Biography
Prof. Wolf-Dieter Richter
Prof. Wolf-Dieter Richter
University of Rostock, Germany
Title: Distributions with different margins
Abstract: 
Since a long time, the big class of spherical distribution laws plays an important role in applied mathematics, in particular in statistics and multivariate distribution theory, see e.g. Fang, Kotz and Ng (1990). Due to this theory, stochastic representations of correspondingly distributed random vectors are an important analytical tool for mathematically analyzing many statistics and their distributions. The central role is played in spherical distribution theory by the uniform probability law on the Euclidean unit sphere. All one-dimensional marginal distributions of a multivariate spherical distribution are identical. There is, however, a need for considering multivariate distribution classes allowing for di fferent marginal distributions. An example of such type appears as a high risk limit law in Balkema and Embrechts (2007) and is discussed for dimension two as a particular case of the class of (p; q)-spherical distributions in Richter (2017). A specifi c notion of a non-Euclidean arc-length measure serves as the basis for constructing a generalized uniform distribution on (p; q)-circles. Here, we go a next step and extent the latter distribution class to dimension three. From the technical point of view, the key point for introducing the new stochastic representation is the suitable adoption of the notion of surface content for defining a generalized uniform distribution on a generalized sphere. This is done by extending the non-Euclidean arc-length measure on (p; q)-circles to a generalized surface content measure in the present three-dimensional situation.
Biography: 
Wolf-Dieter Richter is an Emeritus Professor at the Institute of Mathematics at the University of Rostock. His main areas of research are Mathematical Statistics and Exact and Asymptotic Distribution Theory, namely generalized central and non-central Chisquare, Student- and Fisher- distributions, non-linear regression, exact and asymptotic distributions of likelihood-ratio classi cation rules, quantile approximation, simulation, skewness-kurtosis adjusted decisions, Kullback-Leibler life time testing, geometric and stochastic representations of star-shaped (especially convex and radially concave as well as polyhedral contoured), skewed and directional distributions, exact statistical distributions under non-standard assumptions, statistics in p-generalized elliptically contoured sample distributions, limit theorems in multivariate moderate and large deviation theory as well as scale mixtures and generalized stochastic processes. He has a Ph.D. and a Habilitation in Mathematics at Technical University of Dresden, is a Fellow of the Alexander von Humboldt-Stiftung, is the supervisor of ten Ph.D. students, is an ISI Elected Member and an Associate Editor of the Journal of Statistical Distributions and Applications. He is a reviewer for several mathematical journals, had research stays in Vilnius, St.Petersburg, Moscow, Novosibirsk, Aarhus, Providence, Hong Kong, Warsaw, Sao Paulo, Santiago de Chile, Vasa, Merida, Guanajuato, Valparaiso and Nottingham and gave talks at many universities and conferences. In his work, he and his numerous co-workers developed and combined analytical and geometric methods for analyzing distributions, introduced antinorms and semi-antinorms, introduced the anti-support function, introduced new trigonometric functions and coordinates for making his new geometric disintegration method an efficient tool of mathematical work, established non- Euclidean uniform distributions on generalized spheres, and the ball number function whose values are normalizing constants of generating functions of multivariate densities. Wolf-Dieter Richter's Erdoes number is three and eight steps back in his path of dissertation advisors there is Pafnuty Lvovich Chebyshev.