Colijn, A.W.2008-02-262008-02-261981-03-01http://hdl.handle.net/1880/45462Necessary and sufficient conditions are presented for the existence of a solution to the extended school time-tabling problem, in which each class (or year-group) and each teacher (or teaching department) is available more than once during each period, and in which pre-assignments may occur. An algorithm for constructing time-tables follows naturally from the proof of the result.(1)EngComputer Scienceunknown1981-62-1410.11575/PRISM/30567