Generalized Hadamard differentiability of the copula mapping and its applications

Abstract: We consider the copula mapping, which maps a joint cumulative distribution function to the corresponding copula. Its Hadamard differentiablity was shown in van der Vaart and Wellner (1996), Fermanian et al. (2004) and (under less strict assumptions) in B\"ucher and Volgushev (2013). This differentiability result has proved to be a powerful tool to show weak convergence of empirical copula processes in various settings using the functional delta method. We state a generalization of the Hadamard differentiability results that simplifies the derivations of asymptotic expansions and weak convergence of empirical copula processes in the presence of covariates. The usefulness of this result is illustrated on several applications which include a multidimensional functional linear model, where the copula of the error vector describes the dependency between the components of the vector of observations, given the functional covariate.