Re: [Help-glpk] Newbie scheduling problem question, contiguous time interval constraints

[Michael Hennebry]

On Wed, 29 May 2013, Roland Roberts wrote:

> On 05/29/2013 01:27 PM, Michael Hennebry wrote:
> > On Tue, 28 May 2013, Roland Roberts wrote:
> >
> > > The basic problem is that I classes c, student groups g, time periods p, 
> > > and days d. We're breaking each day into 15-minute "modules" which have to 
> > > be schedule. A class has to span 3-8 modules on any give day. Some classes 
> > > have a minimum number of modules per week that have to be completed. With 
> > > just the above, I can specify the constraints by thinking of this as a 
> > > 4-dimensional array X[c,g,p,d] and the constraints are various sums. The 
> > > problem I run into is specifying the the continuity constraint on 
> > > scheduling. It's not sufficient to have 3 modules for class C1, they have 
> > > to be 3 contiguous modules.
> > >
> > > How do I specify this sort of thing?
> >
> > Is each class a fixed length?
>
> No, that's the first thing the school wants to relax with the modular 
> scheduling. Even now, a few classes hold a weekly "double-period" but 
> everything is hand scheduled which basically works by severely limiting what 
> is offered to students. The attempt this past year to hand schedule under the 
> new paradigm was a failure as hand scheduling never resolved the conflicts 
> that we kept running into.

To require every selected period be in a block of 4:

 p+3
 SUM X[c,g,j,d] >= 4*x[c,g,p,d]   for c,g,p,d ...
j=p-3

I've neglected the beginnings and ends of the days.

--
Michael   address@hidden
"On Monday, I'm gonna have to tell my kindergarten class,
whom I teach not to run with scissors,
that my fiance ran me through with a broadsword."  --  Lily