Almost Tight Approximation Hardness and Online Algorithms for Resource Scheduling

Fuente: arXiv
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Autores principales: Das, Rathish, Sun, Hao
Formato: Preprint
Publicado: 2025
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author Das, Rathish
Sun, Hao
author_facet Das, Rathish
Sun, Hao
contents We study the precedence-constrained resource scheduling problem [SICOMP'75]. There are $n$ jobs where each job takes a certain time to finish and has a resource requirement throughout the execution time. There are precedence among the jobs. The problem asks that given a resource budget, schedule the jobs obeying the precedence constraints to minimize makespan (maximum completion time of a job) such that at any point in time, the total resource being used by all the jobs is at most the given resource budget. In the offline setting, an important open question is whether a polynomial-time $O(1)$-factor approximation algorithm can be found. We prove almost tight hardness of approximation: For some constant $α> 0$, there is no $o((\log t_{\max})^α)$-factor ( or $o( ( \log n )^α)$-factor ) approximation algorithm with $n$ jobs of maximum job length $t_{\max}$, unless P = NP ( or NP $\subset$ DTIME$(O( 2^{\text{polylog}(n)}))$ ). We further show a connection between this scheduling problem and a seemingly unrelated problem called the shortest common super-sequence (SCS) problem, which has wide application in Biology and Genomics. We prove that an $o(\log t_{\max})$-factor approximation of the scheduling problem would imply the existence of an $o(|Σ|)$-approximation algorithm for SCS with alphabet $Σ$. We then consider the online setting. We present $Ω(\log n)$ and $Ω(\log t_{\max})$ lower bounds of the competitive ratio of any randomized online algorithm. Moreover, we present a matching $O(\min\{\log n, \log t_{\max}\})$-competitive deterministic online algorithm.
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Almost Tight Approximation Hardness and Online Algorithms for Resource Scheduling
Das, Rathish
Sun, Hao
Data Structures and Algorithms
We study the precedence-constrained resource scheduling problem [SICOMP'75]. There are $n$ jobs where each job takes a certain time to finish and has a resource requirement throughout the execution time. There are precedence among the jobs. The problem asks that given a resource budget, schedule the jobs obeying the precedence constraints to minimize makespan (maximum completion time of a job) such that at any point in time, the total resource being used by all the jobs is at most the given resource budget. In the offline setting, an important open question is whether a polynomial-time $O(1)$-factor approximation algorithm can be found. We prove almost tight hardness of approximation: For some constant $α> 0$, there is no $o((\log t_{\max})^α)$-factor ( or $o( ( \log n )^α)$-factor ) approximation algorithm with $n$ jobs of maximum job length $t_{\max}$, unless P = NP ( or NP $\subset$ DTIME$(O( 2^{\text{polylog}(n)}))$ ). We further show a connection between this scheduling problem and a seemingly unrelated problem called the shortest common super-sequence (SCS) problem, which has wide application in Biology and Genomics. We prove that an $o(\log t_{\max})$-factor approximation of the scheduling problem would imply the existence of an $o(|Σ|)$-approximation algorithm for SCS with alphabet $Σ$. We then consider the online setting. We present $Ω(\log n)$ and $Ω(\log t_{\max})$ lower bounds of the competitive ratio of any randomized online algorithm. Moreover, we present a matching $O(\min\{\log n, \log t_{\max}\})$-competitive deterministic online algorithm.
title Almost Tight Approximation Hardness and Online Algorithms for Resource Scheduling
topic Data Structures and Algorithms
url https://arxiv.org/abs/2509.01086