Constructions of Solid Hulls

摘要

For each concrete category (K, U) an extension LIM (K, U) is constructed and under certain 'smallness conditions' it is proved that LIM (K, U) is a solid hull of (K, U), i.e., the least finally dense solid extension of (K, U). A full subcategory of Top_2 is presented which does not have a solid hull.