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Bug #1420

IdealOfProjectivePoints and MinGens: problem with CoCoA_ASSERT

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

Status:
Closed
Priority:
High
Assignee:
Anna Maria Bigatti
Category:
bug
Target version:
CoCoA-5.3.0
Start date:
18 Feb 2020
Due date:
% Done:

100%

Estimated time:
1.50 h
Spent time:
1.45 h

Description

I compiled CoCoALib (and CoCoA-5) with debugging active. The last test in exbug.cocoa5 fails

use P ::= QQ[x,y,z];
K := IdealOfProjectivePoints(P,mat([[0,1,1],[0,0,1]]));
MinGens(K);

The problem is a failed assertion:

==== CoCoA Assertion failed: [[myGBasisValue.empty()]]
==== File: SparsePolyOps-ideal.C
==== Line: 737

Related issues

Related to CoCoALib - Bug #1416: IdealOfProjectivePoints and MinGensClosed2020-02-14

Related to CoCoALib - Design #1422: Remove flag IhaveGBasisValue?In Progress2020-02-25

History

#1 Updated by John Abbott about 4 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 10

The problem is in the fn myGBasis

The impl has too many assertions that myGBasis is empty; just a single assertion (in the right place) should suffice!
The code looks dodgy to me...

#2 Updated by John Abbott about 4 years ago

  • Description updated (diff)

#3 Updated by Anna Maria Bigatti about 4 years ago

  • Related to Bug #1416: IdealOfProjectivePoints and MinGens added

#4 Updated by Anna Maria Bigatti about 4 years ago

  • Related to Design #924: FlagManager for bool/bool3 flags added

#5 Updated by Anna Maria Bigatti about 4 years ago

  • Subject changed from IdealOfProjectivePoints to IdealOfProjectivePoints and MinGens: problem with CoCoA_ASSERT
  • Status changed from In Progress to Resolved
  • Assignee set to Anna Maria Bigatti
  • Priority changed from Urgent to High
  • % Done changed from 10 to 50

#6 Updated by Anna Maria Bigatti about 4 years ago

  • Related to Design #1422: Remove flag IhaveGBasisValue? added

#7 Updated by Anna Maria Bigatti about 4 years ago

  • Related to deleted (Design #924: FlagManager for bool/bool3 flags)

#8 Updated by Anna Maria Bigatti about 4 years ago

  • Target version changed from CoCoA-5.3.0 to CoCoA-5.4.0

This problems comes from the fact that IdealOfProjectivePoints computes a GBasis, without determining the minimal generators.
The function MinGens, then has to run myGBasis, with Buchberger Algorithm, to find the minimal generators, effectively forgetting that the ideal already has a GBasis.

The quick&easy solution to #1416 was to set IhaveGBasisValue = false; to force the call.
But now the assert complains the assert in myGBasis (only when debugging is on) finds the mismatch.

Deciding and solving #1422 will solve this issue too.

#9 Updated by Anna Maria Bigatti about 4 years ago

  • Status changed from Resolved to Closed
  • Target version changed from CoCoA-5.4.0 to CoCoA-5.3.0

commented out ASSERT.
This may be closed, leaving Design #1422 to do for next release.

#10 Updated by John Abbott about 4 years ago

  • % Done changed from 50 to 100
  • Estimated time set to 1.50 h

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