Towards a sound semantics for dynamic fault trees

In this article, we study the semantics of dynamic fault trees and related formalisms. We suggest that there are actually three mechanisms at work in dynamic fault trees: first, changes of states due to occurrences of events, second bottom-up propagations of values as in static fault trees, and third top-down propagations of demands of activations of components. We propose a direct translation of dynamic fault trees into guarded transitions systems, the underlying mathematical model of the AltaRica 3.0 modeling language. This encoding provides a good basis for our study. We discuss also assessment algorithms at hand in light of this translation.