Hello Daniele,
take a look at this constraint:
/* temporal precedence constraint */
subject to PrecTemp{i in A,j in A}: sum{t in T} tt[t]*x[j,t] >= sum{t in T} tt[t]*x[i,t] + d[i];
For i = j it requires non-positive durations 0 >= d[i].
Best regards
Xypron
-------- Original-Nachricht --------
> Datum: Fri, 6 Jul 2012 12:25:58 +0200
> Von: Daniele Micarelli <address@hidden>
> An: address@hidden
> Betreff: [Help-glpk] Problem Has no Primal Feasible Solution
> Hi,
> i'm attaching the two file .mod and .dat to let you know
>
> When i run these files with glpsol, i get these two messages at the end:
>
> *Model has been successfully generated
> and
> PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION
>
> *in my opinion should exist one solution
>
> it's possible?