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

My previous constraints were necessary, but not sufficient.
They would allow breaking the day into 3 or
more parts with middle parts being too short.

The following are sufficient
to ensure all blocks have at least 4 periods:

X[c,g,p1,d]-X[c,g,p2,d]+X[c,g,p3,d]>=0   for p1< p2< p3<=p1+4, c,g,d...

where periods outside of a day are implictly 0.

Note that the constraints are numerous (quadratic
in the size of a minimum block) and rather loose.

--
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