On the Statistical Query Complexity of Learning Semiautomata: a Random Walk Approach

Fuente: arXiv
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Autores principales: Giapitzakis, George, Fountoulakis, Kimon, Nichani, Eshaan, Lee, Jason D.
Formato: Preprint
Publicado: 2025
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author Giapitzakis, George
Fountoulakis, Kimon
Nichani, Eshaan
Lee, Jason D.
author_facet Giapitzakis, George
Fountoulakis, Kimon
Nichani, Eshaan
Lee, Jason D.
contents Semiautomata form a rich class of sequence-processing algorithms with applications in natural language processing, robotics, computational biology, and data mining. We establish the first Statistical Query hardness result for semiautomata under the uniform distribution over input words and initial states. We show that Statistical Query hardness can be established when both the alphabet size and input length are polynomial in the number of states. Unlike the case of deterministic finite automata, where hardness typically arises through the hardness of the language they recognize (e.g., parity), our result is derived solely from the internal state-transition structure of semiautomata. Our analysis reduces the task of distinguishing the final states of two semiautomata to studying the behavior of a random walk on the group $S_{N} \times S_{N}$. By applying tools from Fourier analysis and the representation theory of the symmetric group, we obtain tight spectral gap bounds, demonstrating that after a polynomial number of steps in the number of states, distinct semiautomata become nearly uncorrelated, yielding the desired hardness result.
format Preprint
id arxiv_https___arxiv_org_abs_2510_04115
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Statistical Query Complexity of Learning Semiautomata: a Random Walk Approach
Giapitzakis, George
Fountoulakis, Kimon
Nichani, Eshaan
Lee, Jason D.
Machine Learning
Semiautomata form a rich class of sequence-processing algorithms with applications in natural language processing, robotics, computational biology, and data mining. We establish the first Statistical Query hardness result for semiautomata under the uniform distribution over input words and initial states. We show that Statistical Query hardness can be established when both the alphabet size and input length are polynomial in the number of states. Unlike the case of deterministic finite automata, where hardness typically arises through the hardness of the language they recognize (e.g., parity), our result is derived solely from the internal state-transition structure of semiautomata. Our analysis reduces the task of distinguishing the final states of two semiautomata to studying the behavior of a random walk on the group $S_{N} \times S_{N}$. By applying tools from Fourier analysis and the representation theory of the symmetric group, we obtain tight spectral gap bounds, demonstrating that after a polynomial number of steps in the number of states, distinct semiautomata become nearly uncorrelated, yielding the desired hardness result.
title On the Statistical Query Complexity of Learning Semiautomata: a Random Walk Approach
topic Machine Learning
url https://arxiv.org/abs/2510.04115