Computer chess breakthroughs and imitations

This new series of articles, by Dr. Søren Riis, here, and here, and here is of general interest and does not require chess knowledge.  They are an excellent case study in innovation, IP, reverse engineering, incentives to copy, market leadership, and other currently important concepts.  Excerpt:

This program was immediately thought to be a very close derivative of Rybka because its solving of test positions was extremely similar. But, beyond the objective measures of similarity testing, Strelka had to have been a reverse-engineered Rybka derivative because, at the time, a new program of such strength and manifest similarity in its playing style could hardly have come from anywhere else. Thus a very public precedent was established: someone had reverse-engineered a closed-source program with impunity.