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Main Author: Luo, Wei
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.30389
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_version_ 1866917544966750208
author Luo, Wei
author_facet Luo, Wei
contents Pattern languages are a classical model in formal language theory and algorithmic learning theory. This note formulates the problem of computing the inclusion depth of a pattern language: the length of the longest strict inclusion chain from the universal pattern language to the language generated by a given pattern. Inclusion depth captures the mind-change complexity of pattern identification from positive data. The central open question is whether the inclusion depth ID_Sigma(p) is computable for every pattern p over every finite alphabet Sigma with at least two symbols, and whether it is computable in polynomial time. A simple conjectured formula, ID_Sigma(p) = 2|p| - #var(p) - 1, would imply a linear-time algorithm. The problem connects pattern language inclusion, combinatorics on words, language identification in the limit, and mind-change-bounded learning.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30389
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Inclusion Depth of Pattern Languages: An Open Problem in Algorithmic Learning Theory
Luo, Wei
Formal Languages and Automata Theory
Machine Learning
F.4.3; F.1.1; I.2.6
Pattern languages are a classical model in formal language theory and algorithmic learning theory. This note formulates the problem of computing the inclusion depth of a pattern language: the length of the longest strict inclusion chain from the universal pattern language to the language generated by a given pattern. Inclusion depth captures the mind-change complexity of pattern identification from positive data. The central open question is whether the inclusion depth ID_Sigma(p) is computable for every pattern p over every finite alphabet Sigma with at least two symbols, and whether it is computable in polynomial time. A simple conjectured formula, ID_Sigma(p) = 2|p| - #var(p) - 1, would imply a linear-time algorithm. The problem connects pattern language inclusion, combinatorics on words, language identification in the limit, and mind-change-bounded learning.
title The Inclusion Depth of Pattern Languages: An Open Problem in Algorithmic Learning Theory
topic Formal Languages and Automata Theory
Machine Learning
F.4.3; F.1.1; I.2.6
url https://arxiv.org/abs/2605.30389