Using Subobservers to Synthesize Opacity-Enforcing Supervisors

TL;DR

This paper introduces the concept of subobservers to efficiently synthesize opacity-enforcing supervisors in discrete-event systems, significantly reducing computational complexity compared to traditional observer calculations.

Contribution

It extends the subautomaton concept to subobservers, enabling more practical and intuitive synthesis of opacity-enforcing supervisors with reduced computational effort.

Findings

Subobserver relationship simplifies observer computations.

Method reduces complexity in synthesizing opacity-enforcing supervisors.

Demonstrated effectiveness under realistic assumptions.

Abstract

In discrete-event system control, the worst-case time complexity for computing a system's observer is exponential in the number of that system's states. This results in practical difficulties since some problems require calculating multiple observers for a changing system, e.g., synthesizing an opacity-enforcing supervisor. Although calculating these observers in an iterative manner allows us to synthesize an opacity-enforcing supervisor and although methods have been proposed to reduce the computational demands, room exists for a practical and intuitive solution. Here we extend the subautomaton relationship to the notion of a subobserver and demonstrate its use in reducing the computations required for iterated observer calculations. We then demonstrate the subobserver relationship's power by simplifying state-of-the-art synthesis approaches for opacity-enforcing supervisors under realistic assumptions.