why is a gumbel copula useful? can the gambel copula be used for multivariable why is an archimedean copula useless why archimedean copulas are useful what is the lumbel copula archimedean copulas useful what are archimedean copulas used for is a gumbel copula useful is the gambel copula useful are archimedean copulas useful are copulas useful what is the use of copulas in math why are gumbel copulas useless what quadrature is a humbel copula useful for why are copulas useful is a gumbel copula used for multivariate are elliptical copulas useful are archimedean copulas useful for multivariate analysis why is archimedean copula useful which is better the humbel copula or vine copula