Preface

This volume contains the proceedings of the Twelfth Workshop on Quantitative Aspects of Programming Languages and Systems (QAPL 2014), held in Grenoble, France, on 12 and 13 April, 2014. QAPL 2014 was a satellite event of the European Joint Conferences on Theory and Practice of Software (ETAPS).

The central theme of the workshop is that of quantitative aspects of computation. These aspects are related to the use of physical quantities (storage space, time, bandwidth, etc.) as well as mathematical quantities (e.g. probability and measures for reliability, security and trust), and play an important (sometimes essential) role in characterising the behaviour and determining the properties of systems. Such quantities are central to the definition of both the model of systems (architecture, language design, semantics) and the methodologies and tools for the analysis and verification of the systems properties. The aim of this workshop is to discuss the explicit use of quantitative information such as time and probabilities either directly in the model or as a tool for the analysis of systems. In particular, the workshop focuses on:

• the design of probabilistic, real-time and quantum languages, and the definition of semantical models for such languages;
• the discussion of methodologies for the analysis of probabilistic and timing properties (e.g. se- curity, safety, scheduability) and of other quantifiable properties such as reliability (for hardware components), trustworthiness (in information security) and resource usage (e.g. worst-case mem- ory/stack/cache requirements);
• the probabilistic analysis of systems which do not explicitly incorporate quantitative aspects (e.g. performance, reliability and risk analysis);
• applications to safety-critical systems, communication protocols, control systems, asynchronous hardware, and to any other domain involving quantitative issues.

The history of QAPL starts in 2001, when its first edition was held in Florence, Italy, as a satellite event of the ACM Principles, Logics, and Implementations of high-level programming languages, PLI 2001. The second edition, QAPL 2004, was held in Barcelona, Spain, as a satellite event of ETAPS 2004. Since then, QAPL has become a yearly appointment with ETAPS. In the following years, QAPL was held in Edinburgh, Scotland (QAPL 2005), Vienna, Austria (QAPL 2006), Braga, Portugal (QAPL 2007), Budapest, Hungary (QAPL 2008), York, UK (QAPL 2009), Paphos, Cyprus (QAPL 2010), Saarbrücken, Germany (QAPL 2011), Tallinn, Estonia (QAPL 2012), and Rome, Italy (QAPL 2013).
The proceedings of the workshop editions upto and including 2009 are published as volumes in Electronic Notes in Theoretical Computer Science (ENTCS). The editions of 2010, 2011, 2012 and 2013 are published as volume 28, volume 57, volume 85 and volume 117 respectively, of the Electronic Proceedings in Theoretical Computer Science (EPTCS).
Three special issues of the journal of Theoretical Computer Science are dedicated to the QAPL 2004, QAPL 2006 and QAPL 2010 events, and are published in Volume 346(1), Volume 382(1) and Volume 413(1) respectively. A special issue of the journal of Theoretical Computer Science dedicated to QAPL 2011 and QAPL 2012 is about to be published, while the call for a new special issue on Theoretical Computer Science dedicated to QAPL 2013 and QAPL 2014 has been just announced.

The workshop programme included four QAPL keynote presentations: Oded Maler (Verimag, France): Timed Systems: The Unmet Challenge, Stephen Gilmore (University of Edinburgh, UK): Quantitative Aspects of Public Transport, Enrico Vicario (University of Firenze, Italy): Quantitative evaluation of concurrent systems with non-Markovian temporal parameters, and Nicolas Markey (LSV, CNRS & ENS Cachan, France): Robustness issues in timed automata.

Furthermore, the Program Committee of QAPL 2014 which comprised of:

• Alessandro Aldini, University of Urbino, Italy
• Christel Baier, Technical University of Dresden, Germany
• Ezio Bartocci, Technical University of Vienna, Austria
• Marco Bernardo, University of Urbino, Italy
• Nathalie Bertrand (Co-chair), Inria, France
• Luca Bortolussi (Co-chair), University of Trieste, Italy
• Tomas Brazdil, Masaryk University, Czech Republic
• Krishnendu Chatterjee, IST Vienna, Autria
• Kostas Chatzikokolakis, CNRS, France
• Taolue Chen, Oxford University, UK
• Pedro D'Argenio, University of Cordoba, Argentina
• Thao Dang, Verimag, France
• Josee Desharnais, Laval University, Canada
• Alessandra Di Pierro, University of Verona, Italy
• Vashti Galpin, University of Edinburgh, UK
• Tingting Han, RWTH Aachen University, Germany
• Holger Hermanns, Saarland University, Germany
• Radu Mardare, Aalborg University, Denmark
• Mieke Massink, Italian National Research Council - ISTI, Pisa, Italy
• Paulo Mateus, Technical University of Lisbon, Portugal
• Gethin Norman, University of Glasgow, UK
• David Parker, Oxford University, UK
• Anne Remke, University of Twente, the Netherlands
• Arnaud Sangnier, LIAFA, University Paris VII, France
• Jeremy Sproston, University of Turin, Italy
• Mariëlle Stoelinga, Twente University, Netherlands
• Mirco Tribastone, LMU Munich, Germany
• Herbert Wiklicky, Imperial College London, UK
• Verena Wolf, Saarland University, Germany

We would like to thank the QAPL steering committee for its support, the ETAPS 2014 organisers and furthermore all the authors, the invited speakers, the programme committee and the external referees for their valuable contributions.

May 2014

Nathalie Bertrand and Luca Bortolussi
Program Co-chairs