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Yan Kim

Publications and source records attributed to Yan Kim.

6 recordsLinked to original sources
arXiv2025

Practical Abstractions for Model Checking Continuous-Time Multi-Agent Systems

Model checking of temporal logics in a well established technique to verify and validate properties of multi-agent systems (MAS). However, practical model checking requires input models of manageable size. In this paper, we extend the model reduction method by variable-based abstraction, proposed recently by Jamroga and Kim, to the verification of real-time systems and properties. To this end, we define a real-time extension of MAS graphs, extend the abstraction procedure, and prove its correctness for the universal fragment of Timed Computation Tree Logic (TCTL). Besides estimating the theoretical complexity gains, we present an experimental evaluation for a simplified model of the Estonian voting system and verification using the Uppaal model checker.

cs.MA↗
arXiv2023

Practical Model Reductions for Verification of Multi-Agent Systems

Formal verification of intelligent agents is often computationally infeasible due to state-space explosion. We present a tool for reducing the impact of the explosion by means of state abstraction that is (a) easy to use and understand by non-experts, and (b) agent-based in the sense that it operates on a modular representation of the system, rather than on its huge explicit state model.

cs.MA↗
arXiv2022

Verification of the Socio-Technical Aspects of Voting: The Case of the Polish Postal Vote 2020

Voting procedures are designed and implemented by people, for people, and with significant human involvement. Thus, one should take into account the human factors in order to comprehensively analyze properties of an election and detect threats. In particular, it is essential to assess how actions and strategies of the involved agents (voters, municipal office employees, mail clerks) can influence the outcome of other agents' actions as well as the overall outcome of the election. In this paper, we present our first attempt to capture those aspects in a formal multi-agent model of the Polish presidential election 2020. The election marked the first time when postal vote was universally available in Poland. Unfortunately, the voting scheme was prepared under time pressure and political pressure, and without the involvement of experts. This might have opened up possibilities for various kinds of ballot fraud, in-house coercion, etc. We propose a preliminary scalable model of the procedure in the form of a Multi-Agent Graph, and formalize selected integrity and security properties by formulas of agent logics. Then, we transform the models and formulas so that they can be input to the state-of-art model checker Uppaal. The first series of experiments demonstrates that verification scales rather badly due to the state-space explosion. However, we show that a recently developed technique of user-friendly model reduction by variable abstraction allows us to verify more complex scenarios.

cs.MA↗
arXiv2022

Practical Abstraction for Model Checking of Multi-Agent Systems

Model checking of multi-agent systems (MAS) is known to be hard, both theoretically and in practice. A smart abstraction of the state space may significantly reduce the model, and facilitate the verification. In this paper, we propose and study an intuitive agent-based abstraction scheme, based on the removal of variables in the representation of a MAS. This allows to do the reduction without generating the global model of the system. Moreover, the process is easy to understand and control even for domain experts with little knowledge of computer science. We formally prove the correctness of the approach, and evaluate the gains experimentally on models of a postal voting procedure.

cs.MA↗
arXiv2020

Model Checkers Are Cool: How to Model Check Voting Protocols in Uppaal

The design and implementation of an e-voting system is a challenging task. Formal analysis can be of great help here. In particular, it can lead to a better understanding of how the voting system works, and what requirements on the system are relevant. In this paper, we propose that the state-of-art model checker Uppaal provides a good environment for modelling and preliminary verification of voting protocols. To illustrate this, we present an Uppaal model of Pr\^et \`a Voter, together with some natural extensions. We also show how to verify a variant of receipt-freeness, despite the severe limitations of the property specification language in the model checker.

cs.CR↗