The goal of the Reliability, Optimisation and Uncertainties Labex DEFI Team is to study the interplay between recent uncertainty models and the optimisation of system reliabilities.

• Sébastien Destercke (Head)
• Mohammed Sallak

• Lanting Yu (PhD Student)

• Michael Poss (Lirmm)

• Nadia Ben Abdallah (Currently Post-doctorate researcher at NATO - La Spezia)

In the past decades, uncertainty theories and representations incompleteness (i.e., modelled by intervals) and variability (i.e., modelled by a probability distribution) have progressed to a maturity level allowing them to be applied to more and more complex problems. On the other hand, both the reliability and optimisation domains acknowledge the needs to model both aspects of uncertainty. As these three fields are essential tools to deal with systems of systems (both to ensure their efficiency and robustness), the aim of this projects is to deepen the foundational links between them, and to apply the obtained results to systems of systems. In particular, the following lines of research will be followed :

• Bridging stochastic and robust optimisation through the use of recent uncertainty representations, such as lower previsions or belief functions.
• Defining optimal robust designs of systems of systems in terms of reliability under different assumptions (severe uncertainty, partially known system dependencies, …)
• Use of optimisation techniques to make efficient inferences
• Multi-objective optimisation under uncertainty

• Lanting Yu (PhD student) “Designing systems with ill-known probabilities”
• Joseph Rocca (Master student - finished) “Determining sequences of optimal queries to reduce interval uncertainty”

• S. Destercke, M. Poss and M. Sallak “Reliability analysis with ill-known probabilities and dependencies” ICVRAM 2014, Liverpool
• N. Ben Abdallah, S. Destercke “Optimal expert elicitation to reduce interval uncertainty”, UAI 2015
• L. Yu, S. Destercke, M. Sallak “Comparing system reliabilities with ill-known probabilities”, IPMU 2016
• N. Ben Abdallah, S. Destercke, M. Sallak “Easy and optimal queries to reduce set uncertainty”, European Journal of Operational Research, 2016
• S. Ferson, M. Sallak, S. Destercke “Reliability analysis using confidence structures (C-boxes)”, in preparation