A Formal Specification and Verification of Normative Multi-agent Systems by DisCSP

This article describes first steps towards the formal specification and verification of multi-agent systems, through the use of temporal belief logics. The article first describes Concurrent METATEM, a multi-agent programming language, and then develops a logic that may be used to reason about Concurrent METATEM systems. The utility of this logic for specifying and verifying Concurrent METATEM systems is demonstrated through a number of examples. The article concludes with a brief discussion on the wider implications of the work, and in particular on the use of similar logics for reasoning about multi-agent systems in general.

We develop a logic-based framework for formal specification and algorithmic verification of homogeneous and dynamic concurrent multi-agent transition systems. Homogeneity means that all agents have the same available actions at any given state and the actions have the same effects regardless of which agents perform them. The state transitions are therefore determined only by the vector of numbers of agents performing each action and are specified symbolically, by means of conditions on these numbers definable in Presburger arithmetic. The agents are divided into controllable (by the system supervisor/controller) and uncontrollable, representing the environment or adversary. Dynamicity means that the numbers of controllable and uncontrollable agents may vary throughout the system evolution, possibly at every transition. As a language for formal specification we use a suitably extended version of Alternating-time Temporal Logic, where one can specify properties of the type “a coalition of (at least) n controllable agents can ensure against (at most) m uncontrollable agents that any possible evolution of the system satisfies a given objective gamma″, where gamma is specified again as a formula of that language and each of n and m is either a fixed number or a variable that can be quantified over. We provide formal semantics to our logic {mathcal {L}}_{textsc {hdmas}} and define normal form of its formulae. We then prove that every formula in {mathcal {L}}_{textsc {hdmas}} is equivalent in the finite to one in a normal form and develop an algorithm for global model checking of formulae in normal form in finite HDMAS models, which invokes model checking truth of Presburger formulae. We establish worst case complexity estimates for the model checking algorithm and illustrate it on a running example.

In this paper we present a logic to provide a framework for the formal specification of multiagent real-time systems which allows explicit reasoning about the actions of agents, the nondeterministic model of interaction between agents and environment, the cooperation and competition of agents and the reaction time limits of a system. The logic combines Propositional Dynamic Logic PDL and Alternating-time Temporal Logic ATL and extends the formalism with reaction time constraints. We introduce a multiagent system abstract model and show how the logic can be used to specify the model properties.

Hybrid systems such as those that combine 3D virtual worlds and organization based multiagent systems add new visual and communication features for multiuser applications. The design of such hybrid and dynamic systems is a challenging task. In this paper, we propose a system that can automatically generate a 3D virtual world (VW) from an organization based multiagent system (MAS) specification that establishes the activities participants can engage on. Both shape grammar and virtual world paradigms inspired us to propose a Virtual World Grammar (VWG) to support the generation process of a virtual world design. A VWG includes semantic information about both MAS specification and shape grammar elements. This information, along with heuristics and validations, guides the VW generation producing functional designs. To support the definition and execution of a Virtual World Grammar, we have developed a so named Virtual World Builder Toolkit (VWBT). We illustrate this process by generating a 3D visualization of a virtual institution from its specification.

During requirement specification process of software development activities, many existing systems or business process requirements have been captured using natural language or specialized tools such as UML. However, the capturing of informal requirements into formalized properties has not been taken into attention by software developers due to time and budget constraints. It is critical for the informally captured requirements to be formally specified in order to perform system verification. Formal verification checks whether a system model meets the formal specifications while validation checks whether the developed system fulfills its intended purpose. Therefore, in this paper, we present our studies of formal verification of multi agent system using model checking approach. We have utilized model checking tool in order to execute the formal verification procedures based on a particular basic theory to verify certain kind of properties of requirement specifications. We show an example of how model checking tool could support the verification of Universiti Teknologi Malaysia (UTM) multi agent online application system and conclude that the propose model checking approach will benefit multi agent system.

Autonomous robotic systems are complex, hybrid, and often safety-critical; this makes their formal specification and verification uniquely challenging. Though commonly used, testing and simulation alone are insufficient to ensure the correctness of, or provide sufficient evidence for the certification of, autonomous robotics. Formal methods for autonomous robotics have received some attention in the literature, but no resource provides a current overview. This short paper summarises the contributions of Luckcuck 2019, which surveys the state-of-the-art in formal specification and verification for autonomous robotics.

Formal specification and verification of complex IoT systems’ behavior can efficiently improve the systems’ correctness and reliability. This paper presents an enhanced time behavior protocol to specify real-time components’ timed interaction behaviors in IoT systems. The protocol model bound event tokens with time consumption constraint information according to requirements of practical applications, and time-related operators are added into the model language. Visualization and verification method for composited behavior is given. An application example is introduced, and the experimental results show that the enhanced time behavior protocol-based model can be used easily to specify, visualize, and verify IoT systems’ interaction behavior and timing constraint information.

In complex systems, multiple aspects interact and influence each other. A vast number of entities are present in the system. Traditional modeling and simulation techniques fail to capture interactions between loosely coupled aspects of a complex distributed system. The objective of this work is to extend a Holonic methodology by using a formal specification language based on two formalisms: Generalized Stochastic Petri Net (GSPN) and Z language. Such a specification style facilitates the modeling of organizations and the interactions between them with both reactive and functional aspects. We illustrate the suitability of our generic approach by applying it to a Distributed Industrial Maintenance Company.

In the recent years, several formal approaches to the specification of normative multi-agent systems (MASs) and artificial institutions have been proposed. The aim of this article is to advance the state of the art in this area by proposing an approach in which a normative MAS is conceived to be autonomous, in the sense that it is able to create, maintain and eventually change its own institutions by itself, without the intervention of an external designer in this process. In our approach the existence and the dynamics of an institution (norms, rules, institutional facts, etc.) are determined by the (individual and collective) acceptances of its members, and its dynamics depends on the dynamics of these acceptances. In order to meet this objective, we propose the logic AL (Acceptance Logic) in which the acceptance of a proposition by the agents qua members of an institution is introduced. Such propositions are true w.r.t. an institutional context and correspond to facts that are instituted in an attitude-dependent way. The second part of the article is devoted to the logical characterization of some important notions in the theory of institutions. We provide a formalization of the concept of constitutive rule, expressed by a statement of the form ‘X counts as Y in the context of institution x’. Then, we formalize the concepts of obligation and permission (so called regulative rules). In our approach, constitutive rules and regulative rules of a certain institution are attitude-dependent facts which are grounded on the acceptances of the members of the institution.

The lack of formalism and rigor in existing multi-agents models often leads to ambiguities and different interpretations. Those weaknesses combined with the inherent complexity of multi-agents systems generate many problems in their development process. Using formal notations to specify multi-agents systems’ behavior makes it possible to produce precise description. This also offers a better support to their verification and validation process. The Maude language, based on rewriting logic, presents a rich notation supporting formal specification and implementation of concurrent systems. In this paper, we demonstrate the feasibility and the interest of formalizing the behavior of DIMA model’s agents with the Maude language. The elaborated formal approach captures the inherent aspects of a DIMA model. The generated Maude descriptions have been validated using the platform supporting this language. Moreover, the proposed approach is generic and extensible. It offers, in particular, the advantage of being applicable to all multi-agents systems based on DIMA architecture and presents interesting extension possibilities.

Normative systems are a widely used framework to coordinate interdependent activities in multi-agent systems. Most research in this area has focused on how to compute normative systems that effectively accomplish a coordination task, as well as additional criteria such as synthesising norms that do not over-regulate a system, and the emergence of norms that remain stable over time. We introduce a framework for the synthesis of stable normative systems that are sufficient and necessary for coordination. Our approach is based on ideas from evolutionary game theory. We simulate multi-agent systems in which useful norms are more likely to prosper than useless norms. We empirically show the effectiveness of our approach in a simulated traffic domain.

While waiting for the millennium: Formal specification and verification of concurrent systems now

This book is a celebration of Leslie Lamport's work on concurrency, interwoven in four-and-a-half decades of an evolving industry: from the introduction of the first personal computer to an era when parallel and distributed multiprocessors are abundant. His works lay formal foundations for concurrent computations executed by interconnected computers. Some of the algorithms have become standard engineering practice for fault tolerant distributed computing - distributed systems that continue to function correctly despite failures of individual components. He also developed a substantial body of work on the formal specification and verification of concurrent systems, and has contributed to the development of automated tools applying these methods. Part I consists of technical chapters of the book and a biography. The technical chapters of this book present a retrospective on Lamport's original ideas from experts in the field. Through this lens, it portrays their long-lasting impact. The chapters cover timeless notions Lamport introduced: the Bakery algorithm, atomic shared registers and sequential consistency; causality and logical time; Byzantine Agreement; state machine replication and Paxos; temporal logic of actions (TLA). The professional biography tells of Lamport's career, providing the context in which his work arose and broke new grounds, and discusses LaTeX - perhaps Lamport's most influential contribution outside the field of concurrency. This chapter gives a voice to the people behind the achievements, notably Lamport himself, and additionally the colleagues around him, who inspired, collaborated, and helped him drive worldwide impact. Part II consists of a selection of Leslie Lamport's most influential papers. This book touches on a lifetime of contributions by Leslie Lamport to the field of concurrency and on the extensive influence he had on people working in the field. It will be of value to historians of science, and to researchers and students who work in the area of concurrency and who are interested to read about the work of one of the most influential researchers in this field.

We present logical formalism for specification of multiagent systems, which allows us to formalize explicitly the notion of agent’s action, a nondeterministic method for interaction with environment, a cooperation mechanism of agents, ant time constraints on system reaction. Introducing new constructions for time constraint descriptions and offering thereby the natural formalism for specification of a multiagent system mathematical model, the method extends capabilities of dynamic logic PDL and altering-time temporal logic ATL. The model checking problem for the formalism offered is solvable in polynomial time.

Reactive Multi-Agent system (RMAS) has emerged as an attractive technology for the design and implementation of distributed and cooperative systems. The RMAS main challenge is how to clearly identify its local and global behavior. Several approaches have been introduced to deal with behavioral specification of RMAS. However, there is a lack in the specification and verification process that facilitates understanding the system from goals identification that the system expects to achieve to formal verification of system properties. In this paper, we are interested to the specification problem of Reactive Multi-Agent System (RMAS) for both individual and collective behavior by taking into account two modes of specification: normal mode and fault-tolerance mode. To do so, we propose a method called BECAMEDA (Behavioral SpEcification and VerifiCAtion of RMAS based on E-MDRA) for the specification and verification of reactive Multi-agent system based on the MDRA (Multi-Decisional Reactive Agent) models. The MDRA specifies the reactive agent behavior by highlighting the decisional aspect of the agent. The BECAMEDA method will be described throughout an example of Car Crisis Management.