Random Variables, Conditional Independence and Categories of Abstract Sample Spaces

Fuente: arXiv
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Autore principale: Stein, Dario
Natura: Preprint
Pubblicazione: 2025
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author Stein, Dario
author_facet Stein, Dario
contents Two high-level "pictures" of probability theory have emerged: one that takes as central the notion of random variable, and one that focuses on distributions and probability channels (Markov kernels). While the channel-based picture has been successfully axiomatized, and widely generalized, using the notion of Markov category, the categorical semantics of the random variable picture remain less clear. Simpson's probability sheaves are a recent approach, in which probabilistic concepts like random variables are allowed vary over a site of sample spaces. Simpson has identified rich structure on these sites, most notably an abstract notion of conditional independence, and given examples ranging from probability over databases to nominal sets. We aim bring this development together with the generality and abstraction of Markov categories: We show that for any suitable Markov category, a category of sample spaces can be defined which satisfies Simpson's axioms, and that a theory of probability sheaves can be developed purely synthetically in this setting. We recover Simpson's examples in a uniform fashion from well-known Markov categories, and consider further generalizations.
format Preprint
id arxiv_https___arxiv_org_abs_2503_02477
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Random Variables, Conditional Independence and Categories of Abstract Sample Spaces
Stein, Dario
Category Theory
Logic in Computer Science
Programming Languages
Probability
F.4.1; G.3
Two high-level "pictures" of probability theory have emerged: one that takes as central the notion of random variable, and one that focuses on distributions and probability channels (Markov kernels). While the channel-based picture has been successfully axiomatized, and widely generalized, using the notion of Markov category, the categorical semantics of the random variable picture remain less clear. Simpson's probability sheaves are a recent approach, in which probabilistic concepts like random variables are allowed vary over a site of sample spaces. Simpson has identified rich structure on these sites, most notably an abstract notion of conditional independence, and given examples ranging from probability over databases to nominal sets. We aim bring this development together with the generality and abstraction of Markov categories: We show that for any suitable Markov category, a category of sample spaces can be defined which satisfies Simpson's axioms, and that a theory of probability sheaves can be developed purely synthetically in this setting. We recover Simpson's examples in a uniform fashion from well-known Markov categories, and consider further generalizations.
title Random Variables, Conditional Independence and Categories of Abstract Sample Spaces
topic Category Theory
Logic in Computer Science
Programming Languages
Probability
F.4.1; G.3
url https://arxiv.org/abs/2503.02477