Gabriele Oliva, Stefano Panzieri and Roberto Setola, "Fuzzy Input-Output Inoperability Model," 6th International Conference on Critical Information Infrastructure Security (CRITIS2011), 2011.
In this paper the Input Output Inoperability Model (IIM) is extended in order to manage situations where the impact of the external perturbation, e.g., accidental failure or terroristic attack, can not be sharply estimated. To this end we introduce a Fuzzy version of the IIM model, namely FIIM, where the level of inoperability of each infrastructure is described via fuzzy variables, hence characterized by a set of values with different level of believeness. A formal approach is derived, showing that convergence of the solution can be inferred, under suitable conditions, on the base of the stability properties of the crisp version of the system. Finally a case study on the Italian Critical Infrastructures is provided.