:
Incomplete function
Target version:
CoCoA-5.3.0
Start date:
19 Oct 2018
Due date:
% Done:

100%

Estimated time:
1.23 h
Spent time:
1.25 h

Description

Robbiano reports the following problem:

Use P::= QQ[x,y,z];
f1:=z^2-y;  f2:= x^2 -2*x*z +y; f3:=y^2-y-z;
J:=ideal(f1,f2,f3);
PrimaryDecomposition(J);
-->  [ideal(z^2 -y,  y^2 -y -z,  x^2 -2*x*z +y,  z),  ideal(z^2 -y,  y^2 -y -z,  x^2 -2*x*z +y,  z^3 -z -1)]
-- Change ordering, same ideal
Use P::= QQ[x,y,z],Lex;
f1:=z^2-y;  f2:= x^2 -2*x*z +y; f3:=y^2-y-z;
J:=ideal(f1,f2,f3);
PrimaryDecomposition(J);
--> ERROR: NOT YET IMPLEMENTED -- please be patient, we're working on it
--> [CoCoALib] GBasisByHomog not drl

Related issues

Related to CoCoALib - Feature #1212: New function: GBasisByHomogClosed2018-08-05

Related to CoCoALib - Slug #1105: Primary Decompositon (zero-dim) slow casesClosed2017-10-02

History

#1 Updated by Anna Maria Bigatti over 5 years ago

#2 Updated by John Abbott over 4 years ago

  • Status changed from New to In Progress
  • Assignee set to Anna Maria Bigatti
  • % Done changed from 0 to 20

The given example seems to work now. Has this been fixed?
If so, close; otherwise postpone to next version.

#3 Updated by John Abbott over 4 years ago

  • Related to Slug #1105: Primary Decompositon (zero-dim) slow cases added

#4 Updated by John Abbott over 4 years ago

  • Status changed from In Progress to Resolved
  • % Done changed from 20 to 80

I think this has already been done. Changed status to "resolved".

#5 Updated by Anna Maria Bigatti over 4 years ago

  • Status changed from Resolved to In Progress
  • % Done changed from 80 to 70

Not quite :-/
there is still something dodgy:

/**/ J:=ideal(f1,f2,f3);
/**/ GBasisByHomog(J);
[y -z^2,  y^2 -z^2 -z,  x^2 -2*x*z +z^2,  y*z^2 -z^2 -z,  z^4 -z^2 -z]
/**/ PrimaryDecomposition(J);
--> ERROR: NOT YET IMPLEMENTED -- please be patient, we're working on it
--> [CoCoALib] myPrimaryDecomposition() -- general ideal
--> PrimaryDecomposition(J);
--> ^^^^^^^^^^^^^^^^^^^^^^^

#6 Updated by John Abbott over 4 years ago

This seems to work for me now.

We must add a test to exbugs.cocoa5; we can simply copy the failing case from the issue description.

Then close?

#7 Updated by Anna Maria Bigatti about 4 years ago

  • Status changed from In Progress to Feedback
  • % Done changed from 70 to 90

Seems to work now.
We did not note how we fixed the problem in comment 5. :-/
closing?

#8 Updated by John Abbott about 4 years ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100
  • Estimated time set to 1.23 h

I have added the example to exbugs.cocoa5

Closing!

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