Undirected Multicast Network Coding Gaps via Locally Decodable Codes

Fuente: arXiv
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Autores principales: Braverman, Mark, He, Zhongtian
Formato: Preprint
Publicado: 2025
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author Braverman, Mark
He, Zhongtian
author_facet Braverman, Mark
He, Zhongtian
contents The network coding problem asks whether data throughput in a network can be increased using coding (compared to treating bits as commodities in a flow). While it is well-known that a network coding advantage exists in directed graphs, the situation in undirected graphs is much less understood -- in particular, despite significant effort, it is not even known whether network coding is helpful at all for unicast sessions. In this paper we study the multi-source multicast network coding problem in undirected graphs. There are $k$ sources broadcasting each to a subset of nodes in a graph of size $n$. The corresponding combinatorial problem is a version of the Steiner tree packing problem, and the network coding question asks whether the multicast coding rate exceeds the tree-packing rate. We give the first super-constant bound to this problem, demonstrating an example with a coding advantage of $Ω(\log k)$. In terms of graph size, we obtain a lower bound of $2^{\tildeΩ(\sqrt{\log \log n})}$. We also obtain an upper bound of $O(\log n)$ on the gap. Our main technical contribution is a new reduction that converts locally-decodable codes in the low-error regime into multicast coding instances. This gives rise to a new family of explicitly constructed graphs, which may have other applications.
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id arxiv_https___arxiv_org_abs_2510_18737
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Undirected Multicast Network Coding Gaps via Locally Decodable Codes
Braverman, Mark
He, Zhongtian
Computational Complexity
Discrete Mathematics
Data Structures and Algorithms
Information Theory
The network coding problem asks whether data throughput in a network can be increased using coding (compared to treating bits as commodities in a flow). While it is well-known that a network coding advantage exists in directed graphs, the situation in undirected graphs is much less understood -- in particular, despite significant effort, it is not even known whether network coding is helpful at all for unicast sessions. In this paper we study the multi-source multicast network coding problem in undirected graphs. There are $k$ sources broadcasting each to a subset of nodes in a graph of size $n$. The corresponding combinatorial problem is a version of the Steiner tree packing problem, and the network coding question asks whether the multicast coding rate exceeds the tree-packing rate. We give the first super-constant bound to this problem, demonstrating an example with a coding advantage of $Ω(\log k)$. In terms of graph size, we obtain a lower bound of $2^{\tildeΩ(\sqrt{\log \log n})}$. We also obtain an upper bound of $O(\log n)$ on the gap. Our main technical contribution is a new reduction that converts locally-decodable codes in the low-error regime into multicast coding instances. This gives rise to a new family of explicitly constructed graphs, which may have other applications.
title Undirected Multicast Network Coding Gaps via Locally Decodable Codes
topic Computational Complexity
Discrete Mathematics
Data Structures and Algorithms
Information Theory
url https://arxiv.org/abs/2510.18737