- Aij : Matrix of days off of the nurse i expressed as a vector of 0 (no day off) and
+1 (day off) for each day j;
- Pij : preferences of the nurse i expressed as
-1 (no work), 0 (no preference) and +1 (work) for each day j (preferences are only related to day and not shifts);
- Djk : demand in nurses on day j and shift k;
- Qik : available shift k for the nurse i;
- T : maximum of days worked by a nurses in
one week;
- c+ : cost of an over-covering;
- c- : cost of an under-covering;
- i : cost of a preference not respected of the
nurse i;
- ik : cost of switching assignment;
- ri : benefit of the respect of the typical schedule of the nurse i (aggregation of
seniority, experiences, skills ...).