Selected contributions from the Open Source Software Certification (OpenCert) Workshops

We present to you this special issue dedicated to the 2nd, 3rd and 4th editions of the International Workshop on Foundations and Techniques for Open Source Software Certification (OpenCert) held in 2008 (Milan, Italy), 2009 (York, UK) and 2010 (Pisa, Italy) respectively. This is a compilation of a selected set of extended papers presented at these workshops. OpenCert provides for a unique venue advancing the state of the art in the analysis and assurance of open source software with an ultimate aim of achieving certification and standards. The dramatic growth in open source software over recent years has provided for a fertile ground for fundamental research and demonstrative case studies. Over the years, OpenCert has enabled a thriving community, small but focused, examining issues ranging from certification to security and safety analysis for applications areas as diverse as railways, aviation, knowledge management, sustainable development, and the open source developers community