2026-08-15T23:25:11Z https://drops.dagstuhl.de/oai

oai:drops-oai.dagstuhl.de:7457 2024-03-06T10:40:19Z ddc:004 open_access

A QPTAS for the General Scheduling Problem with Identical Release Dates Antoniadis, Antonios Hoeksma, Ruben Meißner, Julie Verschae, José Wiese, Andreas Generalized Scheduling QPTAS Unsplittable Flows The General Scheduling Problem (GSP) generalizes scheduling problems with sum of cost objectives such as weighted flow time and weighted tardiness. Given a set of jobs with processing times, release dates, and job dependent cost functions, we seek to find a minimum cost preemptive schedule on a single machine. The best known algorithm for this problem and also for weighted flow time/tardiness is an O(loglog P)-approximation (where P denotes the range of the job processing times), while the best lower bound shows only strong NP-hardness. When release dates are identical there is also a gap: the problem remains strongly NP-hard and the best known approximation algorithm has a ratio of e+\epsilon (running in quasi-polynomial time). We reduce the latter gap by giving a QPTAS if the numbers in the input are quasi-polynomially bounded, ruling out the existence of an APX-hardness proof unless NP\subseteq DTIME(2^polylog(n)). Our techniques are based on the QPTAS known for the UFP-Cover problem, a particular case of GSP where we must pick a subset of intervals (jobs) on the real line with associated heights and costs. If an interval is selected, its height will help cover a given demand on any point contained within the interval. We reduce our problem to a generalization of UFP-Cover and use a sophisticated divide-and-conquer procedure with interdependent non-symmetric subproblems. We also present a pseudo-polynomial time approximation scheme for two variants of UFP-Cover. For the case of agreeable intervals we give an algorithm based on a new dynamic programming approach which might be useful for other problems of this type. The second one is a resource augmentation setting where we are allowed to slightly enlarge each interval. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Antonios Antoniadis and Ruben Hoeksma and Julie Meißner and José Verschae and Andreas Wiese 2017 Is Part Of LIPIcs, Volume 80, 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.ICALP.2017.31 urn:nbn:de:0030-drops-74575 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2017.31 eng https://creativecommons.org/licenses/by/3.0/legalcode