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Metrical Task Systems on Trees via Mirror Descent and Unfair Gluing

Published: 01 January 2021 Publication History

Abstract

We consider metrical task systems on tree metrics and present an $O(\mathrm{depth} \times \log n)$-competitive randomized algorithm based on the mirror descent framework introduced in our prior work on the $k$-server problem. For the special case of hierarchically separated trees (HSTs), we use mirror descent to refine the standard approach based on gluing unfair metrical task systems. This yields an $O(\log n)$-competitive algorithm for HSTs, thus removing an extraneous $\log\log n$ in the bound of Fiat and Mendel (2003). Combined with well-known HST embedding theorems, this also gives an $O((\log n)^2)$-competitive randomized algorithm for every $n$-point metric space.

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Published In

cover image SIAM Journal on Computing
SIAM Journal on Computing  Volume 50, Issue 3
DOI:10.1137/smjcat.50.3
Issue’s Table of Contents

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Society for Industrial and Applied Mathematics

United States

Publication History

Published: 01 January 2021

Author Tags

  1. online algorithms
  2. convex optimization
  3. finite metric space

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  1. 68W27

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View all
  • (2023)Smoothed online combinatorial optimization using imperfect predictionsProceedings of the Thirty-Seventh AAAI Conference on Artificial Intelligence and Thirty-Fifth Conference on Innovative Applications of Artificial Intelligence and Thirteenth Symposium on Educational Advances in Artificial Intelligence10.1609/aaai.v37i10.26430(12130-12137)Online publication date: 7-Feb-2023
  • (2023)The Online Pause and Resume Problem: Optimal Algorithms and An Application to Carbon-Aware Load ShiftingProceedings of the ACM on Measurement and Analysis of Computing Systems10.1145/36267767:3(1-32)Online publication date: 7-Dec-2023
  • (2023)Polylog-Competitive Algorithms for Dynamic Balanced Graph Partitioning for Ring DemandsProceedings of the 35th ACM Symposium on Parallelism in Algorithms and Architectures10.1145/3558481.3591097(403-413)Online publication date: 17-Jun-2023
  • (2022)Optimal Algorithms for Right-sizing Data CentersACM Transactions on Parallel Computing10.1145/35655139:4(1-40)Online publication date: 11-Oct-2022

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