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Bug #509

SyzOfGens (CoCoA-5) does not have correct shifts

Added by Anna Maria Bigatti about 10 years ago. Updated about 10 years ago.

Status:
Closed
Priority:
High
Assignee:
Anna Maria Bigatti
Category:
Incomplete function
Target version:
CoCoA-5.1.0 Easter14
Start date:
03 Apr 2014
Due date:
% Done:

100%

Estimated time:
2.00 h
Spent time:
2.25 h

Description

/**/  Use R ::= QQ[x,y];
/**/  I := ideal(x^2, y^2, x+y);
/**/  G := gens(SyzOfGens(I));
/**/  IsHomog(G[1]);
false

It should be true, with the correct shifts.

2014-04-08 fixed: now return true -- still needs cleaning

Related issues

Related to CoCoA-5 - Feature #200: add modules and module operationsClosed2012-06-29

Related to CoCoA-5 - Feature #529: Naive version of resolution and Betti numbersClosed2014-04-09

Related to CoCoALib - Feature #1206: syz, SyzOfGens: which shifts for zero?Closed2018-08-02

Follows CoCoALib - Bug #510: SyzOfGens (CoCoALib): fix shiftsClosed2014-04-02

History

#1 Updated by Anna Maria Bigatti about 10 years ago

  • Target version changed from CoCoA-5.1.0 Easter14 to CoCoALib-0.99533 Easter14

#2 Updated by Anna Maria Bigatti about 10 years ago

  • Project changed from CoCoALib to CoCoA-5
  • Category deleted (Maths Bugs)
  • Target version deleted (CoCoALib-0.99533 Easter14)

#3 Updated by Anna Maria Bigatti about 10 years ago

  • Category set to Incomplete function
  • Target version set to CoCoA-5.1.0 Easter14

#4 Updated by Anna Maria Bigatti about 10 years ago

  • Due date deleted (03 Apr 2014)

#5 Updated by Anna Maria Bigatti about 10 years ago

  • Subject changed from SyzOfGens does not have correct shifts to SyzOfGens (CoCoA-5) does not have correct shifts

#6 Updated by Anna Maria Bigatti about 10 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 20
  • Estimated time set to 5.00 h

Fixed the code for adding the shifts.
Needs more testing and flexible interfaces.
This is essentially what we can do now to compute a resolution (still a bit verbose):

/**/ Use R ::= QQ[x,y,z];   I := ideal(x, y, z^2);
/**/ S := MinGens(SyzOfGens(I));  S;
[[y, -x, 0], [0, z^2, -y], [z^2, 0, -x]]

/**/ M := submodule(ModuleOf(S[1]), S);
/**/ S := MinGens(SyzOfGens(M));  S;
[[z^2, x, -y]]

/**/ M := submodule(ModuleOf(S[1]), S);
/**/ S := MinGens(SyzOfGens(M));  S;
[]

#7 Updated by Anna Maria Bigatti about 10 years ago

Now we have submodule(gens) issue #200
so this is now more compact

/**/ Use R ::= QQ[x,y,z];   I := ideal(x, y, z^2);
/**/ S := MinGens(SyzOfGens(I));  S;
[[y, -x, 0], [0, z^2, -y], [z^2, 0, -x]]

/**/ S := MinGens(SyzOfGens(submodule(S)));  S;
[[z^2, x, -y]]

/**/ S := MinGens(SyzOfGens(submodule(S)));  S;
[]

#8 Updated by Anna Maria Bigatti about 10 years ago

  • % Done changed from 20 to 50
  • Estimated time changed from 5.00 h to 2.00 h

Now that shifts is ported to CoCoA-5 more testing can be done.

#9 Updated by Anna Maria Bigatti about 10 years ago

  • Status changed from In Progress to Closed
  • Priority changed from Normal to High
  • % Done changed from 50 to 100

(Naive resolution implemented) now shifts are tested and working fine. Closing.

#10 Updated by Anna Maria Bigatti over 5 years ago

  • Related to Feature #1206: syz, SyzOfGens: which shifts for zero? added

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