Re: [Help-glpk] Tricky constraint formulation

[Andrew Makhorin]

On Wed, 2011-03-09 at 18:43 +0300, Andrew Makhorin wrote:
> On Wed, 2011-03-09 at 06:30 -0800, teitifeiti wrote:
> > Hello everyone. 
> > 
> > I have a problem in formulating a constraint. The constraint is:
> >  C[r,i] - C[r,k] + P*D[i,k] >= T[r,i]    where    (1 <= r <= M ; 1 <= i < k
> > <= N);
> > 
> > So what I tried first was: 
> > 
> > s.t. constraint{r in 1..R,i 1..I,k in 1..I}
> > 
> > But that constraint holds for all k < i, which I don't want it to do. 
> > 
> > Does anyone have a cool solution to my problem??
> > 
> > Respectfully, TeitiFeiti
> 
> s.t. constraint{r in 1..R,i 1..I,k in 1..I: i < k} ...
> 

The following is more efficient:

s.t. constraint{r in 1..R,i 1..I,k in i+1..I} ...