Originally posted by: Guerlain

Good Morning

I want to solve an IRP with cplex and I wrote this model but it don't give solutions 

My Inventory Problem and VRP separately gives right solutions but when I combined them together they don't give no mistakes and no solution too

can you help me to let it works and thanks

Hi,

can you attach your .dat so that other users can help ?

regards

Originally posted by: Guerlain

Hi

of corse ​ you can find the files in the attachment

I progressed in my work and I think the problem is in the constraint of vehicle capacity :

forall(i in 2..n, k in Vehicles, t in 1..t)  
sum(i in 2..n)Transf[i][k][t] <= sum(k in Vehicles)Cap_Veh[k][t]*y[1][k][t];

if anyone can help me to solve this and Thanks

Hi,

if you label some of your constraints such as:

forall(j in 2..n, k in Vehicles,t in 1..t)
ct1:sum(i in cities: j!=i)  x[<i,j>][k][t]==y[j][k][t];

forall(i in 2..n, k in Vehicles,t in 1..t)
ct2:sum(j in cities: j!=i)  x[<i,j>][k][t]==y[i][k][t];

forall(i,j in 2..n: j!=i, k in Vehicles, t in 1..t)
ct3:u[i][k][t]- u[j][k][t]+(sum(k in Vehicles)Cap_Veh[k][t]* x[<i,j>][k][t])<= sum(k in Vehicles)Cap_Veh[k][t] - Transf[j][k][t];
 
forall(i in 2..n, k in Vehicles, t in 1..t)
ct4:Cap_Veh[k][t] <= u[i][k][t] <= sum(k in Vehicles)Cap_Veh[k][t];

// Vehicle Constraints

forall(i in 2..n, k in Vehicles, t in 1..t)   
ct5:sum(i in 2..n)Transf[i][k][t] <= sum(k in Vehicles)Cap_Veh[k][t]*y[1][k][t];

forall(i in cities, k in Vehicles, t in 1..t)
ct6:Cap_Veh[k][t]*y[i][k][t]<=stock[1][t];

then you ll get a relaxed solution and some relaxations and conflicts that will help you spot issues

regards