Integrating several formalisms in order to increase Fault Treesʹ modeling power

The Fault Tree (FT) is a widespread model in the field of Reliability, but its modeling power is very limited. Therefore, several FT extensions have been proposed in the literature, each introducing particular modeling primitives, but in a separate way. In this paper, we integrate the primitives coming from three relevant FT extensions (parametric, dynamic, and repairable FT), into the formalism called generalized FT (GFT). We define each primitive in such a way that it can be combined with any other one. This allows to compactly represent redundancies and symmetries of the system structure, set several kinds of dependency among the events, and model repair processes, in the same model. The paper provides also the analysis process for GFT models, based on the modular approach. In particular, we provide the conditions to detect modules, considering the presence of all the primitives. Besides modules, we exploit the parametric form also at the solution level, with the aim of reducing the cost of analysis.