Re: [eclipse-clp-users] Performance-related issues in heuristic optimization with ECLiPSe

From: Soheil Samii <sohsa_at_...107...>
Date: Thu, 19 Jun 2008 20:05:38 +0200

I just would like to thank you for all replies on this issue. I have used the 
suggestions and I experience now smaller runtimes for the incomplete search. 
Of course, I have a lot of more experimentation to do. For the complete 
search, it seems to take long time for a scheduling problem with 50 tasks. Of 
course, this is expected since the problem is NP-complete.



On Wednesday 18 June 2008 01:25:23 pm Kish Shen wrote:
> Hi,
> Just adding some ECLiPSe specific points:
> Soheil Samii wrote:
> > 3. The order of the constraints is important.
> As Marco said, the order of posting the constraints is probably not very
>   important. However, the order of propagation from the constraints can
> be important, because it can affect the amount of computation done
> during the propagation, but it is rather tricky to really understand and
> reason about this, and most systems do not provide the user with much
> control over the order of propagation anyway. ECLiPSe does provide some
> control over this with the priority system for execution, but it is a
> rather blunt tool: normally you will use the priority system to give
> constraints that have costly propagation low priority, so that it only
> execute after other `cheap' constraints have done their job.
> > Regarding the cumulative/4 constraint: Is it better to use the version in
> > ic_cumulative or is it better to use the one in ic_edge_finder3? Which
> > one is best from the point of view of runtime?
> The idea of providing the same constraints in the different libraries is
> to allow you to swap one library for another by just changing one line
> (the line that loads in the library, e.g. :- lib(ic_edge_finder3)), so
> that you can see which library works best for you. One more point to
> add: I think the main algorithm for the edge-finders are implemented in
> C, while cummulative is implemented in ECLiPSe.
> Cheers,
> Kish
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Received on Thu Jun 19 2008 - 11:04:09 CEST

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