Deterministic Online Bipartite Edge Coloring

Fuente: arXiv
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Main Authors: Blikstad, Joakim, Svensson, Ola, Vintan, Radu, Wajc, David
Format: Preprint
Published: 2024
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author Blikstad, Joakim
Svensson, Ola
Vintan, Radu
Wajc, David
author_facet Blikstad, Joakim
Svensson, Ola
Vintan, Radu
Wajc, David
contents We study online bipartite edge coloring, with nodes on one side of the graph revealed sequentially. The trivial greedy algorithm is $(2-o(1))$-competitive, which is optimal for graphs of low maximum degree, $Δ=O(\log n)$ [BNMN IPL'92]. Numerous online edge-coloring algorithms outperforming the greedy algorithm in various settings were designed over the years (e.g., AGKM FOCS'03, BMM SODA'10, CPW FOCS'19, BGW SODA'21, KLSST STOC'22, BSVW STOC'24), all crucially relying on randomization. A commonly-held belief, first stated by [BNMN IPL'92], is that randomization is necessary to outperform greedy. Surprisingly, we refute this belief, by presenting a deterministic algorithm that beats greedy for sufficiently large $Δ=Ω(\log n)$, and in particular has competitive ratio $\frac{e}{e-1}+o(1)$ for all $Δ=ω(\log n)$. We obtain our result via a new and surprisingly simple randomized algorithm that works against adaptive adversaries (as opposed to oblivious adversaries assumed by prior work), which implies the existence of a similarly-competitive deterministic algorithm [BDBKTW STOC'90].
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id arxiv_https___arxiv_org_abs_2408_03661
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Deterministic Online Bipartite Edge Coloring
Blikstad, Joakim
Svensson, Ola
Vintan, Radu
Wajc, David
Data Structures and Algorithms
We study online bipartite edge coloring, with nodes on one side of the graph revealed sequentially. The trivial greedy algorithm is $(2-o(1))$-competitive, which is optimal for graphs of low maximum degree, $Δ=O(\log n)$ [BNMN IPL'92]. Numerous online edge-coloring algorithms outperforming the greedy algorithm in various settings were designed over the years (e.g., AGKM FOCS'03, BMM SODA'10, CPW FOCS'19, BGW SODA'21, KLSST STOC'22, BSVW STOC'24), all crucially relying on randomization. A commonly-held belief, first stated by [BNMN IPL'92], is that randomization is necessary to outperform greedy. Surprisingly, we refute this belief, by presenting a deterministic algorithm that beats greedy for sufficiently large $Δ=Ω(\log n)$, and in particular has competitive ratio $\frac{e}{e-1}+o(1)$ for all $Δ=ω(\log n)$. We obtain our result via a new and surprisingly simple randomized algorithm that works against adaptive adversaries (as opposed to oblivious adversaries assumed by prior work), which implies the existence of a similarly-competitive deterministic algorithm [BDBKTW STOC'90].
title Deterministic Online Bipartite Edge Coloring
topic Data Structures and Algorithms
url https://arxiv.org/abs/2408.03661