Classifying Causal Structures: Ascertaining when Classical Correlations are Constrained by Inequalities

Fuente: arXiv
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Main Authors: Khanna, Shashaank, Ansanelli, Marina Maciel, Pusey, Matthew F., Wolfe, Elie
Format: Preprint
Published: 2023
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author Khanna, Shashaank
Ansanelli, Marina Maciel
Pusey, Matthew F.
Wolfe, Elie
author_facet Khanna, Shashaank
Ansanelli, Marina Maciel
Pusey, Matthew F.
Wolfe, Elie
contents The classical causal relations between a set of variables, some observed and some latent, can induce both equality constraints (typically conditional independences) as well as inequality constraints (Instrumental and Bell inequalities being prototypical examples) on their compatible distribution over the observed variables. Enumerating a causal structure's implied inequality constraints is generally far more difficult than enumerating its equalities. Furthermore, only inequality constraints ever admit violation by quantum correlations. For both those reasons, it is important to classify causal scenarios into those which impose inequality constraints versus those which do not. Here we develop methods for detecting such scenarios by appealing to d-separation, e-separation, and incompatible supports. Many (perhaps all?) scenarios with exclusively equality constraints can be detected via a condition articulated by Henson, Lal and Pusey (HLP). Considering all scenarios with up to 4 observed variables, which number in the thousands, we are able to resolve all but three causal scenarios, providing evidence that the HLP condition is, in fact, exhaustive.
format Preprint
id arxiv_https___arxiv_org_abs_2308_02380
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Classifying Causal Structures: Ascertaining when Classical Correlations are Constrained by Inequalities
Khanna, Shashaank
Ansanelli, Marina Maciel
Pusey, Matthew F.
Wolfe, Elie
Quantum Physics
Statistics Theory
Machine Learning
The classical causal relations between a set of variables, some observed and some latent, can induce both equality constraints (typically conditional independences) as well as inequality constraints (Instrumental and Bell inequalities being prototypical examples) on their compatible distribution over the observed variables. Enumerating a causal structure's implied inequality constraints is generally far more difficult than enumerating its equalities. Furthermore, only inequality constraints ever admit violation by quantum correlations. For both those reasons, it is important to classify causal scenarios into those which impose inequality constraints versus those which do not. Here we develop methods for detecting such scenarios by appealing to d-separation, e-separation, and incompatible supports. Many (perhaps all?) scenarios with exclusively equality constraints can be detected via a condition articulated by Henson, Lal and Pusey (HLP). Considering all scenarios with up to 4 observed variables, which number in the thousands, we are able to resolve all but three causal scenarios, providing evidence that the HLP condition is, in fact, exhaustive.
title Classifying Causal Structures: Ascertaining when Classical Correlations are Constrained by Inequalities
topic Quantum Physics
Statistics Theory
Machine Learning
url https://arxiv.org/abs/2308.02380