[gecode-users] print-last patch

Tue Feb 28 20:03:40 CET 2012

No, it does not have it: 3.7.2 is a bug-fix only release (the print-last
thing is a big thing as we rewrote the argument handling completely, that's
why it did not qualify).

Christian

--

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

From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Wajid Hassan
Sent: Tuesday, February 28, 2012 4:39 PM
To: users at gecode.org
Subject: [gecode-users] print-last patch

Hi,

Has the new release 3.7.2 for Windows got this as well? I looked and could
not find it here http://www.gecode.org/doc-latest/reference/PageChange.html

BR/ Wajid

2012/1/18 Christian Schulte <cschulte at kth.se>

Hi,

I added the command line switch -print-last to the trunk. In case you build
Gecode yourself from source you can use the attached patch to get the
behaviour.

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 Josef Eisl

Sent: Tuesday, January 17, 2012 7:02 PM
To: cschulte at kth.se
Cc: users at gecode.org
Subject: Re: [gecode-users] MinimizeScript: Beginners Question

On 01/17/2012 04:59 PM, Christian Schulte wrote:
> Hi Josef,
>
> Thanks for your observations as far as MPG is concerned. I'll think
> them through and look how to improve. The information being spread out
> can't really be helped much as each location takes a different angle
> and different depth. But I promise I'll think...
>
> Then printing each solution is actually what you want (I guess):
> normally, finding a best solution takes so long that you will have to
> settle for the solution that has been found last after the time is up.
> But maybe there could be an additional switch which would only make
> sense in a best solution search scenario: -print-last where only the
> last solution found is printed, and if a time out is encountered then
> also the last and not necessarily best solution is printed. Would that
make you happy?

Yes, such an option would be great :).

Thanks again for your time!

br
Josef

>
> 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 Josef Eisl
> Sent: Tuesday, January 17, 2012 3:52 PM
> To: cschulte at kth.se
> Cc: users at gecode.org
> Subject: Re: [gecode-users] MinimizeScript: Beginners Question
>
> Hello!
>
> On 01/17/2012 02:31 PM, Christian Schulte wrote:
>> Hi,
>>
>> Please let me take your questions in turn.
>>
>> 1. Changing the relation from strict (that is, "<") to a non-strict
>> (that is, "<=") will typically not work. It would entail that you do
>> not only find all _optimal_ solutions but all solution for each and
>> every cost value! So normally that will be way too many solutions!
>> Try it out with Gist on a small example and you will see that this
>> will make
> things break down.
>
> Ups, my bad. Clearly adding a non strict constraint does not make much
> sense.
>
>> Should I add a tip in MPG that the order must be strict for things to
> work?
>
> Maybe, but I my eyes it is more confusing that
> MinimizeSpace/MinimizeScript return non-optimal solutions, at least
> for a new user. Some other things about MPG and optimization that are not
straight forward in my opinion:
>
> 1. Information is spread over several chapters:
>    - 2.5 Best solution search
>    - 3.2 Using a cost function
>    - 6.3 Support for cost-based optimization
>    - 7.4 Search engines
>
> 2. Best Solution Search engine
> It is mentioned in 2.5 and 7.4 but not 3.2 and 6.3 and there are no
> links to the other sections. Maybe it should be stated more clearly
> that BAB or Restart must be used for best solution search.
>
> 3. constrain()
> In 2.5: "Note that every space defines a default constrain() member
> function (to keep the design of models simple). If a model does not
> re-define the
> constrain() member function, the default function will be called which
> throws an exception of type SpaceConstrainUndefined (as this is a
> modeling error)".
> In my eyes the second sentence is not true as OptimizeSpace provides a
> valid constrain().
>
> These are rather beginner problems than problems of MPG. Gecode is one
> of the best documented free software I've seen. I just want to share
> my experience.
>
>> 2. To find all optimal solutions, I would first find _one_ optimal
>> solution as normal. Then I would find all solutions (starting a new
>> search) where the cost value is equal to the optimal const value.
>
> I see. That makes sense.
>
>> 3. You see that printing "all" optimal solutions with respect to 1. and
2.
>> does not really make much sense.
>
> Ok using -solutions for optimal solutions does not work. But how about
> printing only the last (optimal if -solutions 0) solution with
> MinimizeScript?
>
>> I hope that helps
>
> Thank you very much for your quick and detailed answers!
>
> Josef
>
> _______________________________________________
> Gecode users mailing list
> users at gecode.org
> https://www.gecode.org/mailman/listinfo/gecode-users
>
>

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