Galois Theories - Paperbackby Francis Borceux (Author), George Janelidze (Author) Starting from the classical finite dimensional Galois theory of fields, this book develops Galois theory in a much more general context. The authors first formalize the categorical context in which a general Galois theorem holds, and then give applications to Galois theory for commutative rings, central extensions of groups, the topological theory of covering maps and a Galois theorem for toposes.