Geometry of q-Exponential Family of Probability Distributions

The Gibbs distribution of statistical physics is an exponential family of probability distributions, which has a mathematical basis of duality in the form of the Legendre transformation. Recent studies of complex systems have found lots of distributions obeying the power law rather than the standard...

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Main Authors: Shun-ichi Amari, Atsumi Ohara
Format: Article
Language:English
Published: MDPI AG 2011-06-01
Series:Entropy
Subjects:
Online Access:http://www.mdpi.com/1099-4300/13/6/1170/
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author Shun-ichi Amari
Atsumi Ohara
author_facet Shun-ichi Amari
Atsumi Ohara
author_sort Shun-ichi Amari
collection DOAJ
description The Gibbs distribution of statistical physics is an exponential family of probability distributions, which has a mathematical basis of duality in the form of the Legendre transformation. Recent studies of complex systems have found lots of distributions obeying the power law rather than the standard Gibbs type distributions. The Tsallis q-entropy is a typical example capturing such phenomena. We treat the q-Gibbs distribution or the q-exponential family by generalizing the exponential function to the q-family of power functions, which is useful for studying various complex or non-standard physical phenomena. We give a new mathematical structure to the q-exponential family different from those previously given. It has a dually flat geometrical structure derived from the Legendre transformation and the conformal geometry is useful for understanding it. The q-version of the maximum entropy theorem is naturally induced from the q-Pythagorean theorem. We also show that the maximizer of the q-escort distribution is a Bayesian MAP (Maximum A posteriori Probability) estimator.
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spelling doaj.art-7a608bf6862f4323b6f5bc1b2e9e9d412022-12-22T03:58:36ZengMDPI AGEntropy1099-43002011-06-011361170118510.3390/e13061170Geometry of q-Exponential Family of Probability DistributionsShun-ichi AmariAtsumi OharaThe Gibbs distribution of statistical physics is an exponential family of probability distributions, which has a mathematical basis of duality in the form of the Legendre transformation. Recent studies of complex systems have found lots of distributions obeying the power law rather than the standard Gibbs type distributions. The Tsallis q-entropy is a typical example capturing such phenomena. We treat the q-Gibbs distribution or the q-exponential family by generalizing the exponential function to the q-family of power functions, which is useful for studying various complex or non-standard physical phenomena. We give a new mathematical structure to the q-exponential family different from those previously given. It has a dually flat geometrical structure derived from the Legendre transformation and the conformal geometry is useful for understanding it. The q-version of the maximum entropy theorem is naturally induced from the q-Pythagorean theorem. We also show that the maximizer of the q-escort distribution is a Bayesian MAP (Maximum A posteriori Probability) estimator.http://www.mdpi.com/1099-4300/13/6/1170/q-exponential familyq-entropyinformation geometryq-Pythagorean theoremq-Max-Ent theoremconformal transformation
spellingShingle Shun-ichi Amari
Atsumi Ohara
Geometry of q-Exponential Family of Probability Distributions
Entropy
q-exponential family
q-entropy
information geometry
q-Pythagorean theorem
q-Max-Ent theorem
conformal transformation
title Geometry of q-Exponential Family of Probability Distributions
title_full Geometry of q-Exponential Family of Probability Distributions
title_fullStr Geometry of q-Exponential Family of Probability Distributions
title_full_unstemmed Geometry of q-Exponential Family of Probability Distributions
title_short Geometry of q-Exponential Family of Probability Distributions
title_sort geometry of q exponential family of probability distributions
topic q-exponential family
q-entropy
information geometry
q-Pythagorean theorem
q-Max-Ent theorem
conformal transformation
url http://www.mdpi.com/1099-4300/13/6/1170/
work_keys_str_mv AT shunichiamari geometryofqexponentialfamilyofprobabilitydistributions
AT atsumiohara geometryofqexponentialfamilyofprobabilitydistributions