Algorithms and Data Structures for Parametric Analysis of Real-Time Systems

Abstract

This document is intended to contribute to the area of validation and verification of communicating real time systems, with emphasis put on parametric reachability analysis of systems modeled using timed automata.Reachability analysis is a crucial aspect of validation and verification of software and hardware systems. The reachability analysis for real time systems is area that is studied by many researchers in academic and industrial communities. However, not much work has been done for systems, where time constraints are expressed using parameters. This is serious disproportion with real world, where specifications of most of the communication protocols or embedded software and hardware systems are indeed parameterized.This thesis presents a complete framework for forward and backward parametric reachability analysis. The solution presented here can be used as a base of algorithms for validation and verification of software and hardware real-time systems, modeled as timed automata with parameters. The results of the thesis can be easily applied to model checking or test generation tools and algorithms.The core idea of the thesis is a concept of Extended Difference Bound Matrix (EDBM). This is a data structure that stores relations between all system"s clocks and parameters. In contrast to Parametric DBM, that is the state-of-the-art data structure for parametric analysis, EDBM does not require storing constraints on clocks and constraints on parameters separately. This leads to significant benefits regarding memory consumption and time necessary to perform basic operations for symbolic analysis.The maturity of the solution was proven by implementation of a proof-of-concept tool and by experiments performed with modern communication protocol. The results show that even complex systems can be efficiently handled by the framework.