Requirements, Claims and Evidence

Abstract

“The only way to get somewhere, you know, is to figure out where you are going before you go there” says the farmer to Rabbit in John Updike’s “Rabbit, Run” [101]. This common sense advice takes on a special meaning in the context of dependability, because the point of departure of the justification is also its destination. We regard a dependability justification as the set of arguments and evidence components which support a carefully selected set of requirements addressing the dependability of the operation of a computer-based system in a given environment, for instance an industrial plant. These requirements need careful attention; they are the raw material we start off with and also the properties we have to justify in the end.