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

[Roberto Castañeda Lozano]

Hi Andrea, you are right, the check is there because I wrote the code 
some time ago and it was required then. You can remove it and everything 
should work just fine.

Best regards,

Roberto

On 11/20/2013 07:51 PM, Andrea Peano wrote:
> 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 
> <mailto: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 <mailto: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
>         <mailto:users-bounces at gecode.org> [users-bounces at gecode.org
>         <mailto:users-bounces at gecode.org>] on behalf of Andrea Peano
>         [andrea.peano at unife.it <mailto:andrea.peano at unife.it>]
>         Sent: Thursday, October 31, 2013 12:50
>         To: Christian Schulte
>         Cc: users at gecode.org <mailto: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 <mailto: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/ <http://www.ict.kth.se/%7Ecschulte/>
>
>
>         From:
>
>         users-bounces at gecode.org <mailto:users-bounces at gecode.org>
>         [mailto: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 <mailto: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 <tel:%2B39%200532%2097%204827>
>
>
>
>
>
>
>
>     -- 
>
>     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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