Originally posted by: umy101

I am trying to solve a problem where I am supposed to schedule teams in a soccer league to play each other. My two decision variables are HomeTeam[Field][Day] and AwayTeam[Field][Day]. They are allowed to take values of a number that corresponds to a team. For example, if there are 16 teams, they can take values 1..16. I am trying to figure out how I can write a constraint so each team only plays each other team once. It does not matter if they are home or away. Any help would be great!

Hi,

you could start with

using CP;

int nbTeam=16;

range Field=1..nbTeam;

range Day=1..100;

tuple game
{
int i;
int j;
}

{game} games= {<i,j> | ordered i,j in Field};

execute
{
games;
}

dvar int dayForGame[games] in Day;
dvar boolean firstPlaysHome[games];

 

subject to
{
forall(f in Field) allDifferent(all(g in games:(g.i==f) || (g.j==f)) dayForGame[g]);

}

int HomeTeam[Field][Day];
int AwayTeam[Field][Day];

execute
{
for(var g in games)
    if (firstPlaysHome[g]==1)
    {
      HomeTeam[g.i][dayForGame[g]]=g.i;    
      AwayTeam[g.i][dayForGame[g]]=g.j;    
    }
    else
    {
      HomeTeam[g.j][dayForGame[g]]=g.j;    
      AwayTeam[g.j][dayForGame[g]]=g.i;    
    }
}

regards