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Documents authored by Dippel, Jack

Document
DOI: 10.4230/LIPIcs.STACS.2024.28
One n Remains to Settle the Tree Conjecture

Authors: Jack Dippel and Adrian Vetta

Published in: LIPIcs, Volume 289, 41st International Symposium on Theoretical Aspects of Computer Science (STACS 2024)

Abstract
In the famous network creation game of Fabrikant et al. [Fabrikant et al., 2003] a set of agents play a game to build a connected graph. The n agents form the vertex set V of the graph and each vertex v ∈ V buys a set E_v of edges inducing a graph G = (V,⋃_{v∈V} E_v). The private objective of each vertex is to minimize the sum of its building cost (the cost of the edges it buys) plus its connection cost (the total distance from itself to every other vertex). Given a cost of α for each individual edge, a long-standing conjecture, called the tree conjecture, states that if α > n then every Nash equilibrium graph in the game is a spanning tree. After a plethora of work, it is known that the conjecture holds for any α > 3n-3. In this paper we prove the tree conjecture holds for α > 2n. This reduces by half the open range for α with only (n-3, 2n) remaining in order to settle the conjecture.
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Jack Dippel and Adrian Vetta. One n Remains to Settle the Tree Conjecture. In 41st International Symposium on Theoretical Aspects of Computer Science (STACS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 289, pp. 28:1-28:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{dippel_et_al:LIPIcs.STACS.2024.28,
  author =	{Dippel, Jack and Vetta, Adrian},
  title =	{{One n Remains to Settle the Tree Conjecture}},
  booktitle =	{41st International Symposium on Theoretical Aspects of Computer Science (STACS 2024)},
  pages =	{28:1--28:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-311-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{289},
  editor =	{Beyersdorff, Olaf and Kant\'{e}, Mamadou Moustapha and Kupferman, Orna and Lokshtanov, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2024.28},
  URN =		{urn:nbn:de:0030-drops-197388},
  doi =		{10.4230/LIPIcs.STACS.2024.28},
  annote =	{Keywords: Algorithmic Game Theory, Network Creation Games, Tree Conjecture}
}
Document
DOI: 10.4230/LIPIcs.ISAAC.2021.38
An Improved Approximation Algorithm for the Matching Augmentation Problem

Authors: Joseph Cheriyan, Robert Cummings, Jack Dippel, and Jasper Zhu

Published in: LIPIcs, Volume 212, 32nd International Symposium on Algorithms and Computation (ISAAC 2021)

Abstract
We present a 5/3-approximation algorithm for the matching augmentation problem (MAP): given a multi-graph with edges of cost either zero or one such that the edges of cost zero form a matching, find a 2-edge connected spanning subgraph (2-ECSS) of minimum cost. A 7/4-approximation algorithm for the same problem was presented recently, see Cheriyan, et al., "The matching augmentation problem: a 7/4-approximation algorithm," Math. Program., 182(1):315-354, 2020. Our improvement is based on new algorithmic techniques, and some of these may lead to advances on related problems.
Cite as

Joseph Cheriyan, Robert Cummings, Jack Dippel, and Jasper Zhu. An Improved Approximation Algorithm for the Matching Augmentation Problem. In 32nd International Symposium on Algorithms and Computation (ISAAC 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 212, pp. 38:1-38:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{cheriyan_et_al:LIPIcs.ISAAC.2021.38,
  author =	{Cheriyan, Joseph and Cummings, Robert and Dippel, Jack and Zhu, Jasper},
  title =	{{An Improved Approximation Algorithm for the Matching Augmentation Problem}},
  booktitle =	{32nd International Symposium on Algorithms and Computation (ISAAC 2021)},
  pages =	{38:1--38:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-214-3},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{212},
  editor =	{Ahn, Hee-Kap and Sadakane, Kunihiko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2021.38},
  URN =		{urn:nbn:de:0030-drops-154714},
  doi =		{10.4230/LIPIcs.ISAAC.2021.38},
  annote =	{Keywords: 2-Edge connected graph, 2-edge covers, approximation algorithms, connectivity augmentation, forest augmentation problem, matching augmentation problem, network design}
}
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