Originally posted by: NguyenHuuTRi

 

Hi,

I am trying to code the following syntax in my model. However, I got the trouble with if conditions which make my model can not run:

the coding is:

forall ( t in timeslot, g in group){
if (t>=2) (cs[g][t]-1); 
else (cs[g][t]-0);
};

 

 

Appreciate it if you could help me resolve this issue.

 

Thanks.

 

 

 

range type = 1..3;
range course = 1..59; 
range room = 1..14;
range lecture = 1..18;
range timeslot = 1..12;
range group=1..13;
int lecturetimea[lecture][timeslot] = ...;
int courselecturea[course][lecture]=...;
int courserooma[course][room]=...;
int caparooma[type]= ...;
int capa_cg[group]=...;
int coursegroupa[course][group]=...;

 

tuple lecture_time { 
    int lecture; 
    int time; 
}; 
setof (lecture_time) LectureTimes = 
        {<l,t> | l in lecture,t in timeslot : lecturetimea[l][t]==1};

tuple course_room { 
    int course; 
    int room; 
}; 
setof (course_room) CourseRooms = 
        {<c,r> | c in course,r in room : courserooma[c][r]==1};

tuple course_lecture { 
    int course; 
    int lecture;     
}; 
setof (course_lecture) CourseLectures = 
        {<c,l> | c in course, l in lecture : courselecturea[c][l]==1};

tuple course_type{
    int idcourse;
    int idtype;
};
setof (course_type) coursetypesa = ...;

tuple course_group { 
    int idcourse; 
    int idgroup; 
};

setof (course_group) CourseGroups = {<c,g> | c in course, g in group: coursegroupa[c][g]==1};

tuple lecture_course_time {
    int lecture;
    int course;
    int type;
    int time;
    int room;

}
setof (lecture_course_time) LectureCourseTimes = 
        {<l,c,ty,t,r> | <c,l> in CourseLectures, <l,t> in LectureTimes , <c,ty> in coursetypesa, <c,r> in CourseRooms};
    

//sorted {lecture_course_time} s={<l,c,ty,t,r> |<c,l> in CourseLectures, <l,t> in LectureTimes , <c,ty> in coursetypesa, <c,r> in CourseRooms};

 

dvar boolean x[LectureCourseTimes];
dvar boolean cs[group][timeslot];
//dvar boolean csa[group][timeslot];
dvar boolean f[group][timeslot];

//dexpr int f[g][t] =   sum(g in group, t in timeslot:t<=11)(cs[g][t]*(cs[g][t+1]-cs[g][t]));

//maximize sum (w in LectureCourseTimes) x[w];

minimize 
sum(t in timeslot, g in group)f[g][t];

subject to
{ 

forall (g in group){
sum(t in timeslot)cs[g][t]==capa_cg[g];
}

forall (<l,t> in LectureTimes) {
        assignLecture :    sum(<l,c,ty,t,r> in LectureCourseTimes) x[<l,c,ty,t,r>] <=1;

    };        

forall (c in course) {
        asignCourse: sum(<l,c,ty,t,r> in LectureCourseTimes) x[<l,c,ty,t,r>]<= 1 ; 
    };    
    
    
    forall (r in room, t in timeslot){ 
    assignRoom: sum(<l,c,ty,t,r> in LectureCourseTimes)x[<l,c,ty,t,r>]<=1;
};

forall (t in timeslot, ty in type) {
        asignCapaRoomType: sum(<l,c,ty,t,r> in LectureCourseTimes) x[<l,c,ty,t,r>]<= caparooma[ty]; 
    };

forall(t in timeslot, g in group){
sum(<l,c,ty,t,r> in LectureCourseTimes)x[<l,c,ty,t,r>]*coursegroupa[c][g]==cs[g][t];
};

 

forall ( t in timeslot:t<=11, g in group){
-cs[g][t]+ cs[g][t+1]<=f[g][t];
};

forall ( t in timeslot, g in group){
if (t>=2) (cs[g][t]-1); 
else (cs[g][t]-0);
};

 

forall(t in timeslot, g in group){
sum(<l,c,ty,t,r> in LectureCourseTimes)x[<l,c,ty,t,r>]*coursegroupa[c][g]<=1;
};

};

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi

(cs[g][t]-1); 

is not a constraint.

Can you try with

(cs[g][t]-1)==0;

instead ?

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: NguyenHuuTRi

Hi,

I am trying using the another if condition but it can not work as cs[g][t] is a decision varaiable. Is there anyway to rewrite this one?

forall ( t in timeslot:t==1, g in group){
if (cs[g][t]==0) f[g][t]==(cs[g][t]- cs[g][t-1])-1 ; 
else (f[g][t]==cs[g][t]- cs[g][t-1]);
};

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

you could use logical constraints:

forall ( t in timeslot:t==1, g in group){
 (cs[g][t]==0) => (f[g][t]==(cs[g][t]- cs[g][t-1])-1) ;
 (cs[g][t]!=0) => (f[g][t]==cs[g][t]- cs[g][t-1]);
};

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer