Offensive - Economic model

Sequential Innovation, Patents, and Imitation - James Bessen, Research on Innovation and Visiting Schika, MIT Sloan School of Management & Eric Maskin, Institute for Advanced Study and Princeton University - Novemmber 1999, Revised July 2002 - http://www.researchinnovation.org/patent.pdf

Discoveries are not isolated but based on former discoveries (sequential process)

Imitation becomes a spur to innovation, whereas strong patents become an impediment.

Competition increases market size

Imitation promotes innovation and strong patents (long lived patents of broad scope) inhibit it.

Competition can reduce the profit from an invention but subsequent market expansion leads to signigicant further benefits

A firm may well be better off if other firms imitate and compete against it. Although imitation reduces the firm's current profit, it raises the probability of further innovations, which improve the firm's futur profit.