> I follow your suggestions and I considered the following situation:
>
>
> var check_t1 {(m,k) in FERMI, (j,p,m) in V_TECNOLOGICI } binary;
> param BigP := max {(j,p) in FERMI} fine_fermo[j,p];
>
>
> s.t. k2 {(m,k) in FERMI, (j,p,m) in V_TECNOLOGICI}:
> inizio_fermo[m,k] <= start[j,p,m] + BigP * check_t1[m,k,j,p];
>
> s.t. k3 {(m,k) in FERMI, (j,p,m) in V_TECNOLOGICI}:
> (start[j,p,m] + lt[j,p,m]) - BigP * check_t1[m,k,j,p]<=
> inizio_fermo[m,k];
>
> where
>
> start[j,p,m], lt[j,p,m]) are vars and inizio_fermo[m,k] are parmas.
>
> I always obtain all vars set to 0 and the reponse:
>
> OPTIMAL SOLUTION FOUND
> Integer optimization begins...
> Gomory's cuts enabled
> MIR cuts enabled
> Cover cuts enabled
> Clique cuts enabled
> Creating the conflict graph...
> The conflict graph has 2*5 vertices and 9 edges
> + 445: mip = not found yet >= -inf
> (1; 0)
> Warning: numerical instability (dual simplex, phase II)
> Warning: numerical instability (dual simplex, phase II)
> Cuts on level 0: gmi = 1; mir = 36; cov = 2;
> Cuts on level 0: mir = 36; cov = 2;
> Cuts on level 0: mir = 36; cov = 2;
> + 620: mip = not found yet >= tree is empty
> (0; 1)
> PROBLEM HAS NO INTEGER FEASIBLE SOLUTION
>
> but it's not the best solution ... what can I do to solve the issue?
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