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Bug #994

SEGV: Toric example from Kazuki Maeda

Added by John Abbott over 7 years ago. Updated about 7 years ago.

Status:
Closed
Priority:
Urgent
Assignee:
Anna Maria Bigatti
Category:
enhancing/improving
Target version:
CoCoA-5.2.0 spring 2017
Start date:
09 Jan 2017
Due date:
% Done:

100%

Estimated time:
6.01 h
Spent time:
5.10 h

Description

2017 is starting well... :-/

Kazuke Maeda reports the following SEGV problem:
The following repeated computation eventually causes SEGV

Use R::=QQ[x[1..21]];
S:=[[1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
    [1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
    [0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0],
    [0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1],
    [0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1]];
For I:=1 To 1000 Do
    PrintLn I;
    T:=toric(S);
EndFor;

On Linux 64-bit the SEGV happens after 56 iters.
On my MacBook it happens after 33 iters.
Kazuki says that 122 iters are needed on M$ Windoze.

History

#1 Updated by John Abbott over 7 years ago

JAA has confirmed the bug (using current internal CVS version).

Marked as urgent because it triggers SEGV, and we hope to release a new version very soon.

I have placed this under CoCoA-5 rather than CoCoALib because it was reported by a CoCoA-5 user (with aCoCoA-5 example triggering the problem). JAA strongly suspects that the problem actually lies in Anna's old "toric" code; though it is strange that the problem has not arisen before.

We should email Kazuki when the bug has been corrected (hopefully soon!)

#2 Updated by John Abbott over 7 years ago

I'm trying to compile CoCoA-5.1.5 on my netbook (after a clean reinstall of the system).

To my surprise BOOST installation failed very fast... there was no C compiler! 8-O
Luckily EduRoam was cooperative today, so I could install the compiler (and then BOOST without having to compile it).
Next surprise: I wanted to compile GMP with C++ extension (this involved installing m4 for configuration), but compilation failed... there was no make command! 8-O

#3 Updated by Anna Maria Bigatti over 7 years ago

investigating.
On my Mac 33.

#4 Updated by Anna Maria Bigatti over 7 years ago

  • Assignee set to Anna Maria Bigatti
  • % Done changed from 0 to 10

reduced to

use R ::= ZZ/(2)[x[1..12]];

J := ideal(
 x[4]*x[10] +x[3]*x[11],
 x[4]*x[10] +x[2]*x[12],
 x[4]*x[6]*x[10] +x[3]*x[5]*x[12],
 x[3]^2*x[5]*x[9] +x[1]*x[4]*x[6]*x[10],
 x[3]*x[9] +x[1]*x[12],
 x[8]*x[10] +x[7]*x[11]
       );

toric(J);

#5 Updated by Anna Maria Bigatti about 7 years ago

  • % Done changed from 10 to 90
  • Estimated time set to 6.01 h

definitively a bug: "n" instead of "Indices[n]" in the preprocessing.
Obviously a very rare case.

#6 Updated by Anna Maria Bigatti about 7 years ago

  • Status changed from New to Feedback

#7 Updated by Anna Maria Bigatti about 7 years ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100

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