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arXiv 1612.03339cs.DS
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最小和单机排序问题的一种原始-对偶近似算法

A Primal-Dual Approximation Algorithm for Min-Sum Single-Machine Scheduling Problems

Maurice Cheung, Julián Mestre, David B. Shmoys, José Verschae

摘要:

我们考虑下面的单机调度问题,它通常表示为$1||\sum f_{j}$:我们给出了$n$作业调度在一台机器上,其中每个作业$j$有一个完整的处理时间$p_j$,并有一个非减,非负的成本函数$f_j(C_{j})$,指定的成本完成$j$在时间$C_{j}$ ;目标是最小化$\sum_{j=1}^n f_j(C_j)$。Bansal \& Pruhs最近给出了性能保证为16的第一常数近似算法。我们改进了这个结果,给出了一个原始-对偶伪多项式时间算法的基础上最近推出的背包覆盖不等式。该算法找到一个时间表的成本最多四倍的构造的对偶解决方案。虽然我们表明,这个界是紧的,我们的算法,我们留下开放的问题,是否完整性差距的LP小于4。最后,我们将展示如何适应的技术,以产生任何$ε>0$,一个$(4+ε)$近似算法这个问题。

英文摘要:

We consider the following single-machine scheduling problem, which is often denoted $1||\sum f_{j}$: we are given $n$ jobs to be scheduled on a single machine, where each job $j$ has an integral processing time $p_j$, and there is a nondecreasing, nonnegative cost function $f_j(C_{j})$ that specifies the cost of finishing $j$ at time $C_{j}$; the objective is to minimize $\sum_{j=1}^n f_j(C_j)$. Bansal \& Pruhs recently gave the first constant approximation algorithm with a performance guarantee of 16. We improve on this result by giving a primal-dual pseudo-polynomial-time algorithm based on the recently introduced knapsack-cover inequalities. The algorithm finds a schedule of cost at most four times the constructed dual solution. Although we show that this bound is tight for our algorithm, we leave open the question of whether the integrality gap of the LP is less than 4. Finally, we show how the technique can be adapted to yield, for any $ε>0$, a $(4+ε)$-approximation algorithm for this problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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