Interactive timetabling in universities

There are several classes of algorithms which use heuristic methods for constructing school timetables. The first class of algorithms uses graph theoric methods to approximate an exact solution to a variant of the well-known graph colouring problem. The second class uses linear optimization methods to minimize a suitably defined objective function. These algorithms generally create solutions which satisfy a family of constraints but usually cause other problems specific to the institution involved. An algorithm which uses piece-wise incremental construction is described submitting such timetables to be east in interactive mode and allows small perturbations to the specifications without requiring that the program be re-run.