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

[Stefan Krastanov]

The question was about gecode, not about the binding. I checked the
manual, but there was no clear listing of searching algorithms with
detailed and structured description.

On 14 July 2015 at 14:54, Christian Schulte <cschulte at kth.se> wrote:
> 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=
>> >
>