First order complexity of finite random structures

Fuente: arXiv
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Autori principali: Demin, Danila, Zhukovskii, Maksim
Natura: Preprint
Pubblicazione: 2024
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author Demin, Danila
Zhukovskii, Maksim
author_facet Demin, Danila
Zhukovskii, Maksim
contents For a sequence of random structures with $n$-element domains over a relational signature, we define its first order (FO) complexity as a certain subset in the Banach space $\ell^{\infty}/c_0$. The well-known FO zero-one law and FO convergence law correspond to FO complexities equal to $\{0,1\}$ and a subset of $\mathbb{R}$, respectively. We present a hierarchy of FO complexity classes, introduce a stochastic FO reduction that allows to transfer complexity results between different random structures, and deduce using this tool several new logical limit laws for binomial random structures. Finally, we introduce a conditional distribution on graphs, subject to a FO sentence $φ$, that generalises certain well-known random graph models, show instances of this distribution for every complexity class, and prove that the set of all $φ$ validating 0--1 law is not recursively enumerable.
format Preprint
id arxiv_https___arxiv_org_abs_2402_02567
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle First order complexity of finite random structures
Demin, Danila
Zhukovskii, Maksim
Logic in Computer Science
Discrete Mathematics
Combinatorics
Logic
Probability
For a sequence of random structures with $n$-element domains over a relational signature, we define its first order (FO) complexity as a certain subset in the Banach space $\ell^{\infty}/c_0$. The well-known FO zero-one law and FO convergence law correspond to FO complexities equal to $\{0,1\}$ and a subset of $\mathbb{R}$, respectively. We present a hierarchy of FO complexity classes, introduce a stochastic FO reduction that allows to transfer complexity results between different random structures, and deduce using this tool several new logical limit laws for binomial random structures. Finally, we introduce a conditional distribution on graphs, subject to a FO sentence $φ$, that generalises certain well-known random graph models, show instances of this distribution for every complexity class, and prove that the set of all $φ$ validating 0--1 law is not recursively enumerable.
title First order complexity of finite random structures
topic Logic in Computer Science
Discrete Mathematics
Combinatorics
Logic
Probability
url https://arxiv.org/abs/2402.02567