We address a generalization of the classical discrete time-cost tradeoff problem where the costs are irregular and depend on the starting and the completion times of the activities. We present a complete picture of the computational complexity and the approximability of this problem for several natural classes of precedence constraints. We prove that the problem is NP-hard and hard to approximate, even in case the precedence constraints form an interval order. For orders of bounded height, there is a complexity jump: For height one, the problem is polynomially solvable, whereas for height two, it is NP-hard and APX-hard. Finally, the problem is shown to be polynomially solvable for orders of bounded width and for series parallel orders.
|Title of host publication||Algorithms and Computation (Proceedings of the 13th Annual International Symposium, ISAAC'02, Vancouver BC, Canada, September 21-23, 2002)|
|Place of Publication||Berlin|
|Publication status||Published - 2002|
|Name||Lecture Notes in Computer Science|