Panagiotis Kouvaros

Parameterised verification for multi-agent systems

We study the problem of verifying role-based multi-agent systems, where the number of components cannot be determined at design time. We give a semantics that captures parameterised, generic multi-agent systems and identify three notable classes that represent different ways in which the agents may interact among themselves and with the environment. While the verification problem is undecidable in general we put forward cutoff procedures for the classes identified. The methodology is based on the existence of a notion of simulation between the templates for the agents and the template for the environment in the system. We show that the cutoff identification procedures as well as the general algorithms that we propose are sound; for one class we show the decidability of the verification problem and present a complete cutoff procedure. We report experimental results obtained on MCMAS-P, a novel model checker implementing the parameterised model checking methodologies here devised.

Parameterised Verification of Data-aware Multi-Agent Systems

We introduce parameterised data-aware multiagent systems, a formalism to reason about the temporal properties of arbitrarily large collections of homogeneous agents, each operating on an infinite data domain. We show that their parameterised verification problem is semi-decidable for classes of interest. This is demonstrated by separately addressing the unboundedness of the number of agents and the data domain. In doing so we reduce the parameterised model checking problem for these systems to that of parameterised verification for interleaved interpreted systems. We illustrate the expressivity of the formal model by modelling English auctions with an unbounded number of bidders on unbounded data.

Symbolic Synthesis of Fault-Tolerance Ratios in Parameterised Multi-Agent Systems

We study the problem of determining the robustness of a multi-agent system of unbounded size against specifications expressed in a temporalepistemic logic. We introduce a procedure to synthesise automatically the maximal ratio of faulty agents that may be present at runtime for a specification to be satisfied in a multi-agent system. We show the procedure to be sound and amenable to symbolic implementation. We present an implementation and report the experimental results obtained on a number of protocols from swarm robotics.

Formal Verification of a Programmable Hypersurface

A metasurface is a surface that consists of artificial material, called metamaterial, with configurable electromagnetic properties. This paper presents work in progress on the design and formal verification of a programmable metasurface, the Hypersurface, as part of the requirements of the VISORSURF research program (HORIZON 2020 FET-OPEN). The Hypersurface design is concerned with the development of a network of switch controllers that are responsible for configuring the metamaterial. The design of the Hypersurface, however, has demanding requirements that need to be delivered within a context of limited resources. This paper shares the experience of a rigorous design procedure for the Hypersurface network, that involves iterations between designing a network and its protocols and the formal evaluation of each design. Formal evaluation has provided results that, so far, drive the development team in a more robust design and overall aid in reducing the cost of the Hypersurface manufacturing.

Verifying Fault-tolerance in Parameterised Multi-Agent Systems.

We develop a technique to evaluate the faulttolerance of a multi-agent system whose number of agents is unknown at design time. We present a method for injecting a variety of non-ideal behaviours, or faults, studied in the safety-analysis literature into the abstract agent templates that are used to generate an unbounded family of multiagent systems with different sizes. We define the parameterised fault-tolerance problem as the decision problem of establishing whether any concrete system, in which the ratio of faulty versus non-faulty agents is under a given threshold, satisfies a given temporal-epistemic specification. We put forward a sound and complete technique for solving the problem for the semantical set-up considered. We present an implementation and a case study identifying the threshold under which the alpha swarm aggregation algorithm is robust to faults against its temporal-epistemic specifications.