Discussion related to cado-nfs

[Pierrick Gaudry <pierrick.gaudry@loria.fr>]

For those interested in a follow-up on this issue, you can follow the bug
number 21761 on the forge.

No full satisfactory answer yet, though.

Pierrick

On Mon, May 20, 2019 at 09:39:11AM +0200, Pierrick Gaudry wrote:
> Hello,
> 
> I could reproduce your problem.
> 
> There are indeed bugs (in at least 2 places) that are triggered by your
> example. One in freerel that produces wrong relations, and one in
> filter_galois that crashes. In both cases, I suspect that the local
> behavior of x^4+4*x^2+1 at p=3 is not handled correctly.
> 
> This won't be fixed right now, but will probably be this summer.
> 
> For now, there is a workaround:
> - disable Galois (you already did that);
> - disable free relations by adding the following in the parameter file
>     tasks.sieve.freerel.pmax=1
> 
> With this, I could have the Logarithms Reconstruction finish without
> error.
> 
> Regards,
> Pierrick
> 
> 
> On Sat, May 18, 2019 at 08:22:18PM +0800, Xs. X. wrote:
> > Hello everyone,
> > 
> > I'm solving a DLP problem in GF(p^2) with the polynomial built by myself,
> > and the program failed at reconstructlog-dl.
> > 
> > The command is:
> > 
> > ./cado-nfs.py -dlp 170141183460469231731687303715884123283 -ell
> > 42535295865117307932921825928971030821 -gfpext 2
> > 
> > The output is:
> > 
> > Info:Logarithms Reconstruction: Starting
> > Warning:Command: Process with PID 6202 finished with return code 1
> > Error:Logarithms Reconstruction: Program run on server failed with exit
> > code 1
> > Error:Logarithms Reconstruction: Command line was:
> > /home/xz/git/cado-nfs/build/W/filter/reconstructlog-dl -ell
> > 42535295865117307932921825928971030821 -mt 4 -log
> > /tmp/cado.l7xi344p/p2dd40.bwc/K.sols0-1.0.txt -out
> > /tmp/cado.l7xi344p/p2dd40.dlog -renumber
> > /tmp/cado.l7xi344p/p2dd40.renumber.gz -poly /tmp/cado.l7xi344p/p2dd40.poly
> > -purged /tmp/cado.l7xi344p/p2dd40.purged.gz -ideals
> > /tmp/cado.l7xi344p/p2dd40.ideal -relsdel
> > /tmp/cado.l7xi344p/p2dd40.relsdel.gz -nrels 448640 -nsm '1,0' >
> > /tmp/cado.l7xi344p/p2dd40.reconstructlog-dl.stdout.1 2>
> > /tmp/cado.l7xi344p/p2dd40.reconstructlog-dl.stderr.1
> > Error:Logarithms Reconstruction: Stderr output (last 10 lines only) follow
> > (stored in file /tmp/cado.l7xi344p/p2dd40.reconstructlog-dl.stderr.1):
> > Error:Logarithms Reconstruction:        antebuffer set to
> > /home/xz/git/cado-nfs/build/W/utils/antebuffer
> > Error:Logarithms Reconstruction:        Warning, log is zero for h = a
> > Error:Logarithms Reconstruction:        Warning, log is zero for h = 11
> > Error:Logarithms Reconstruction:        Warning, log is zero for h = 36
> > Error:Logarithms Reconstruction:        Warning, log is zero for h = 373
> > Error:Logarithms Reconstruction:        Warning, log is zero for h = 1000
> > Error:Logarithms Reconstruction:        Error, no unknown log in rel 
> > 107479
> > and sum of log is not zero, sum is: 24350889115762306525772643466974011408
> > 
> > 
> > It seems that there is a bug in DLP for GF(p^2) like bug#21707.
> > The git version is efbd21713
> > The polynomial I build is:
> > # poly0 = x^4+4*x^2+1
> > # poly1 = 
> > 7575543440937986073*x^2+7440663049042884025*x+7575543440937986073
> > (By the way, I build the polynomial with the Conjugation method. I hope 
> > I'm
> > not misunderstanding this method)
> > 
> > Regards
> > 
> > Chen Yongyan
> 
> 
> 
> > _______________________________________________
> > Cado-nfs-discuss mailing list
> > Cado-nfs-discuss@lists.gforge.inria.fr
> > https://lists.gforge.inria.fr/mailman/listinfo/cado-nfs-discuss
> 
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