We consider the total weighted completion time scheduling problem for parallel identical machines and precedence constraints, P jprecj PwiCi. This important and broad class of problems is known to be NP-hard, even for restricted special cases, and the best known approximation algorithms have worstcase performance that is far from optimal. However, little is known about the experimental behavior of algorithms for the general problem. This paper represents the rst attempt to comprehensively describe and evaluate a range of weighted completion time scheduling algorithms. We rst describe a family of combinatorial scheduling algorithms that optimally solve the single machine problem, and show that they can be used to achieve good performance for the multiple machine problem. These algorithms are e cient and nd schedules that are on average within 1:5 of optimal over a large synthetic benchmark consisting of trees, chains, and instances with no precedence constraints. We then present severa...
Ivan D. Baev, Waleed Meleis, Alexandre E. Eichenbe