A Topological Proof of the Archimedean Axiom for Archimedean Copulas
Victory Idowu
TL;DR
This work establishes a topological proof of the Archimedean axiom for Archimedean copulas in the presence of non-continuous distributions. By employing C-volume $V_C$ and recursive volumes $V_C^n(u)$, the authors show the sequence $f_n(u)=C(u,f_{n-1}(u))$ decreases to 0 for any $u\in(0,1)$, ensuring the Archimedean axiom holds without assuming continuity. The key contribution is a rigorous demonstration that the Archimedean property extends to discrete and mixed distributions via a partitioned, limit-based argument, with convergence governed by topological properties of $V_C$. This broadens the applicability of Archimedean copulas and clarifies the role of topological volumes in dependence modeling for noncontinuous settings.
Abstract
Archimedean copulas are a popular type of copulas in which a variant of the Archimedean axiom apply. We provide a topological proof of the Archimedean Axiom which is applicable for non-continuous distribution functions.
