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SUMMARY:Reasoning about Software Safety Integrity and Assurance - Tim Kell
 y\, University of York
DTSTART:20110223T141500Z
DTEND:20110223T151500Z
UID:TALK28690@talks.cam.ac.uk
CONTACT:Stephen Clark
DESCRIPTION:With increasing amounts of software being used within safety c
 ritical applications\, there is growing concern as to how designers and re
 gulators can justify that this is software is sufficiently safe for use.  
 At the system level\, it is reasonable and sensible to talk in terms of ri
 sk mitigation\, and to establish arguments that the probability of occurre
 nce of identified risks is acceptably low.   Whilst it is not difficult to
  cascade these risk-based requirements to software\, it becomes extremely 
 difficult to reason about software system failure probabilistically (for a
 ll but trivial examples).  Instead\, qualitative arguments and evidence (c
 oncerning the satisfaction of specific software safety properties and requ
 irements) are instead typically offered up.  These can be test-based argum
 ents\, or analytic (e.g.) proof-based arguments.   However\, these argumen
 ts (even when deductive reasoning is employed) cannot be established with 
 absolute certainty.  There remains epistemic uncertainty surrounding such 
 approaches:  Has the software (and its interface with the real world) been
  modeled adequately?  Can the abstractions used be justified?  Are the too
 ls used in the process qualified?  This talk will examine the problems of 
 exchanging safety arguments concerning real-world risk (associated with al
 eatoric uncertainty) for issues of confidence associated with software saf
 ety arguments (associated with epistemic uncertainty).  We’ll present th
 ese concerns in the context of structured (but informal) argumentation app
 roaches used within software safety justifications\, and the guidance that
  we have developed for safety-critical industries as part of the Software 
 Systems Engineering Initiative (www.ssei.org.uk).\n\n\nBiography\n\nDr Tim
  Kelly is a Senior Lecturer within the Department of Computer Science at t
 he University of York. He is Academic Theme Leader for Dependability withi
 n the Ministry of Defence funded Software Systems Engineering Initiative\,
  and was Deputy Director of the Rolls-Royce Systems and Software Engineeri
 ng University Technology Centre. His research interests include safety cas
 e management\, software safety analysis and justification\, software archi
 tecture safety\, certification of adaptive and learning systems\, and the 
 dependability of “Systems of Systems”. He has supervised a number of r
 esearch projects in these areas with funding and support from the European
  Union\, EPSRC\, Airbus\, Railway Safety and Standards Board\, Rolls-Royce
  BAE Systems and the Ministry of Defence. Dr Kelly has published over 140 
 papers on safety-critical systems development and assurance issues.\n\n
LOCATION:Lecture Theatre 1\, Computer Laboratory
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