Boolean Variables and Their Application in Fault Tree Analysis

4 Boolean Variables and Their Application in Fault Tree Analysis 

As already mentioned the fault tree represents the logical relations between the primary events (in what follows often denoted by component failures for the sake of simplicity) and the undesired (unwanted or top) event (in what follows often denoted by system failure for the sake of simplicity). The relations represented by the fault tree are deterministic. We arrive at probabilistic statements only if probabilities are assigned to the component failures. 

The logical relations can advantageously be represented if Boolean or binary variables are used for describing component and system states [30], i.e. 

56) N is the total number of components of the system. The system state is described analogously, i.e. 

Boolean or binary variables and the corresponding functions only adopt two values 0 or 1. 

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