Dear Maximilian,
Thanks for the report and in particular the specific example!
On Mon, Jan 10, 2011 at 02:30:00PM +0100, Maximilian Schlund wrote:
> while experimenting with some random partial Latin squares I have
> come across some squares for which the is_completable() Call seems
> to loop indefinitely - i.e. I had to kill sage to abort it (it was
> not responding to Ctrl+c) after running for several minutes ... I
> even once let it run for some hours with no result.
> The machine is an Intel i5 with 2.4 GHz so it should not really be
> an issue of speed I hope. (usually these instances are solved within
> 1 second)
>
> One example is the following 16 x 16 partial Latin square:
> ...
I leave it to some "Latin Square in Sage" expert to answer in detail!
But it has been running for the last couple minutes on my machine. If
you don't hear from me, that means it is indeed hanging forever (or
that I got bored and killed it).
> If it really is a bug in the solver (i.e. dancing links
> implementation) it might not be so easy to track it down ...
That would sound scary indeed!
> I stumbled upon it while generating many random partial Latin squares
> (it has not yet happened for squares smaller than 15x15)
Ok.
Best regards,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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