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Model Milk
  MODEL MILK
  SET
    oned={11..21},
    alld={1..10},
    farm={1..21},
    days={1..2},
    ! sets to eliminate subtours at 2nd stage
    sa={6,7,20},
    sb={2,5,18},
    sc={3,4,13,16,19},
    ! sets to eliminate subtours at 3rd stage
    sd={8,9,21},
 

 

 se={1,2,6,7,10,17};
  DATA
    Dist[farm,farm] << "farm21.dat",
    Cap[farm] << "cap21.dat",
    Tcap = 80;
    capacity (1000 litres)
  VARIABLES
 

 

 x[farm,farm,days] integer,
 

 

 y[oned,days] integer;
  OBJECTIVE
 

 

 MINIMIZE cost=sum{i in farm, j in farm, k in days,i < j} Dist[i,j]*x[i,j,k];
  CONSTRAINTS
 

 

 limit{k in days} : sum{i in oned} Cap[i]*y[i,k] <= Tcap - sum{i in alld} Cap[i],
 

 

 dayvis{i in oned} : sum{k in days} y[i,k] = 1,
 

 

 mat{i in alld, k in days} : sum{j in farm, j > i} x[i,j,k] +sum{j in farm, j < i} x[j,i,k] = 2,
 

 

 mat{i in oned, k in days} : sum{j in farm, j > i} x[i,j,k] +sum{j in farm, j < i} x[j,i,k] = 2*y[i,k],
 

 

 va{i in oned, j in farm,k in days, j > i} : x[i,j,k] <= y[i,k],
 

 

 vb{i in oned, j in farm,k in days, j < i} : x[j,i,k] <= y[i,k],
 

 

 suba{k in {1..2}} : sum{i in sa,j in sa,i < j} x[i,j,k] <= 2,
 

 

 subb{k in {1..2}} : sum{i in sb,j in sb,i < j} x[i,j,k] <= 2,
 

 

 subc{k in {1..2}} : sum{i in sc,j in sc,i < j} x[i,j,k] <= 4,
 

 

 subd{k in {1..2}} : sum{i in sd,j in sd,i < j} x[i,j,k] <= 2,
 

 

 sube{k in {1..2}} : sum{i in se,j in se,i < j} x[i,j,k] <= 5,
 

 

 bounds{i in farm, j in farm, k in days,i < j} : x[i,j,k] <= 1,
 

 

bounds{i in {12..21},k in days} : y[i,k] <= 1,
 

 

 bounds{i in {11..11}, k in {1..1}} : y[i,k] = 1,
 

 

 bounds{i in {11..11}, k in {2..2}} : y[i,k] = 0;
  END MODEL
   

solve MILK;
   

print solution for MILK >> "milk.sol";
   

quit;

  cap21.dat
    [0,5,4,3,6,7,3,4,6,5,4,7,3,4,5,6,8,5,7,6,6]
  farm21.dat
    [0.0, 4.2,11.0, 8.1,10.3, 5.4, 8.1, 6.0, 6.7, 3.2, 6.0, 7.2, 5.4, 8.2,11.7, 8.1, 3.2, 7.8, 9.2, 7.8, 6.4,
    0.0, 0.0, 8.9, 8.1, 6.3, 5.4,10.0, 9.5,10.8, 6.3, 9.5, 9.1, 5.4, 5.1,11.4, 6.4, 2.0, 3.6, 7.8, 8.5,10.6,
    0.0, 0.0, 0.0, 5.0, 6.3,14.3,18.7,12.1,17.1,14.1,17.0, 8.6, 6.1, 4.2, 5.1, 3.0,10.8, 9.2, 2.2,17.5,15.5,
    0.0, 0.0, 0.0, 0.0, 9.2,12.7,16.1, 7.3,13.0,11.2,13.6, 3.6, 2.8, 6.1, 3.6, 3.2, 9.2,10.2, 2.8,15.6,11.0,
    0.0, 0.0, 0.0, 0.0, 0.0,11.0,16.0,14.2,17.0,12.6,15.8,12.1, 8.1, 3.2,11.0, 6.1, 8.2, 4.1, 7.0,14.0,16.4,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.1,11.2, 8.9, 4.1, 6.4,12.5, 9.9,10.4,16.3,11.7, 3.6, 7.1,13.0, 3.2,10.2,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,12.2, 7.1, 5.0, 4.1,14.9,13.4,15.1,19.7,15.8, 8.1,12.2,17.1, 2.8, 9.5,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 6.7, 7.6, 8.5, 4.0, 6.4,11.3,10.0, 9.4, 9.1,13.0, 9.8,13.0, 4.1,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0, 3.0,10.4,11.0,14.9,16.3,14.1, 9.2,14.2,15.0, 9.1, 2.8,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 3.2, 9.9, 8.5,11.0,14.8,11.2, 4.5, 9.4,12.4, 5.4, 6.1,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,11.7,11.2,14.1,17.1,14.0, 7.6,12.5,15.1, 6.1, 5.4,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.1, 8.9, 6.0, 6.4, 9.5,12.0, 6.4,15.0, 8.1,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0, 6.4, 3.2, 6.4, 8.0, 4.0,12.8, 9.5,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 8.2, 3.0, 7.1, 5.0, 4.1,13.6,13.9,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.4,12.7,13.0, 4.1,19.2,14.0,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 8.1, 7.6, 1.4,14.8,12.6,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0, 9.4, 6.7, 9.4,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 8.9,10.0,14.2,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,16.1,13.3,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,11.0,
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

 

 

 

 

 

 

 

  
         
 
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