[gecode-users] Unary: Allow for negative durations when task is not mandatory

[Andrea Peano]

Hello,
your code was very useful.

I've just seen that new implementations of standard nooverlap don't check
anymore for multiple occurrences of the same variable within the same array
(e.g., x0.same(home)). Am I right? Instead, your propagator still checks it.
I think this limitation might be too restrictive... But I cannot say
whether it is actually required or not.
What do you think about that?

Thank you,
Andrea





On Fri, Nov 1, 2013 at 3:14 PM, Andrea Peano <andrea.peano at unife.it> wrote:

> Hi Roberto,
> thank you very much. I'm pretty sure that it's close enough to my needs!
>
> I'll try it asap :)
>
> Thanks,
> Andrea
>
>
> On Fri, Nov 1, 2013 at 9:45 AM, Roberto Castaneda Lozano <rcas at kth.se>wrote:
>
>> Hi Andrea,
>>
>> Interestingly enough I implemented for my own purposes a similar
>> generalization to nooverlap a year ago, see the attachment.
>>
>> Best regards,
>>
>> Roberto
>>
>> From: users-bounces at gecode.org [users-bounces at gecode.org] on behalf of
>> Andrea Peano [andrea.peano at unife.it]
>> Sent: Thursday, October 31, 2013 12:50
>> To: Christian Schulte
>> Cc: users at gecode.org
>> Subject: Re: [gecode-users] Unary: Allow for negative durations when task
>> is not mandatory
>>
>> Yes, sure it's useful, thank you.
>> I'm just wondering whether a modification of the unary might be more
>> efficient or not.
>> In such a case, I could modify the source files of Gecode, by adding
>> another (modified) unary constraint, otherwise... should I write an
>> user-defined propagator?
>>
>> I've the same doubt regarding the nooverlap, I'd like to achieve a
>> generalization of it.
>> In this generalization rectangles of the same "group" can overlap
>> eachother, but they cannot overlap other rectangles of other groups.
>> So the new nooverlap will take in input an IntArgs array which contains
>> the group IDs.
>>
>> In your guide I read:
>> "The constraints [nooverlap] are implemented by a naive propagator
>> (considering pairwise no-
>> overlap between rectangles including constructive disjunction, see also
>> GCCAT: diffn),
>> this will change in the future. "
>>
>> I could add a condition within the implementation of the nooverlap, that
>> checks if the two rectangles belong to two different groups. Is it right?
>>
>> Do you have any suggestion?
>>
>> Thank you,
>> Andrea
>>
>> On Wed, Oct 30, 2013 at 1:05 PM, Christian Schulte
>> <cschulte at kth.se> wrote:
>>
>> Hi,
>>
>> There is a generic trick for situations like this: you introduce new
>> variables tend', tstart' and tdur' and only enforce that they are equal to
>> tend, tstart,
>>  tdur respectively when the Boolean variable is 1. That means if the
>> Boolean variable is 0, the new variables can have whatever value.
>>
>> Hope that helps
>> Christian
>>
>> --
>> Christian Schulte, Professor of Computer Science, KTH,
>>
>> www.ict.kth.se/~cschulte/
>>
>>
>> From:
>>
>> users-bounces at gecode.org [mailto:users-bounces at gecode.org]
>> On Behalf Of Andrea Peano
>>
>> Sent: Tuesday, October 29, 2013 10:21 AM
>>
>> To:
>> users at gecode.org
>>
>> Subject: [gecode-users] Unary: Allow for negative durations when task is
>> not mandatory
>>
>>
>> Hello all,
>>
>> I would modify the unary constraint in order to allow negative durations
>> (tend<tstart) when the boolvar m (mandatory) is 0.
>>
>> Is there an easy way to do this?
>>
>> Thank you,
>>
>> Andrea
>>
>> --
>>
>>
>>
>>
>> Andrea Peano - PhD student
>>
>>
>> Department of Engineering - University of Ferrara
>> Tel: +39 0532 97 4827
>>
>>
>>
>>
>>
>
>
> --
>
> Andrea Peano - PhD student
> Department of Engineering - University of Ferrara
> Tel: +39 0532 97 4827
>



-- 

Andrea Peano - PhD student
Department of Engineering - University of Ferrara
Tel: +39 0532 97 4827
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