Intentions, an integral part of the mental state of an agent, play an important role in

Of special interest in formal verification are safety properties, which assert that the system always stays within some allowed region. Proof rules for the verification of safety properties have been developed in the proof-based approach to verification, making verification of safety properties simpler than verification of general properties. In this paper we consider model checking of safety properties. A computation that violates a general linear property reaches a bad cycle, which witnesses the violation of the property. Accordingly, current methods and tools for model checking of linear properties are based on a search for bad cycles. A symbolic implementation of such a search involves the calculation of a nested fixed-point expression over the system's state space, and is often impossible. Every computation that violates a safety property has a finite prefix along which the property is violated. We use this fact in order to base model checking of safety properties on a search for ...

Verifying that a temporal logic specification satisfies a temporal property requires some form of theorem proving. However, although proof procedures exist for such logics, many are either unsuitable for automatic implementation or only deal with small fragments of the logic. In this thesis the algorithms for, and strategies to guide, a fully automated temporal resolution theorem prover are given, proved correct and evaluated. An approach to applying resolution, a proof method for classical logics suited to mechanisation, to temporal logics has been developed by Fisher. The method involves translation to a normal form, classical style resolution within states and temporal resolution over states. It has only one temporal resolution rule and is therefore particularly suitable as the basis of an automated temporal resolution theorem prover. As the application of the temporal resolution rule is the most costly part of the method, involving search amongst graphs, different algorithms on w...

The formalization of multi-agent autonomous systems requires a rich ontology for capturing a variety of collective behaviours and a powerful semantics for distinguishing between collective agents having, executing, and jointly intending a plan. In this paper, we introduce the notion of social agents and social plans. A definition of joint intentions is provided that avoids some of the problems encountered by previous formalizations. In particular, it models cooperation by requiring that agents adopt a joint goal and a joint plan of action before forming a joint intention. The paper also stresses the planning capability of agents and outlines a process for means-end reasoning by multiple agents. 1 Introduction Situated agents are systems embedded in dynamic environments; they continuously sense their environment and effect changes to it by performing actions. These agents have to balance the time they devote to thinking against the time they take acting. Also they need to balance the...

In this paper, we examine the relationships between beliefs, goals, and intentions. In particular, we consider the formalization of the Asymmetry Thesis as proposed by Bratman [ 1987 ] . We argue that the semantic characterization of this principle determines if the resulting logic is capable of handling other important problems, such as the side-effect problem of belief-goal-intention interaction. While Cohen and Levesque's [ 1990 ] formalization faithfully models some aspects of the asymmetry thesis, it does not solve all the side-effect problems; on the other hand the formalization provided by Rao and Georgeff [ 1991 ] solves all the side-effect problems, but only models a weak form of the asymmetry thesis. In this paper, we combine the intuition behind both these approaches and provide a semantic account of the asymmetry thesis, in both linear-time and branching-time logics, for solving many of these problems. 1 Introduction Formalizations of intentions and their relationships w...

In this chapter, we present a hierarchy of infinite-state systems based on the primitive operations of sequential and parallel composition; the hierarchy includes a variety of commonly-studied classes of systems such as context-free and pushdown automata, and Petri net processes. We then examine the equivalence and regularity checking problems for these classes, with special emphasis on bisimulation equivalence, stressing the structural techniques which have been devised for solving these problems. Finally, we explore the model checking problem over these classes with respect to various linear- and branching-time temporal logics.

We study the decidability of the model checking problem for linear and branching time logics, and two models of concurrent computation, namely Petri nets and Basic Parallel Processes. 1 Introduction Most techniques for the verification of concurrent systems proceed by an exhaustive traversal of the state space. Therefore, they are inherently incapable of considering systems with infinitely many states. Recently, some new methods have been developed in order to at least palliate this problem. Using them, several verification problems for some restricted infinite-state models have been shown to be decidable. These results can be classified into those showing the decidability of equivalence relations [8, 9, 24, 26], and those showing the decidability of model checking for different modal and temporal logics. In this paper, we contribute to this second group. The model checking problem has been studied so far for three infinite-state models: context-free processes, pushdown processes, and...

The study of computational agents capable of rational behaviour has received a great deal of attention in recent years. A number of theoretical formalizations for such multiagent systems have been proposed. However, most of these formalizations do not have a strong semantic basis nor a sound and complete axiomatization. Hence, it has not been clear as to how these formalizations could be used in building agents in practice. This paper explores a particular type of multi-agent system, in which each agent is viewed as having the three mental attitudes of belief (B), desire (D), and intention (I). It provides a family of multi-modal branching-time BDI logics with a semantics that is grounded in traditional decision theory and a possible-worlds framework, categorizes them, provides sound and complete axiomatizations, and gives constructive tableaubased decision procedures for testing the satisfiability and validity of formulas. The computational complexity of these decision procedures is n...

. There is a growing need for reliable methods of designing correct reactive systems such as computer operating systems and air traffic control systems. It is widely agreed that certain formalisms such as temporal logic, when coupled with automated reasoning support, provide the most effective and reliable means of specifying and ensuring correct behavior of such systems. This paper discusses known complexity and expressiveness results for a number of such logics in common use and describes key technical tools for obtaining essentially optimal mechanical reasoning algorithms. However, the emphasis is on underlying intuitions and broad themes rather than technical intricacies. 1 Introduction There is a growing need for reliable methods of designing correct reactive systems. These systems are characterized by ongoing, typically nonterminating and highly nondeterministic behavior. Examples include operating systems, network protocols, and air traffic control systems. There is w...

Agent-Oriented Software Engineering (AOSE) is an emerging paradigm within industry that offers much potential of the management of the increasing levels of complexity inherent within modern software systems. For this paradigm to gain widespread acceptance, it is vital that we develop comprehensive frameworks that support the development and deployment of agent-oriented applications. This thesis contributes to this through the development of a four-tier development framework entitled the Agent Factory System. This framework combines an agent programming language that is founded upon a formal agent theory of commitment; a run-time environment that delivers a set of services that support the deployment of agent-oriented applications written in this programming language; an integrated development environment that delivers a toolkit that supports the development of these applications; and a development methodology that promotes a structure approach to the use of this toolkit. Finally, we evaluate the Agent Factory System from the context of various real-world