Xiangyu Luo

A concurrent dynamic logic of knowledge, belief and certainty for multi-agent systems

This paper extends the logic of knowledge, belief and certainty from one agent to multi-agent systems, and gives a good combination between logic of knowledge, belief, certainty in multi-agent systems and actions that have concurrent and dynamic properties. Based on it, we present a concurrent dynamic logic of knowledge, belief and certainty for MAS, which is called CDKBC logic. Furthermore, a CDKBC model is given for interpreting this logic. We construct a CDKBC proof system for the logic and show that the proof system is sound and complete, and prove that the validity problem for the system is EXPTIME-complete.

Solving Sum and Product Riddle via BDD-Based Model Checking

We model the sum and product riddle in public announcement logic, which is interpreted on an epistemic Kripke model. The model is symbolically represented as a finite state program with n agents. A model checking method to the riddle is developed by using the BDD-based symbolic model checking algorithm for logic of knowledge we developed in [7]. The method is implemented by extending the model checker MCTK [7] and then the solution of the riddle is verified successfully.

Symbolic model checking the knowledge in Herbivore protocol

The importance of anonymity has increased over the past few years in many applications. Herbivore is a distributed anonymous communication system, providing private file sharing and messaging over the Internet. In this paper, we utilize MCTK to model the round protocol of the Herbivore system and verify the anonymity and other knowledge properties that the protocol should provide, where MCTK is an OBDD-based symbolic model checker for temporal logic of knowledge developed by us, under the semantics of interpreted systems with local propositions. We model the round protocol of the Herbivore system in MCTK under the assumption that all agents have perfect recall of all observations. We implement the round protocol of the Herbivore system in MCTK and another epistemic model checker MCK. The encouraging experimental results show the validity of our MCTK.

Observation-Based logic of knowledge, belief, desire and intention

We present a new model of knowledge, belief, desire and intention, called the interpreted KBDI-system model (or KBDI-model for short). The key point of the interpreted KBDI-system model is that we express an agent’s knowledge, belief, desire and intention as a set of runs (computing paths), which is exactly a system in the interpreted system model, a well-known agent model due to Halpern and his colleagues. Our KBDI-model is computationally grounded in that we are able to associate a KBDI-model with a computer program, and formulas, involving agents’ knowledge, belief, desire (goal) and intention, can be understood as properties of program computations. With KBDI-model, we have two different semantics to interpret our logic of knowledge, belief, desire and intention. Moreover, with respect to each semantics, we present a sound and complete proof system.

Model Checking Needham-Schroeder Security Protocol Based on Temporal Logic of Knowledge

Formal verification approaches can guarantee the correctness of security protocols. In this paper we take the well-known Needham-Schroeder public-key authentication protocol as an example, to show how we can apply the symbolic model checker for multiagent systems MCTK, which is developed by us, to the verification of security protocols. One temporal epistemic property is checked successfully both in the original version and the Lowes revised version of the Needham-Schroeder protocol. The experimental result shows that our method is an effective way to the verification of security protocol.

Quantified Coalition Logic for BDI-Agents: Completeness and Complexity

This paper introduces a multi-dimensional modal logic of Quantified Coalition Logic of Beliefs, Desires and Intentions (QCLBDI) to reason about how agents’ mental attitudes evolve by cooperation in game-like multi-agent systems. We present a complete axiomatic system of QCLBDI with the formal proof and show that the satisfiability for QCLBDI is PSPACE-complete, computationally no harder than that of CL.

The based-role PMI model for access control in large scale netware system

T Because of the complexity of netware and its enveroment, how to ensure security of large scale netware systems is a longstanding key problem. The access control is always one of the important guarantees of security of large scale netware systems. The paper introduces the general AC(attribute certificate) and the role specification AC and the role assignment AC, and discusses the role-based PMI architecture, then combines the role-based PMI architecture with the PKI architecture to present a new access control model based on role PMI. The model has advantages of flexibility, convenience, less storage space and less network consumption etc. At present, we are going to use the model in management information systems of the large scale netware to realize access control for systems.

A first-order coalition logic for BDI-agents

Coalition logic (CL) enables us to model the strategic abilities and specify what a group of agents can achieve whatever the other agents do. However, some rational mental attitudes of the agents are beyond the scope of CL such as the prestigious beliefs, desires and intentions (BDI) which is an interesting and useful epistemic notion and has spawned substantial amount of studies in multi-agent systems. In this paper, we introduce a first-order coalition BDI (FCBDI) logic for multi-agent systems, which provides a semantic glue that allows the formal embedding and interaction of BDI, coalition and temporal operators in a first-order language. We further introduce a semantic model based on the interpreted system model and present an axiomatic system that is proved sound and complete with respect to the semantics. Finally, it is shown that the computational complexity of its model checking in finite structures is PSPACE-complete.

Translation-based verification of Web services composition via ZING

BPEL4WS (BPEL for short) is a standard business process execution language for Web services composition. To formally verify the correctness and reliability of Web services compositions, we propose an Input/Output Labelled Transition System (I/OLTS) as the intermediate formal model, which is well adapted to model BPEL constructs and handle faults, events, terminations, message correlation and activities. To be able to automatically verify Web services compositions via a model checker, we first develop a translation procedure to translate BPEL language into I/OLTS, and then develop another translation procedure to translate the I/OLTS model into the input language of ZING, a software model checker developed by Microsoft. The translation-based verification process for Web services composition is illustrated by a case study.