Tight approximability of the server allocation problem for real-time applications

Takehiro Ito, Naonori Kakimura, Naoyuki Kamiyama, Yusuke Kobayashi, Yoshio Okamoto, Taichi Shiitada

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)


The server allocation problem is a facility location problem for a distributed processing scheme on a real-time network. In this problem, we are given a set of users and a set of servers. Then, we consider the following communication process between users and servers. First a user sends his/her request to the nearest server. After receiving all the requests from users, the servers share the requests. A user will then receive the data processed from the nearest server. The goal of this problem is to choose a subset of servers so that the total delay of the above process is minimized. In this paper, we prove the following approximability and inapproximability results. We first show that the server allocation problem has no polynomial-time approximation algorithm unless P = NP. However, assuming that the delays satisfy the triangle inequality, we design a polynomial-time 3/2-approximation algorithm. When we assume the triangle inequality only among servers, we propose a polynomial-time 2-approximation algorithm. Both of the algorithms are tight in the sense that we cannot obtain better polynomial-time approximation algorithms unless P = NP. Furthermore, we evaluate the practical performance of our algorithms through computational experiments, and show that our algorithms scale better and produce comparable solutions than the previously proposed method based on integer linear programming.

Original languageEnglish
Title of host publicationAlgorithmic Aspects of Cloud Computing - 3rd International Workshop, ALGOCLOUD 2017, Revised Selected Papers
EditorsAlex Delis, George Pallis, Dan Alistarh
PublisherSpringer Verlag
Number of pages15
ISBN (Print)9783319748740
Publication statusPublished - 2018
Event3rd International Workshop on Algorithmic Aspects of Cloud Computing, ALGOCLOUD 2017 - Vienna, Austria
Duration: Sept 5 2017Sept 5 2017

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume10739 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Other3rd International Workshop on Algorithmic Aspects of Cloud Computing, ALGOCLOUD 2017

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science


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