This article is written by two researcher from MIT and concludes, after giving mathematical models and experimental evidence, that in a dynamic world such as the software industry or consulting industry, firms may have plenty of incentive to innovate without patents and patents may constrict complementary innovation. It concludes that copyright protection for software programs (which has gone through its own evolution over the last decade) may have achieved a better balance than patent protection. This new model suggests another, different rationale for narrow patent breadth than the recent economic literature on this subject.
A mathematical model describing the economic effects of sofware patents and a concept for solving some of the problems: the distinction between copyright and useright.