If the Alliance Fits . . . : Innovation and Network Dynamics.

Network formation is often said to be driven by social capital considerations. A typical pattern observed in the empirical data on strategic alliances is that of small world networks: dense subgroups of firms interconnected by (few) clique-spanning ties. The typical argument is that there is social capital value both to being embedded in a dense cluster, and to bridging disconnected clusters. In this paper we develop and analyze a simple model of joint innovation where we are able to reproduce these features, based solely on the assumption that successful partnering demands some intermediate amount of similarity between the partners.