The Rate-Immediacy Barrier in Explicit Tree Code Constructions

Fuente: arXiv
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Main Authors: Cohen, Gil, Schulman, Leonard J., Srivastava, Piyush
Format: Preprint
Published: 2025
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_version_ 1866917521010982912
author Cohen, Gil
Schulman, Leonard J.
Srivastava, Piyush
author_facet Cohen, Gil
Schulman, Leonard J.
Srivastava, Piyush
contents Since the introduction of tree codes by Schulman (STOC 1993), explicit construction of asymptotically good tree codes has remained a notorious challenge. A work by Cohen, Haeupler and Schulman (STOC 2018), as well as the state-of-the-art construction by Ben Yaacov, Cohen, and Yankovitz (STOC 2022) have achieved codes with rate $Ω(1/\log\log n)$, exponentially improving upon the original rate $Ω(1/\log n)$ construction of Evans, Klugerman and Schulman from 1994. All of these constructions rely, at least in part, on increasingly sophisticated methods of combining (block) error-correcting codes. In this work, we identify a fundamental barrier to constructing tree codes using known techniques. We introduce a key property which we call immediacy, that, while not required by the original definition of tree codes, is shared by all known constructions and inherently arises in recursive combinations of error-correcting codes. Our main technical contribution is the proof of a rate-immediacy trade-off, which, in particular, implies that any tree code with constant distance and non-trivial immediacy must necessarily have vanishing rate. By applying our rate-immediacy trade-off to existing constructions, we establish that their known rate analyses are essentially optimal given their actual error-correction properties. More broadly, our work highlights the need for fundamentally new ideas -- beyond the recursive use of error-correcting codes -- to achieve substantial progress in explicitly constructing asymptotically good tree codes.
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id arxiv_https___arxiv_org_abs_2504_09388
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Rate-Immediacy Barrier in Explicit Tree Code Constructions
Cohen, Gil
Schulman, Leonard J.
Srivastava, Piyush
Information Theory
Computational Complexity
Discrete Mathematics
Since the introduction of tree codes by Schulman (STOC 1993), explicit construction of asymptotically good tree codes has remained a notorious challenge. A work by Cohen, Haeupler and Schulman (STOC 2018), as well as the state-of-the-art construction by Ben Yaacov, Cohen, and Yankovitz (STOC 2022) have achieved codes with rate $Ω(1/\log\log n)$, exponentially improving upon the original rate $Ω(1/\log n)$ construction of Evans, Klugerman and Schulman from 1994. All of these constructions rely, at least in part, on increasingly sophisticated methods of combining (block) error-correcting codes. In this work, we identify a fundamental barrier to constructing tree codes using known techniques. We introduce a key property which we call immediacy, that, while not required by the original definition of tree codes, is shared by all known constructions and inherently arises in recursive combinations of error-correcting codes. Our main technical contribution is the proof of a rate-immediacy trade-off, which, in particular, implies that any tree code with constant distance and non-trivial immediacy must necessarily have vanishing rate. By applying our rate-immediacy trade-off to existing constructions, we establish that their known rate analyses are essentially optimal given their actual error-correction properties. More broadly, our work highlights the need for fundamentally new ideas -- beyond the recursive use of error-correcting codes -- to achieve substantial progress in explicitly constructing asymptotically good tree codes.
title The Rate-Immediacy Barrier in Explicit Tree Code Constructions
topic Information Theory
Computational Complexity
Discrete Mathematics
url https://arxiv.org/abs/2504.09388