Op 28-02-13 16:16, sanger schreef: Yes Give each entity an extra property: the original value of the planning variable property. For example: class ShiftAssignment { Shift shift; Employee originalEmployee; // Just a normal problem fact Employee employee; // Planning variable } then add a rule which adds a cost for every entity that moved when ShiftAssignment( originalEmployee != employee, $employee : employee) then // add soft constraint for -(employee.getMoveCost()). You can make the move cost depend on all sort of factors.