12.01.14 - 17.01.14, Seminar 14031

Randomized Timed and Hybrid Models for Critical Infrastructures

Diese Seminarbeschreibung wurde vor dem Seminar auf unseren Webseiten veröffentlicht und bei der Einladung zum Seminar verwendet.

The exhibition "Fabian Treiber: Neun Minuten vor Vegas", opens during the seminar. All participants are cordially invited to join us at 7:30 p.m. on Tuesday, Januar 13, 2014 in the lobby of the new building (next to reception). Light refreshments will be served and Dagstuhl's Scientific Director, Professor Reinhard Wilhelm, will say a few words about the artist and his work.


The smooth functioning of (often hidden) information and communication technology infrastructures has become more and more important to our society and economy in recent years. These infrastructures play an ever-increasing role in other critical infrastructures such as the power grid and water and gas distribution networks, highly dynamic systems that include assets essential to the functioning of our society and economy. Users need to be able to trust that such systems will work unfailingly, but environmental uncertainties, security and physical attacks, and defects in physical devices pose serious threats to their reliable operation. It is thus important to ensure that critical infrastructures can survive catastrophic events.

Modeling critical infrastructures and developing methods in order to analyze their safety and dependability in the face of such failures and disasters is therefore of utmost importance. Survivability, or how quickly systems will reach acceptable service levels following a disaster, is especially important. However, both failure and repair processes are random and a probability distribution is needed to describe how they evolve over time.

Randomized timed models can take into account the dependency of such processes on time, and powerful techniques exist for their analysis. However, the area of critical infrastructures still lacks a modeling formalism that allows for the description of both discrete and continuous quantities. Examples of discrete quantities are the number of spare parts and the state of sensors, actuators, and information and communication technology components. Physical quantities, such as the amount of produced energy or the quality of the treated water in terms of temperature and pressure, naturally constitute continuous quantities.

Randomized hybrid models have been successfully applied to model safety-critical applications. Due to the flexible combination of discrete and continuous state components, randomized hybrid models appear as a natural choice for the accurate modeling of critical infrastructures. While some formalisms have been proposed for the analysis of randomized hybrid models, and the field is experiencing increased interest and activity, the industrial application that we are considering is far too large for state-of-the-art approaches: either they are applicable to specific applications only or they do not scale.

To date, most modeling in critical infrastructures has still been fairly "classical", using reliability block diagrams, fault-trees or simplistic stochastic Petri nets. While researchers from the critical infrastructures community could benefit from recent advances for randomized hybrid models and their formal analysis, existing algorithms are not yet readily applicable to the special kind of problems arising in this field.

Researchers from the fields of critical infrastructures, randomized timed models and randomized hybrid models clearly have much to gain by coming together to discuss these shared challenges. The critical infrastructures community can benefit from recent advances in formal methods for randomized models and researchers from the modeling communities can learn about the special kind of problems arising in this application field. This Dagstuhl Seminar aims to raise awareness for the advances and requirements in the different communities in academia and industry, and facilitate the development of well-suited algorithms and tools for the assessment of critical infrastructures.