Where product innovation requires several complementary patents, fragmented property rights can limit firms' willingness to invest in R& D. We consider the research intensity in multiple simultaneous R& D contests and how it depends on whether firms already hold relevant patents as well as the...

The authors study conflict on multiple fronts. A defending player needs to successfully defend all fronts, and an attacker needs to win at only one. Multiple fronts result in a considerable disadvantage for the defending player, and even if there is a defense advantage at each of them, the...