TAIC PART 2007 and Mutation 2007 special issue editorial

Software testing is a topic of growing importance because of the central role it plays in so many aspects of software engineering, both preand post-delivery. There is strong empirical evidence (Glass, 2002; Leffingwell and Widrig, 2003) that deficient testing of both functional and non-functional properties is one of the major sources of software and system errors. In 2002, NIST estimated the cost of software failure to the US economy at $60,000,000,000; an astonishing 0.6% of GDP (NIST, 2002). The same report found that more than one third of these costs of software failure could be eliminated by an improved testing infrastructure. As these data reveal, the importance of work on software testing and its potential impact on the global economy is hard to overstate. TAIC PART 2007 was a unique software testing event that combined aspects of a conference, a workshop and a retreat. Through this unique blend of attributes the event brought together industrialists and academics in an environment that sought to promote meaningful collaboration on problems in software testing. Among computer science and software engineering activities, software testing is a perfect candidate for such a union of academic and industrial minds, because the problems thrown up by software testing touch upon so many academic research concerns, while the implications of advances in research can have such wide ranging and far reaching implications for industry. Testing research combines elements of computability and algorithmic complexity theory with the mathematics and pragmatics of representations such as finite state machines, flow graphs, call graphs and dependence graphs. It involves disciplines that cover the spectrum of software engineering activity, from psychology, through engineering to pure mathematics and even philosophy. This astonishing breadth and depth have made the problems of software testing appealing to academics for several decades. However, as industrialists know, testing software is unlike any other kind of engineering testing activity. It will not suffice to test at two ends of a spectrum of values, in order to infer properties inbetween. Software systems exhibit discrete behaviour and may combine this with non-determinism and emergent behaviour. No other engineering artefact is more closely integrated with the human mind, leading to complex hybrid systems that involve software, human judgement and, sometimes, political, legal and social processes. As technology matures, the planet is increasingly becoming enveloped in a ‘software skin’ of interconnected, interdependent processes, under which software controls and regulates both the ‘blood flow’ of information and the ‘mechanisms of action’. TAIC PART 2007 was funded by the Engineering and Physical Sciences Research Council (the EPSRC). The EPSRC is the UK’s primary funding body for research in Science and Engineering. The EPSRC evaluated TAIC PART on completion by peer review and gave