QUANTITATIVE ASSESSMENT MODELS FOR SOFTWARE SAFETY RELIABILITY/

Safety and reliability have become important software quality characte ristics in the development of safety-critical software systems. Howeve r, there are so far no quantitative methods for assessing a safety-cri tical software system in terms of safety/reliability characteristics. The metric of software safety is defined as the probability that condi tions that can lead to hazards do not occur. In this paper, we propose two stochastic models for software safety/reliability assessment: the data-domain dependent safety assessment model and the availability-re lated safety assessment model. These models focus on describing the ti me- or execution dependent behavior of software faults that can lead t o unsafe states when they cause software failures. Numerical examples are also provided for quantitative software safety assessment. (C) 199 8 Scripta Technica.