Causal structures from entropic information: geometry and novel scenarios

Bell's theorem in physics, as well as causal discovery in machine learning, both face the problem of deciding whether observed data is compatible with a presumed causal relationship between the variables (for example, a local hidden variable model). Traditionally, Bell inequalities have been us...

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Main Authors: Rafael Chaves, Lukas Luft, David Gross
Format: Article
Language:English
Published: IOP Publishing 2014-01-01
Series:New Journal of Physics
Subjects:
Online Access:https://doi.org/10.1088/1367-2630/16/4/043001
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author Rafael Chaves
Lukas Luft
David Gross
author_facet Rafael Chaves
Lukas Luft
David Gross
author_sort Rafael Chaves
collection DOAJ
description Bell's theorem in physics, as well as causal discovery in machine learning, both face the problem of deciding whether observed data is compatible with a presumed causal relationship between the variables (for example, a local hidden variable model). Traditionally, Bell inequalities have been used to describe the restrictions imposed by causal structures on marginal distributions. However, some structures give rise to non-convex constraints on the accessible data, and it has recently been noted that linear inequalities on the observable entropies capture these situations more naturally. In this paper, we show the versatility of the entropic approach by greatly expanding the set of scenarios for which entropic constraints are known. For the first time, we treat Bell scenarios involving multiple parties and multiple observables per party. Going beyond the usual Bell setup, we exhibit inequalities for scenarios with extra conditional independence assumptions, as well as a limited amount of shared randomness between the parties. Many of our results are based on a geometric observation: Bell polytopes for two-outcome measurements can be naturally imbedded into the convex cone of attainable marginal entropies. Thus, any entropic inequality can be translated into one valid for probabilities. In some situations the converse also holds, which provides us with a rich source of candidate entropic inequalities.
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spelling doaj.art-07e4fa5ebe05440fa6d6aa4806e439702023-08-08T11:25:32ZengIOP PublishingNew Journal of Physics1367-26302014-01-0116404300110.1088/1367-2630/16/4/043001Causal structures from entropic information: geometry and novel scenariosRafael Chaves0Lukas Luft1David Gross2Institute for Physics, University of Freiburg , Rheinstrasse 10, D-79104 Freiburg, GermanyInstitute for Physics, University of Freiburg , Rheinstrasse 10, D-79104 Freiburg, GermanyInstitute for Physics, University of Freiburg , Rheinstrasse 10, D-79104 Freiburg, GermanyBell's theorem in physics, as well as causal discovery in machine learning, both face the problem of deciding whether observed data is compatible with a presumed causal relationship between the variables (for example, a local hidden variable model). Traditionally, Bell inequalities have been used to describe the restrictions imposed by causal structures on marginal distributions. However, some structures give rise to non-convex constraints on the accessible data, and it has recently been noted that linear inequalities on the observable entropies capture these situations more naturally. In this paper, we show the versatility of the entropic approach by greatly expanding the set of scenarios for which entropic constraints are known. For the first time, we treat Bell scenarios involving multiple parties and multiple observables per party. Going beyond the usual Bell setup, we exhibit inequalities for scenarios with extra conditional independence assumptions, as well as a limited amount of shared randomness between the parties. Many of our results are based on a geometric observation: Bell polytopes for two-outcome measurements can be naturally imbedded into the convex cone of attainable marginal entropies. Thus, any entropic inequality can be translated into one valid for probabilities. In some situations the converse also holds, which provides us with a rich source of candidate entropic inequalities.https://doi.org/10.1088/1367-2630/16/4/043001non-localitymarginal scenarioscausal structuresentropic inequalities
spellingShingle Rafael Chaves
Lukas Luft
David Gross
Causal structures from entropic information: geometry and novel scenarios
New Journal of Physics
non-locality
marginal scenarios
causal structures
entropic inequalities
title Causal structures from entropic information: geometry and novel scenarios
title_full Causal structures from entropic information: geometry and novel scenarios
title_fullStr Causal structures from entropic information: geometry and novel scenarios
title_full_unstemmed Causal structures from entropic information: geometry and novel scenarios
title_short Causal structures from entropic information: geometry and novel scenarios
title_sort causal structures from entropic information geometry and novel scenarios
topic non-locality
marginal scenarios
causal structures
entropic inequalities
url https://doi.org/10.1088/1367-2630/16/4/043001
work_keys_str_mv AT rafaelchaves causalstructuresfromentropicinformationgeometryandnovelscenarios
AT lukasluft causalstructuresfromentropicinformationgeometryandnovelscenarios
AT davidgross causalstructuresfromentropicinformationgeometryandnovelscenarios