Deterministic identification over channels with finite output: a dimensional perspective on superlinear rates
- URL: http://arxiv.org/abs/2402.09117v3
- Date: Tue, 04 Feb 2025 12:17:30 GMT
- Title: Deterministic identification over channels with finite output: a dimensional perspective on superlinear rates
- Authors: Pau Colomer, Christian Deppe, Holger Boche, Andreas Winter,
- Abstract summary: We consider the problem in its generality for memoryless channels with finite output, but arbitrary input alphabets.
Our main findings are that the maximum length of messages thus identifiable scales superlinearly as $R,nlog n$ with the block length $n$.
We show that it is sufficient to ensure pairwise reliable distinguishability of the output distributions to construct a DI code.
- Score: 49.126395046088014
- License:
- Abstract: Following initial work by JaJa, Ahlswede and Cai, and inspired by a recent renewed surge in interest in deterministic identification (DI) via noisy channels, we consider the problem in its generality for memoryless channels with finite output, but arbitrary input alphabets. Such a channel is essentially given by its output distributions as a subset in the probability simplex. Our main findings are that the maximum length of messages thus identifiable scales superlinearly as $R\,n\log n$ with the block length $n$, and that the optimal rate $R$ is bounded in terms of the covering (aka Minkowski, or Kolmogorov, or entropy) dimension $d$ of a certain algebraic transformation of the output set: $\frac14 d \leq R \leq \frac12 d$. Remarkably, both the lower and upper Minkowski dimensions play a role in this result. Along the way, we present a "Hypothesis Testing Lemma" showing that it is sufficient to ensure pairwise reliable distinguishability of the output distributions to construct a DI code. Although we do not know the exact capacity formula, we can conclude that the DI capacity exhibits superactivation: there exist channels whose capacities individually are zero, but whose product has positive capacity. We also generalise these results to classical-quantum channels with finite-dimensional output quantum system, in particular to quantum channels on finite-dimensional quantum systems under the constraint that the identification code can only use tensor product inputs.
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