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Entropy 2015, 17(5), 3253-3318;

The Homological Nature of Entropy

Max Planck Institute for Mathematics in the Sciences, Inselstrasse 22, 04103 Leipzig, Germany
Universite Paris Diderot-Paris 7, UFR de Mathematiques, Equipe Geometrie et Dynamique, Batiment Sophie Germain, 5 rue Thomas Mann, 75205 Paris Cedex 13, France
This paper is an extended version of our paper published in Proceedings of the MaxEnt 2014 Conference on Bayesian Inference and Maximum Entropy Methods in Science and Engineering, Amboise, France, 21–26 September 2014.
Author to whom correspondence should be addressed.
Received: 31 January 2015 / Revised: 3 May 2015 / Accepted: 5 May 2015 / Published: 13 May 2015
(This article belongs to the Special Issue Information, Entropy and Their Geometric Structures)
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We propose that entropy is a universal co-homological class in a theory associated to a family of observable quantities and a family of probability distributions. Three cases are presented: (1) classical probabilities and random variables; (2) quantum probabilities and observable operators; (3) dynamic probabilities and observation trees. This gives rise to a new kind of topology for information processes, that accounts for the main information functions: entropy, mutual-informations at all orders, and Kullback–Leibler divergence and generalizes them in several ways. The article is divided into two parts, that can be read independently. In the first part, the introduction, we provide an overview of the results, some open questions, future results and lines of research, and discuss briefly the application to complex data. In the second part we give the complete definitions and proofs of the theorems A, C and E in the introduction, which show why entropy is the first homological invariant of a structure of information in four contexts: static classical or quantum probability, dynamics of classical or quantum strategies of observation of a finite system. View Full-Text
Keywords: Shannon information; homology theory; entropy; quantum information; homotopy of links; mutual informations; Kullback–Leiber divergence; trees; monads; partitions Shannon information; homology theory; entropy; quantum information; homotopy of links; mutual informations; Kullback–Leiber divergence; trees; monads; partitions
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Baudot, P.; Bennequin, D. The Homological Nature of Entropy. Entropy 2015, 17, 3253-3318.

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