This work presents several extensions to the Fault Tree [90] formalism used to build models oriented to the Dependability [103] analysis of systems. In this way, we increment the modelling capacity of Fault Trees which turn from simple combinatorial models to an high level language to represent more complicated aspects of the behaviour and of the failure mode of systems. Together with the extensions to the Fault Tree formalism, this work proposes solution methods for extended Fault
Trees in order to cope with the new modelling facilities. These methods are mainly based on the use of Stochastic Petri Nets. Some of the formalisms described in this work are already present in the literature;
for them we propose alternative solution methods with respect to the existing ones. Other formalisms are instead part of the original contribution of this work
