Ranking Functions for Vector Addition Systems

Vector addition systems are an important model in theoretical computer science and have been used for the analysis of systems in a variety of areas. Termination is a crucial property of vector addition systems and has received considerable interest in the literature. In this paper we give a complete method for the construction of ranking functions for vector addition systems with states. The interest in ranking functions is motivated by the fact that ranking functions provide valuable additional information in case of termination: They provide an explanation for the progress of the vector addition system, which can be reported to the user of a verification tool, and can be used as certificates for termination. Moreover, we show how ranking functions can be used for the computational complexity analysis of vector addition systems (here complexity refers to the number of steps the vector addition system under analysis can take in terms of the given initial vector)

On the expressive power of communication primitives in parameterised systems

The final publication is available via https://doi.org/10.1007/978-3-662-48899-7_22.We study foundational problems regarding the expressive power of parameterised systems. These (infinite-state) systems are composed of arbitrarily many finite-state processes that synchronise using a given communication primitive, i.e., broadcast, asynchronous rendezvous, broadcast with message loss, pairwise rendezvous, or disjunctive guards. With each communication primitive we associate the class of parameterised systems that use it. We study the relative expressive power of these classes (can systems in one class be simulated by systems in another?) and provide a complete picture with only a single question left open. Motivated by the question of separating these classes, we also study the absolute expressive power (e.g., is the set of traces of every parameterised system of a given classAustrian Science Funds (FWF) Austrian National Research Network (RiSE)Vienna Science and Technology Fund (WWTF

Foundations of Software Science and Computation Structures

This open access book constitutes the proceedings of the 23rd International Conference on Foundations of Software Science and Computational Structures, FOSSACS 2020, which took place in Dublin, Ireland, in April 2020, and was held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The 31 regular papers presented in this volume were carefully reviewed and selected from 98 submissions. The papers cover topics such as categorical models and logics; language theory, automata, and games; modal, spatial, and temporal logics; type theory and proof theory; concurrency theory and process calculi; rewriting theory; semantics of programming languages; program analysis, correctness, transformation, and verification; logics of programming; software specification and refinement; models of concurrent, reactive, stochastic, distributed, hybrid, and mobile systems; emerging models of computation; logical aspects of computational complexity; models of software security; and logical foundations of data bases.