Lecture Series 2025 - IEEE SMC Italy Chapter - Partially observed discrete-event systems under unreliable information

#Opacity #DiscreteEventSystems #SilentEvent #UnreliableInformation

Speaker: Prof. Carla Seatzu - University of Cagliari

Abstract:  In this talk we focus on discrete event systems whose events occurrence is not fully observable. Indeed, there exist events that are silent (no observation is produced when they occur) and events that are indistinguishable (different events that are simultaneously enabled produce the same observation). In this framework different problems may be investigated. Here the attention is devoted to state estimation and two other problems strictly related to it, namely, fault diagnosis and opacity verification.  Some results relative to the case of reliable observations are first recalled. Then, the case of unreliable observations is considered. In particular, in the case of state estimation and fault diagnosis, the unreliability may originate from malicious attacks, which are common in cyber-physical systems.  The attack typically consists in a corruption of the observations produced by the occurrence of the events. In more detail, some observations may be erased and fake observations may be inserted.  This clearly affects the state estimation and the fault diagnosis, and robustness criteria should be imposed. On the contrary, in the case of opacity, the corruption of the observations may be performed by the system operator with the aim of guaranteeing opacity with respect to a given secret to a system that is not opaque under reliable observations. Criteria to appropriately corrupt the observations will be mentioned.  The talk will be concluded with a discussion of open problems in this framework.