Transforming opacity verification to nonblocking verification in modular systems

We consider the verification of current-state and K-step opacity for systems modeled as interacting non-deterministic finite-state automata. We describe a new methodology for compositional opacity verification that employs abstraction, in the form of a notion called opaque observation equivalence, and that leverages existing compositional nonblocking verification algorithms. The compositional approach is based on a transformation of the system, where the transformed system is nonblocking if and only if the original one is current-state opaque. Furthermore, we prove that $K$-step opacity can also be inferred if the transformed system is nonblocking. We provide experimental results where current-state opacity is verified efficiently for a large scaled-up system

Anticipatory Traffic Modeling and Route Guidance: A General Mathematical Formulation

https://deepblue.lib.umich.edu/bitstream/2027.42/154111/1/lafortune1990.pd

Stability analysis for combustion fronts traveling in hydraulically resistant porous media

We study front solutions of a system that models combustion in highly hydraulically resistant porous media. The spectral stability of the fronts is tackled by a combination of energy estimates and numerical Evans function computations. Our results suggest that there is a parameter regime for which there are no unstable eigenvalues. We use recent works about partially parabolic systems to prove that in the absence of unstable eigenvalues the fronts are convectively stable.Comment: 21 pages, 4 figure

Compositional and Abstraction-Based Approach for Synthesis of Edit Functions for Opacity Enforcement

This paper develops a novel compositional and abstraction-based approach to synthesize edit functions for opacity enforcement in modular discrete event systems. Edit functions alter the output of the system by erasing or inserting events in order to obfuscate the outside intruder, whose goal is to infer the secrets of the system from its observation. We synthesize edit functions to solve the opacity enforcement problem in a modular setting, which significantly reduces the computational complexity compared with the monolithic approach. Two abstraction methods called opaque observation equivalence and opaque bisimulation are first employed to abstract the individual components of the modular system and their observers. Subsequently, we propose a method to transform the synthesis of edit functions to the calculation of modular supremal nonblocking supervisors. We show that the edit functions synthesized in this manner correctly solve the opacity enforcement problem

Divergent stutter bisimulation abstraction for controller synthesis with linear temporal logic specifications

This paper proposes a method to synthesise controllers for systems with possibly infinite number of states that satisfy a specification given as an LTL\◦ formula. A common approach to handle this problem is to first compute a finite-state abstraction of the original state space and then synthesise a controller for the abstraction. This paper proposes to use an abstraction method called divergent stutter bisimulation to abstract the state space of the system. As divergent stutter bisimulation factors out stuttering steps, it typically results in a coarser and therefore smaller abstraction, at the expense of not preserving the temporal ‘‘next’’ operator. The paper leverages results about divergent stutter bisimulation from model checking and shows that divergent stutter bisimulation is a sound and complete abstraction method when synthesising controllers subject to specifications in LTL\◦