Title
The Frank inequality.
Abstract
We investigate a functional inequality for copulas that has emerged from our study of the comparison of a set of random variables pairwisely coupled by a same copula. Any copula satisfying this inequality is necessarily symmetric and radially symmetric. Moreover, any associative copula satisfying this inequality is a solution to the well-known Frank equation. For this reason, the inequality is coined the Frank inequality. We fully characterize the associative copulas that satisfy the Frank inequality: they turn out to be either Frank copulas or ordinal sums of a same Frank copula with equidistant idempotent elements. As a by-product, we observe that Frank copulas are super-additive on the unit square.
Year
DOI
Venue
2018
10.1016/j.fss.2017.03.017
Fuzzy Sets and Systems
Keywords
DocType
Volume
Associative copula,Frank copula,Frank equation,Frank inequality,Super-additivity,Radial symmetry
Journal
335
ISSN
Citations 
PageRank 
0165-0114
0
0.34
References 
Authors
0
2
Name
Order
Citations
PageRank
Bernard De Baets12994300.39
Hans De Meyer230542.39