[gecode-users] Gecode 3.5.0 faster than Gecode 3.7.0?

[Kish Shen]

Hi,

A follow-up: I've found another program (solves the crowded chessboard 
problem, using a "natural" model where each chess piece is modelled with 
a different domain value in a singe board, rather than having a 0/1 
board for each chess pieces). This program uses count with =, and is 20% 
slower in 3.7.0 (compared to 3.5.0).

Since I am getting this slow-down in two different programs, it could 
mean that a count constraint with less than full domain consistency 
could be useful. Does it make sense for Gecode to provide this?

Thanks and cheers,

Kish

On 14/09/2011 13:19, Christian Schulte wrote:
> Okay, you got me red-handed here: before 3.7.0 count was in fact not domain
> consistent for the case
> 	count(x,y,=,z)
> where y is a variable. The pruning for y was actually missing (the values
> for y can only be the values in x provided z>= 1).
>
> So, a bug fix if you wish ;-)
>
> Cheers
> Christian
>
> --
> Christian Schulte, KTH, web.it.kth.se/~cschulte/
>
>
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
> Of Kish Shen
> Sent: Wednesday, September 14, 2011 2:12 PM
> To: users at gecode.org
> Subject: Re: [gecode-users] Gecode 3.5.0 faster than Gecode 3.7.0?
>
> Hi Christian,
>
> Thanks for your reply!
>
> The documentation for both 3.7.0 and 3.5.0 say that the single value count
> constraint achieves domain consistency. I thought you can't really do better
> (more pruning) than domain consistency for single constraints, or am I
> mistaken?
>
> Cheers,
>
> Kish
>
> On 14/09/2011 09:35, Christian Schulte wrote:
>> This is most likely due to the count constraint. In Gecode 3.7.0 it
>> tries to do more pruning and that might cause the slow down (and your
>> examples might not necessarily profit from the additional pruning).
>>
>> Cheers
>> Christian
>>
>> --
>> Christian Schulte, KTH, web.it.kth.se/~cschulte/
>>
>> -----Original Message-----
>> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On
>> Behalf Of Kish Shen
>> Sent: Tuesday, September 13, 2011 6:41 PM
>> To: users at gecode.org
>> Subject: [gecode-users] Gecode 3.5.0 faster than Gecode 3.7.0?
>>
>> Hi,
>>
>> I have just upgrade the ECLiPSe interface to Gecode from Gecode 3.5.0
>> to 3.7.0. As I am currently doing some work on improving the
>> performance of the interface, I have been doing some timings with
>> example programs, and to my surprise, one of the example is running
>> consistently faster with 3.5.0. The run-times are:
>>
>> 3.5.0:        16.34s
>> 3.7.0:        19.99s
>>
>> The only change between these two is the version of Gecode used (plus
>> the changes in the C++ code needed for the upgrade, i.e. the #include
>> for the graph and scheduling modules).
>>
>> As the program is written in ECLiPSe, there is no direct record of the
>> actual Gecode API calls made. The problem is the "roster" example from
>> the ECLiPSe website, modified for use with the Gecode interface. This
>> example is solving a simple rostering problem, and there are a lot of
>> relational constraints posted, plus some boolean expressions, all
>> posted via the MiniModel, and there are also some count contraints
>> (occurrences of one value variant). The search is done in ECLiPSe,
>> i.e. not using the search-engines of Gecode.
>>
>> Is the above information sufficient for even guessing what the slow
>> down might be due to? If not, what additional information might be needed?
>>
>> Cheers,
>>
>> Kish
>>
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Cisco Systems Limited (Company Number: 02558939), is registered in
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