One feature of the European patent system that is heavily criticized nowadays is related to its complex fragmentation and the induced cost burden for applicants. Once a patent is granted by the EPO, the assignee must validate (and often translate) it and pay the renewal fees to keep it in force...

Patent holders may choose to protect innovations with single patents or to develop portfolios of multiple, related inventions. We propose a simple decision-making model in which patent-holders may allocate resources to either expanding the number of related patents or investing in higher value...