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On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus

Jan A. Bergstra Orcid Logo, John Tucker Orcid Logo

Entropy, Volume: 27, Issue: 1, Start page: 31

Swansea University Author: John Tucker Orcid Logo

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DOI (Published version): 10.3390/e27010031

Abstract

Classic formulae for entropy and cross-entropy contain operations 0 and log2 that are not defined on all inputs. This can lead to calculations with problematic subexpressions such as 0 log2 0 and uncertainties in large scale calculations; partiality also introduces complications in logical analysis....

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Published in: Entropy
ISSN: 1099-4300
Published: MDPI AG 2025
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URI: https://cronfa.swan.ac.uk/Record/cronfa68639
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last_indexed 2025-02-08T05:44:34Z
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spelling 2025-02-07T14:48:04.1928910 v2 68639 2025-01-02 On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus 431b3060563ed44cc68c7056ece2f85e 0000-0003-4689-8760 John Tucker John Tucker true false 2025-01-02 MACS Classic formulae for entropy and cross-entropy contain operations 0 and log2 that are not defined on all inputs. This can lead to calculations with problematic subexpressions such as 0 log2 0 and uncertainties in large scale calculations; partiality also introduces complications in logical analysis. Instead of adding conventions or splitting formulae into cases, we create a new algebra of real numbers with two symbols ±∞ for signed infinite values and a symbol named ⊥ for the undefined. In this resulting arithmetic, entropy, cross-entropy, Kullback–Leibler divergence, and Shannon divergence can be expressed without concerning any further conventions. The algebra may form a basis for probability theory more generally. Journal Article Entropy 27 1 31 MDPI AG 1099-4300 Partial formulae; fracterm calculus; transreals; entropic transreals; peripheral numbers; entropy; cross-entropy 2 1 2025 2025-01-02 10.3390/e27010031 COLLEGE NANME Mathematics and Computer Science School COLLEGE CODE MACS Swansea University Another institution paid the OA fee This research received no external funding. 2025-02-07T14:48:04.1928910 2025-01-02T15:25:16.0368950 Faculty of Science and Engineering School of Mathematics and Computer Science - Computer Science Jan A. Bergstra 0000-0003-2492-506x 1 John Tucker 0000-0003-4689-8760 2 68639__33302__aacc8d1138f74147b5f410243e66ae58.pdf 68639.VOR.pdf 2025-01-13T14:04:48.2562177 Output 264571 application/pdf Version of Record true © 2025 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. true eng https://creativecommons.org/licenses/by/4.0/
title On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
spellingShingle On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
John Tucker
title_short On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
title_full On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
title_fullStr On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
title_full_unstemmed On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
title_sort On Defining Expressions for Entropy and Cross-Entropy: The Entropic Transreals and Their Fracterm Calculus
author_id_str_mv 431b3060563ed44cc68c7056ece2f85e
author_id_fullname_str_mv 431b3060563ed44cc68c7056ece2f85e_***_John Tucker
author John Tucker
author2 Jan A. Bergstra
John Tucker
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container_title Entropy
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container_issue 1
container_start_page 31
publishDate 2025
institution Swansea University
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publisher MDPI AG
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department_str School of Mathematics and Computer Science - Computer Science{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Mathematics and Computer Science - Computer Science
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description Classic formulae for entropy and cross-entropy contain operations 0 and log2 that are not defined on all inputs. This can lead to calculations with problematic subexpressions such as 0 log2 0 and uncertainties in large scale calculations; partiality also introduces complications in logical analysis. Instead of adding conventions or splitting formulae into cases, we create a new algebra of real numbers with two symbols ±∞ for signed infinite values and a symbol named ⊥ for the undefined. In this resulting arithmetic, entropy, cross-entropy, Kullback–Leibler divergence, and Shannon divergence can be expressed without concerning any further conventions. The algebra may form a basis for probability theory more generally.
published_date 2025-01-02T08:26:21Z
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