40 Years of Computing at Newcastle
Department Technical Report Series No. 589
Subjective Safety Analysis for Software Development
J. Wang, A. Saeed and R. de Lemos
University of Newcastle upon Tyne. 1997.
Abstract
This paper presents a framework for subjective safety analysis of software requirements specifications for safety-critical systems. The framework incorporates fuzzy set modelling and evidential reasoning to assess the safety associated with safety requirements specifications. Fuzzy set theory is used to model each safety rule and evidential reasoning is employed to synthesize the information produced. Three basic parameters - failure likelihood, consequence severity and failure consequence probability are used to analyse a safety rule (a basic element of a software requirements specification) in terms of membership functions. The subjective safety description associated with the safety rule is then mapped back to a scale of pre-defined safety expressions which are also characterised in terms of membership functions. Such a mapping results in the production of the safety evaluation associated with the safety rule, expressed in terms of the degrees to which the subjective safety description belongs to the pre-defined safety expressions. Such degrees represent uncertainty in the safety evaluation associated with the safety rule. The information produced for all safety rules can then be synthesized using an evidential reasoning approach to obtain the safety evaluation associated with the safety requirements specifications. The developed framework is capable of dealing with multiple safety analysts who make judgements on each safety rule.
Department Technical Report Series - 1997
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Technical Report Abstract No. 589, 30 June 1997