Involutions on surfaces with and
arXiv:1007.5036
Abstract
We study surfaces of general type with and having an involution such that the bicanonical map of is not composed with . It is shown that, if is not rational, then is birational to an Enriques surface or it has Kodaira dimension and the possibilities for the ramification divisor of the covering map are described. We also show that these two cases do occur, providing an example. In this example has a hyperelliptic fibration of genus and the bicanonical map of is of degree onto a rational surface.
13 pages