Verification of Unbounded Client-Server Systems with Distinguishable Clients

2026-02-26

AI Summary

This work addresses the challenge of verifying unbounded client-server systems with dynamically varying and distinguishable clients, a scenario where traditional model checking techniques fall short. To tackle this problem, the paper proposes a modeling approach based on ν-nets and introduces a first-order temporal logic, FOTL₁, specifically designed to precisely capture the dynamic behaviors of distinguishable clients. By integrating ν-nets with FOTL₁ and encoding the resulting framework into SMT solvers, the authors develop a bounded model checking (BMC) procedure that enables, for the first time, automated verification of such systems. The accompanying BMC tool has been open-sourced, significantly advancing the state of formal verification for unbounded concurrent systems.

Technology Category

• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories
• Multiagent Systems: Agreement, Argumentation & Negotiation
• Knowledge Representation and Reasoning: Automated Reasoning and Theorem Proving

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Virtualization and resource management in Web systems and infrastructures
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

Client-server systems are a computing paradigm in concurrent and distributed systems. We deal with unbounded client-server systems (UCS) where all clients are of the same type, interact with a single server and they may enter and exit the system dynamically. At any point in time, the number of clients is bounded, but their exact number is unknown and dynamic. To model these systems, simple Petri nets are not directly usable, so we use unbounded $ν$-nets. Owing to the distinguishability of clients in UCS, it is not straightforward to express their properties in LTL or CTL. To address this, we propose the logic $\mathsf{FOTL_1}$, a monodic fragment of Monadic First Order Temporal Logic (MFOTL). In this work, we provide the SMT encodings of $ν$-nets and $\mathsf{FOTL_1}$ to do Bounded Model Checking (BMC). We also build an accompanying open source tool to perform BMC of UCS.

Problem

• unbounded client-server systems
• distinguishable clients
• temporal logic verification
• dynamic concurrency
• formal verification

Innovation

• ν-nets
• FOTL₁
• Bounded Model Checking
• Client-Server Systems
• Monadic First-Order Temporal Logic