Choosing Effective Methods for Design Diversity. How to Progress from Intuition211 to Science

摘要

Design diversity is a popular defense against design faults in safety critical211u001esystems. Design diversity is at times pursued by simply isolating the development 211u001eteams of the different versions, but there are good reasons to believe that it is 211u001ebetter to 'force' diversity, by appropriate prescriptions to the teams. There are 211u001emany ways of forcing diversity. The literature, including standards and 211u001eguidelines, includes lists of such ways at the disposal of a project manager, 211u001ee.g. dictating different algorithms, different programming or specification 211u001elanguages, etc. Yet, managers who have to choose a cost-effective combination of 211u001ethese have little guidance except their own intuition. Unfortunately, intuition 211u001ehas often proven wrong when dealing with diversity. The authors argue the need 211u001efor more scientifically based recommendations, and outline the problems with 211u001eproducing them. The authors focus on what they think is the standard basis for 211u001emost recommendations: the belief that project decisions should be aimed at 211u001ecausing 'diversity' among the faults of the various versions, and that this 211u001ediversity will in turn decrease the risk of the versions failing together. The 211u001eauthors attempt to clarify what these beliefs mean, in which casees they may be 211u001ejustified and how they can be checked or disproved experimentally.