system :=
{
	schooltypes   : list of schooltype;
};

schooltype :=
{
  schools : list of school;
};

school :=
{
  lteacher : list of teacher
           := updateref(lteacher_1,friend(teacher.position)); 
  sexratio : real    /* sex=0: male, sex=1: female! */
           := haselements(lteacher.sex,1) / length(lteacher);
  sexlist  : list of real := append(sexlist_1, sexratio);
  prob1    : real 
           := ny * exp(kappa * sexratio_1);    
};

teacher :=
{
  position :  list of school;
  sex      :  int;
  age      :  int 
           := age_1 + 1;
  duration :  int 
           := (normal(1,15,5) if sex else normal(1,30,5))
              if count = 1 else
              duration_1 - 1;
  cond     :  int 
           := 1 if (duration_1 = 1) || (age_1 >= 64) else 0;
  death    :  list of teacher
           := delete(self(teacher), 
	             self(teacher) if cond_2 else []);
  new      :  list of teacher
           := copy(self(teacher), 
                   cond_1, 
                   [age_1      :: uniform(1,25,30),
                    cond_1     :: 0,
                    cond_2     :: 0,
                    sex        :: 1 if prob(1,position.prob1_1) 
		                    else 0,
                    duration_1 :: normal(2,15,5) 
                                  if sex else 
                                  normal(2,30,5)      
                   ]);
};