Universal coextensions within a variety.
Universal concrete categories and functors
Universal expansion of semigroup varieties by regular involution.
Universal objects in quasiconstructs
The general theory of J’onsson-classes is generalized to strongly smooth quasiconstructs in such a way that it also allows the construction of universal categories. One example of the theory is the existence of a concrete universal category over every base category. Properties are given which are (under certain conditions) equivalent to the existence of homogeneous universal objects. Thereby, we disprove the existence of a homogeneous C-universal category. The notion of homogeneity is strengthened...