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What and Who

Maximum Flow by Augmenting Paths in n^(2+o(1)) Time

Joakim Oscar Blikstad
KTH Royal Institute of Technology, Sweden
AG1 Mittagsseminar (own work)
AG 1  
AG Audience
English

Date, Time and Location

Tuesday, 10 September 2024
13:00
60 Minutes
E1 4
024
Saarbrücken

Abstract

This talk presents a combinatorial algorithm for computing exact maximum flows in directed graphs with n vertices and edge capacities from {1,…,U} in n^(2+o(1)) log U time, which is almost optimal in dense graphs. The algorithm is a novel implementation of the classical augmenting-path framework; we list augmenting paths more efficiently using a new variant of the push-relabel algorithm that uses additional edge weights to guide the algorithm, and we derive the edge weights by constructing a directed expander hierarchy.


Even in unit-capacity graphs, this breaks the long-standing O(m⋅min{sqtrt(m),n^(2/3)}) time bound of the previous combinatorial algorithms by Karzanov (1973) and Even and Tarjan (1975) when the graph has m=ω(n^(4/3)) edges. Notably, our approach does not rely on continuous optimization nor heavy dynamic graph data structures, both of which are crucial in the recent developments that led to the almost-linear time algorithm by Chen et al. (FOCS 2022). Our running time also matches the n^(2+o(1)) time bound of the independent combinatorial algorithm by Chuzhoy and Khanna (STOC 2024) for computing the maximum bipartite matching, a special case of maximum flow.

Talk based on paper: "Maximum Flow by Augmenting Paths in n^(2+o(1)) Time", to appear in FOCS 2024, https://arxiv.org/abs/2406.03648.
Joint work with Aaron Bernstein, Thatchaphol Saranurak, Ta-Wei Tu.

Contact

Nidhi Rathi
+49 681 9325 1134
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Virtual Meeting Details

Zoom
649 2184 1396
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Nidhi Rathi, 09/09/2024 11:45
Nidhi Rathi, 08/06/2024 12:12
Nidhi Rathi, 08/06/2024 10:28 -- Created document.