The fundamental theorem of Galois theory

For arbitrary categories $C$ and $X$ and an arbitrary functor $I\colon C\to X$ the author introduces the notion of an $I$-normal object and proves a general type of fundamental theorem of Galois theory for such objects. It is shown that the normal extensions of commutative rings and central extensions of multi-operator groups are special cases of $I$-normal objects.
Bibliography: 14 titles.