Topology in a Category: Compactness


Abstract: In a category with a subobject structure and a closure operator, we provide a categorical theory of compactness and perfectness which yields a number of classical results of general topology as special cases, including the product theorems by Tychonoff and Frolik, the existence of Stone-Cech compactifications, both for spaces and maps, and the Henriksen-Isbell characterization of perfect maps of Tychonoff spaces. Applications to other categories yield, among other things, an alternative proof for the productivity of categorically compact groups.