Welcome to the Fourth International Workshop on Practical Applications of Stochastic Modelling, held in conjunction with MASCOTS. PASM is organised as a friendly and inclusive event at which to share interesting and novel applications and developments in modelling theory. We strive to maintain an air of informality to the workshop which we hope fosters discussion and potential collaboration. This volume is the 'on-the-day' proceedings for delegates only. In common with previous PASM workshops, the official proceedings will be published later in Elsevier's Electronic Notes in Theoretical Computer Science. If you wish to cite a paper from the workshop, please use the ENTCS citation which we will place on the PASM website when it is available. The workshop organisers would like to take this opportunity to extend their thanks to Michael Mislove, executive editor of ENTCS, for his continued support for PASM.
This is the fourth time PASM has been held, previous events were held in London in 2004, Newcastle in 2005, Palma de Mallorca in 2008. On each occasion PASM has been collocated with a different host conference. This year we are delighted to be associated with MASCOTS for the first time. We would like to thank Tony Field for inviting us and for his help in organising PASM. Jeremy, Will and Nigel would like to thank Nick for doing all the practical work. The organisation of an event like PASM is a team effort and we've learnt to choose our team carefully. Particular thanks must go to the programme committee, who thoroughly refereed all the submissions and made some difficult choices easier by their detailed comments.
Finally we would like to thank you, the authors and delegates. Without you there would be no papers, no presentations, no questions, no discussion and consequently no PASM. This is your workshop, we hope you enjoy it!
Jeremy Bradley, Nick Dingle, William Knottenbelt and Nigel Thomas
Information from pubs.doc.ic.ac.uk/pasm2009-proceedings.