Memory Uncertainty Relation and Harmonic Memory in Random Recurrent Networks

Fuente: arXiv
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Auteurs principaux: Haruna, Taichi, Nakajima, Kohei
Format: Preprint
Publié: 2026
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author Haruna, Taichi
Nakajima, Kohei
author_facet Haruna, Taichi
Nakajima, Kohei
contents We present an inequality that bounds the short-term memory capability of dynamical systems from below. It can be interpreted as an uncertainty relation between a measure of short-term memory and that of the size of state fluctuations induced by input signals. The lower bound can be achieved by a readout weight and thus represents a suboptimal memory called harmonic memory. We examine analytically and numerically the inequality in a number of reservoir systems subject to input noise. We illustrate cases in which equality is achieved exactly, equality holds asymptotically, and the inequality is strict. We also study the effect of a state-space regularization to elucidate the inequality in terms of the fluctuation structure of the state-space. We find that a certain strength of input noise induces extra memory under the regularization, and we refer to this phenomenon as noise-induced memory. We observe that the memory uncertainty relation does not hold in general for the regularized memory and harmonic memory. This fact is explained in terms of the mechanism of noise-induced memory.
format Preprint
id arxiv_https___arxiv_org_abs_2605_24628
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Memory Uncertainty Relation and Harmonic Memory in Random Recurrent Networks
Haruna, Taichi
Nakajima, Kohei
Adaptation and Self-Organizing Systems
Disordered Systems and Neural Networks
Neural and Evolutionary Computing
We present an inequality that bounds the short-term memory capability of dynamical systems from below. It can be interpreted as an uncertainty relation between a measure of short-term memory and that of the size of state fluctuations induced by input signals. The lower bound can be achieved by a readout weight and thus represents a suboptimal memory called harmonic memory. We examine analytically and numerically the inequality in a number of reservoir systems subject to input noise. We illustrate cases in which equality is achieved exactly, equality holds asymptotically, and the inequality is strict. We also study the effect of a state-space regularization to elucidate the inequality in terms of the fluctuation structure of the state-space. We find that a certain strength of input noise induces extra memory under the regularization, and we refer to this phenomenon as noise-induced memory. We observe that the memory uncertainty relation does not hold in general for the regularized memory and harmonic memory. This fact is explained in terms of the mechanism of noise-induced memory.
title Memory Uncertainty Relation and Harmonic Memory in Random Recurrent Networks
topic Adaptation and Self-Organizing Systems
Disordered Systems and Neural Networks
Neural and Evolutionary Computing
url https://arxiv.org/abs/2605.24628