Re: [Help-glpk] var between 2 parameters

[Paolo Tofoni]

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?

Thanks in advance.