Essential Closures and Supports of Multivariate Copulas
  We generalize the notion of essential closures which is used in formulating a geometric necessary condition for a set to be the support of a multivariate copula. Furthermore, in some special cases, we derive an explicit formula of the support in terms of essential closures and obtain a stronger necessary condition. 
Pongpol Ruankong, Songkiat Sumetkijakan
math.ST math.PR stat.TH