[gecode-users] python binding - Gecode does not find a solution on first run, finds a solution on consecutive runs.

[Christian Schulte]

I can't as I do not know how the binding is done. C

--
Christian Schulte, www.ict.kth.se/~cschulte/


> -----Original Message-----
> From: krastanov.stefan at gmail.com [mailto:krastanov.stefan at gmail.com] On
> Behalf Of Stefan Krastanov
> Sent: Tuesday, July 14, 2015 8:46 PM
> To: cschulte at kth.se
> Cc: users at gecode.org
> Subject: Re: [gecode-users] python binding - Gecode does not find a solution on
> first run, finds a solution on consecutive runs.
> 
> Hopefully you can still help me with the questions about determinism:
> 
> Is the search for solution always exhaustive?
> 
> Can the search give no solutions when there are existing solutions?
> 
> On 14 July 2015 at 14:38, Christian Schulte <cschulte at kth.se> wrote:
> > Please do not ask questions about Gecode bindings. This is about
> > Gecode and we do not maintain these indings (explained on the webpages).
> >
> > Christian
> >
> > --
> > Christian Schulte, www.ict.kth.se/~cschulte/
> >
> >
> >> -----Original Message-----
> >> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On
> >> Behalf Of Stefan Krastanov
> >> Sent: Tuesday, July 14, 2015 8:24 PM
> >> To: users at gecode.org
> >> Subject: [gecode-users] python binding - Gecode does not find a
> >> solution
> > on first
> >> run, finds a solution on consecutive runs.
> >>
> >> Hello,
> >>
> >> I am using:
> >>
> >> gecode-python 0.27
> >> gecode 3.7.3
> >> (newer versions from the debian repository do not work with
> >> gecode-python)
> >>
> >> I have a python function `my_function` that builds a `gecode.space()`
> > object with
> >> around 200 000 linear IRT_NQ constraints and 3 IRT_EQ constraints on
> >> 9 int variables with domain 1-to-10. One final constraint is
> >> `minimize` over the
> > sum of
> >> the variables.
> >>
> >> My python function returns `list(space.search())` at the end.
> >>
> >> The first call to this function usually takes ~1minute and does not
> >> return
> > any
> >> solutions. Consecutive calls take less than a second and return solutions.
> >>
> >> Why is this happening? Is the search non-deterministic?
> >>
> >> Can the search give no solutions when there are existing solutions?
> >>
> >> Why is the first call slow and returns no solutions while consecutive
> > calls are fast
> >> and return solutions? Especially so given that I recreate the space
> >> each
> > time? Is
> >> there some fancy caching happening?
> >>
> >> In any case, thanks for the great software. This is the first time I
> >> am
> > using a
> >> constraint solver and it is quite amazing what it can do.
> >>
> >> Best,
> >> Stefan
> >>
> >> _______________________________________________
> >> Gecode users mailing list
> >> users at gecode.org
> >> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.gecode.org_m
> >> ailman_listinfo_gecode-2Dusers&d=AwICAg&c=-
> dg2m7zWuuDZ0MUcV7Sdqw&r=ag
> >>
> 5oVRuiZInvprFp2PYfMKAexpGCTVWGL34DzpqCiik&m=ooI8YWFt5F7JewPeoyMU
> GhdVf
> >>
> uU8PUgp2eVdX6XslPU&s=RjHJtgLJqMydfeqEGmrbAitzyxKhxgQkswqqaOTNaxE&
> e=
> >