Locally coalgebra-Galois extensions

Abstract

The paper introduces the notion of a locally coalgebra-Galois extension and, as its special case, a locally cleft extension. The necessary and sufficient conditions for a locally coalgebra-Galois extension to be a (global) coalgebra-Galois extension are stated. As an important special case, it is proven, that under not very restrictive conditions the gluing of two locally cleft extensions is a globally coalgebra-Galois extension. As an example, the quantum lens space of positive charge is constructed by gluing of two quantum solid tori.