Co-Frobenius corings and adjoint functors. (Q931654)

The authors study co-Frobenius corings and quasi-co-Frobenius corings over arbitrary base rings, and in particular over PF base rings. Several characterizations are given for the co-Frobenius and for the quasi-co-Frobenius properties, some of them new even in the coalgebra case. The main idea and tool is the construction of several Morita contexts and the interpretation of the (quasi)-co-Frobenius properties in terms of these contexts.