1. Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. E-mail: mallios@cmu.edu
2. Institute for Software Research, Carnegie Mellon University, Pittsburgh, PA, USA. E-mail: lbauer@cmu.edu
3. Computer Science Department, Carnegie Mellon University, Pittsburgh, PA, USA. E-mail: dilsun@cs.cmu.edu
4. Istituto di Informatica e Telematica, National Research Council, Pisa, Italy. E-mail: Fabio.Martinelli@iit.cnr.it
5. Newcastle University, Newcastle, UK. E-mail: charles.morisset@newcastle.ac.uk