Does Firefox obey Lehman’s Laws of software Evolution?

Maintenance, bug fixes and software updates are necessary to every software project in order to keep it competitive in the software market. Lehman [2] called this process the evolution of a software system and has found eight patterns describing the evolution process for software systems. Michael Godfrey and Qiang Tu [7] provided a counter example against the patterns Lehman provides. They claimed that his laws do not necessarily apply to open source projects and provided Linux operating system kernel as an example. In this paper we tried to extend the study of Godfrey and Tu to Firefox, another well-known open source project, and try to find out if Lehman’s laws hold for Firefox or not. We also try to provide an improvement to Lehman’s laws which tries to fix the existing problems. 1