It is often argued that implicit taxation on continued activity of elderly workers is responsible for the widely observed trend towards early retirement. In a world of laissez-faire or of first-best efficiency, there would be no such implicit taxation. The point of this paper is that when...

We study competition in two sided markets with common network externality rather than with the standard inter-group e¤ects. This type of externality occurs when both groups benefit, possibly with different intensities, from an increase in the size of one group and from a decrease in the size of...