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DOI: 10.4230/OASIcs.ATMOS.2023.10

Submodularity Property for Facility Locations of Dynamic Flow Networks

Authors: Peerawit Suriya, Vorapong Suppakitpaisarn, Supanut Chaidee, and Phapaengmueng Sukkasem

Published in: OASIcs, Volume 115, 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)

Abstract

This paper considers facility location problems within dynamic flow networks, shifting the focus from minimizing evacuation time to handling situations with a constrained evacuation timeframe. Our study sets two main goals: 1) Determining a fixed-size set of locations that can maximize the number of evacuees, and 2) Identifying the smallest set of locations capable of accommodating all evacuees within the time constraint. We introduce flow_t(S) to represent the number of evacuees for given locations S within a fixed time limit t. We prove that flow_t functions is a monotone submodular function, which allows us to apply an approximation algorithm specifically designed for maximizing such functions with size restrictions. For the second objective, we implement an approximation algorithm tailored to solving the submodular cover problem. We conduct experiments on the real datasets of Chiang Mai, and demonstrate that the approximation algorithms give solutions which are close to optimal for all of the experiments we have conducted.

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Peerawit Suriya, Vorapong Suppakitpaisarn, Supanut Chaidee, and Phapaengmueng Sukkasem. Submodularity Property for Facility Locations of Dynamic Flow Networks. In 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023). Open Access Series in Informatics (OASIcs), Volume 115, pp. 10:1-10:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{suriya_et_al:OASIcs.ATMOS.2023.10,
  author =	{Suriya, Peerawit and Suppakitpaisarn, Vorapong and Chaidee, Supanut and Sukkasem, Phapaengmueng},
  title =	{{Submodularity Property for Facility Locations of Dynamic Flow Networks}},
  booktitle =	{23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)},
  pages =	{10:1--10:13},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-302-7},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{115},
  editor =	{Frigioni, Daniele and Schiewe, Philine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2023.10},
  URN =		{urn:nbn:de:0030-drops-187711},
  doi =		{10.4230/OASIcs.ATMOS.2023.10},
  annote =	{Keywords: Approximation Algorithms, Dynamic Networks, Facility Location, Submodular Function Optimization}
}

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PACE Solver Description

DOI: 10.4230/LIPIcs.IPEC.2020.31

PACE Solver Description: Computing Exact Treedepth via Minimal Separators

Authors: Zijian Xu, Dejun Mao, and Vorapong Suppakitpaisarn

Published in: LIPIcs, Volume 180, 15th International Symposium on Parameterized and Exact Computation (IPEC 2020)

Abstract

This is a description of team xuzijian629’s treedepth solver submitted to PACE 2020. As we use a top-down approach, we enumerate all possible minimal separators at each step. The enumeration is sped up by several novel pruning techniques and is based on our conjecture that we can always have an optimal decomposition without using separators with size larger than treewidth. Although we cannot theoretically guarantee that our algorithm based on the unproved conjecture can always give an optimal solution, it can give optimal solutions for all instances in our experiments. The algorithm solved 68 private instances and placed 5th in the competition.

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Zijian Xu, Dejun Mao, and Vorapong Suppakitpaisarn. PACE Solver Description: Computing Exact Treedepth via Minimal Separators. In 15th International Symposium on Parameterized and Exact Computation (IPEC 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 180, pp. 31:1-31:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{xu_et_al:LIPIcs.IPEC.2020.31,
  author =	{Xu, Zijian and Mao, Dejun and Suppakitpaisarn, Vorapong},
  title =	{{PACE Solver Description: Computing Exact Treedepth via Minimal Separators}},
  booktitle =	{15th International Symposium on Parameterized and Exact Computation (IPEC 2020)},
  pages =	{31:1--31:4},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-172-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{180},
  editor =	{Cao, Yixin and Pilipczuk, Marcin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.IPEC.2020.31},
  URN =		{urn:nbn:de:0030-drops-133340},
  doi =		{10.4230/LIPIcs.IPEC.2020.31},
  annote =	{Keywords: Treedepth, Minimal Separators, Experimental Algorithm}
}

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Documents authored by Suppakitpaisarn, Vorapong

Submodularity Property for Facility Locations of Dynamic Flow Networks

Abstract

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PACE Solver Description: Computing Exact Treedepth via Minimal Separators

Abstract

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