On Implementing Real-time Specification Patterns Using Observers

TL;DR

This paper explores how to implement real-time specification patterns in formal verification using observers within the AGREE environment, addressing subtle challenges and demonstrating applicability to avionics systems.

Contribution

It introduces methods for accurately modeling real-time patterns with observers in AGREE, highlighting previously unaddressed challenges and validating the approach on a real-world system.

Findings

Observers can effectively model real-time specification patterns

Subtle challenges exist in accurately expressing real-time constraints

The approach is validated on an avionics system

Abstract

English language requirements are often used to specify the behavior of complex cyber-physical systems. The process of transforming these requirements to a formal specification language is often challenging, especially if the specification language does not contain constructs analogous to those used in the original requirements. For example, requirements often contain real-time constraints, but many specification languages for model checkers have discrete time semantics. Work in specification patterns helps to bridge these gaps, allowing straightforward expression of common requirements patterns in formal languages. In this work we demonstrate how we support real-time specification patterns in the Assume Guarantee Reasoning Environment (AGREE) using observers. We demonstrate that there are subtle challenges, not mentioned in previous literature, to express real-time patterns accurately using observers. We then demonstrate that these patterns are sufficient to model real-time requirements for a real-world avionics system.