Solutions not satisfying some constraints

Question

I wanna solve a simple integer programming problem for scheduling with IBM ILOG CPLEX and my whole code is below.

Under specific data, the solution with objective 11,306 is found but some solutions don't satisfy specific constraint, ct2. I wonder if CPLEX is considered an optimal solution even if it does not satisfy some constraints, or is there a problem with my coding? If you need I can send you the data. I wanted to attach the data on this post but couldn't find a way.

Really hope I can get some answer here.

int NbGroup = ...;
int NbAutoclave = ...;
int NbTimeslot = ...;
range Group = 1..NbGroup;
range Autoclave = 1..NbAutoclave;
range Timeslot = 1..NbTimeslot;
int MonthlyProduct[Group] = ...;
int CycleTime[Group][Timeslot] = ...;
int CureTime[Group] = ...;
int Compatibility[Group][Autoclave] = ...;



dvar int Assign[Group][Autoclave][Timeslot] in 0..1;


minimize
  sum( g in Group, a in Autoclave, t in Timeslot ) t * Assign[g][a][t];



subject to {


forall (g in Group)
  ct1:
    sum( a in Autoclave, t in Timeslot ) 
        Compatibility[g][a] * Assign[g][a][t] == MonthlyProduct[g]; 


forall (g in Group)
forall (t in 1..NbTimeslot:t in (1..NbTimeslot-CycleTime[g][t]+1))
  ct2:
    sum( a in Autoclave, cy in 1..CycleTime[g][t] )
        Compatibility[g][a] * Assign[g][a][t+cy-1] <= 1;                  


forall( a in Autoclave, t in Timeslot )
  ct3:
    sum( g in Group, cu in 1..CureTime[g]: t-cu+1 in Timeslot)
        Compatibility[g][a] * Assign[g][a][t-cu+1] <= 1; 


  ct4:
    sum( g in Group, a in 1..1, t in 1..7 ) 
        Assign[g][a][t] == 0;

  ct5:
    sum( g in Group, a in 2..2, t in 1..6 ) 
        Assign[g][a][t] == 0;


//to fix some solutions

Assign[9][1][23]==1;
Assign[9][1][95]==1;
Assign[9][1][143]==1;
Assign[9][1][167]==1;
Assign[9][1][239]==1;
Assign[9][1][287]==1;
Assign[9][1][311]==1;


}


tuple SolutionT{ 
    int a;
    int b;
    int c;
    int d; 
};
{SolutionT} Solution = {<a0,b0,c0,Assign[a0][b0][c0]> | a0 in Group, b0 in Autoclave, c0 in Timeslot};
execute{ 
    writeln(Solution);
}

Answer 1

Same question at https://community.ibm.com/community/user/datascience/communities/community-home/digestviewer/viewthread?GroupId=5557&MID=87626&CommunityKey=ab7de0fd-6f43-47a9-8261-33578a231bb7&tab=digestviewer

And some answer there