From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function

We establish a correspondence between Lorenz curves and Pickands dependence functions, thereby reframing the construction of any bivariate extreme-value copula as an inequality problem. We discuss the conditions under which a Lorenz curve generates a closed-form Pickands model, considerably expandin...

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Main Authors: Pasquale Cirillo, Andrea Fontanari
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/13/13/2047
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author Pasquale Cirillo
Andrea Fontanari
author_facet Pasquale Cirillo
Andrea Fontanari
author_sort Pasquale Cirillo
collection DOAJ
description We establish a correspondence between Lorenz curves and Pickands dependence functions, thereby reframing the construction of any bivariate extreme-value copula as an inequality problem. We discuss the conditions under which a Lorenz curve generates a closed-form Pickands model, considerably expanding the small set of tractable parametrizations currently available. Furthermore, the Pickands measure-generating function <i>M</i> can be written explicitly in terms of the quantile function underlying the Lorenz curve, providing a constructive route to model specification. Finally, classical inequality indices like the Gini coincide with scale-free, rotation-invariant indices of global upper-tail dependence, thereby complementing local coefficients such as the upper tail dependence index <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>λ</mi><mi>U</mi></msub></semantics></math></inline-formula>.
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spelling doaj-art-2409d2d8ad5c4dc39e49dba40fcd75912025-08-20T03:50:17ZengMDPI AGMathematics2227-73902025-06-011313204710.3390/math13132047From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence FunctionPasquale Cirillo0Andrea Fontanari1ZHAW School of Management and Law, Theaterstrasse 17, 8401 Winterthur, SwitzerlandOptiver BV, Strawinskylaan 3095, 1077ZX Amsterdam, The NetherlandsWe establish a correspondence between Lorenz curves and Pickands dependence functions, thereby reframing the construction of any bivariate extreme-value copula as an inequality problem. We discuss the conditions under which a Lorenz curve generates a closed-form Pickands model, considerably expanding the small set of tractable parametrizations currently available. Furthermore, the Pickands measure-generating function <i>M</i> can be written explicitly in terms of the quantile function underlying the Lorenz curve, providing a constructive route to model specification. Finally, classical inequality indices like the Gini coincide with scale-free, rotation-invariant indices of global upper-tail dependence, thereby complementing local coefficients such as the upper tail dependence index <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>λ</mi><mi>U</mi></msub></semantics></math></inline-formula>.https://www.mdpi.com/2227-7390/13/13/2047Lorenz curvepickands dependence functionextreme-value copulainequality measurestail dependence
spellingShingle Pasquale Cirillo
Andrea Fontanari
From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
Mathematics
Lorenz curve
pickands dependence function
extreme-value copula
inequality measures
tail dependence
title From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
title_full From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
title_fullStr From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
title_full_unstemmed From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
title_short From Inequality to Extremes and Back: A Lorenz Representation of the Pickands Dependence Function
title_sort from inequality to extremes and back a lorenz representation of the pickands dependence function
topic Lorenz curve
pickands dependence function
extreme-value copula
inequality measures
tail dependence
url https://www.mdpi.com/2227-7390/13/13/2047
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AT andreafontanari frominequalitytoextremesandbackalorenzrepresentationofthepickandsdependencefunction