Dependence Structure and Symmetry of Huang-Kotz Fgm Distributions and Their Extensions

An extension of FGM class of bivariate distributions with given marginals is presented. For Huang-Kotz FGM distributions some theorems characterizing symmetry and conditions for independence are obtained. The new family of distributions allows us to achieve correlation between the components greater than 0.5

Special Precovers in Cotorsion Theories

A cotorsion theory is defined as a pair of classes Ext-orthogonal to each other. We give a hereditary condition (HC) which is satisfied by the (flat, cotorsion) cotorsion theory and give properties satisfied by arbitrary cotorsion theories with an HC. Given a cotorsion theory with an HC, we consider the class of all modules having a special precover with respect to the first class in the cotorsion theory and show that this class is closed under extensions. We then raise the question of whether this class is resolving or coresolving