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Sequencing to minimize the weighted number of tardy jobs. (English) Zbl 0333.68044

Suppose \( n \) jobs are to be processed by a single machine. A fixed processing time \( p_{j} \), a deadline \( d_{j} \) and a weight \( w_{j} \) are associated with each job \( j \). The problem is to find a sequence which minimizes the sum of the weights of tardy jobs. It is shown that if the weighting of the jobs is ”agreeable”, in the sense that \( p_{1}<p_{j} \) implies \( w_{1} \geq w_{j} \), then an optimal sequence can be constructed by an algorithm with \( O(n \log n) \) running time. This provides a common generalization of the case in which all weights are equal, previously solved by J. M. M \( \circ \circ \mathrm{r} e \) [Management Sci., Theory 15, 102-109 (1968; Zbl. 164, 200)] and the case in which all processing times are equal, which is solvable as an assignment problem. The problem of optimally scheduling jobs with equal processing times on \( \mathrm{m} \) identical parallel processors can also be solved by a variant of the same algorithm in \( O(n \log n) \) running time.

MSC:

68Q45 Formal languages and automata
68W99 Algorithms in computer science
68Q25 Analysis of algorithms and problem complexity