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.     

Alternating-time stream logic for multi-agent systems

Constraint automata have been introduced to provide a uniform operational model for specifying service interfaces of components, the network that yields the glue code for the components, and the operational behavior of the composite system. Constraint automata have been used as the basis for equivalence checking and model checking temporal logical properties. This paper presents a multi-player semantics for constraint automata which serves to reason about controllability, interaction and cooperation facilities of individual components or coalitions of components in a given network. We introduce a temporal logic framework, called alternating-time stream logic, that combines classical features of alternating-time logic (ATL) for concurrent games with special operators for specifying regular conditions on the data streams in the network and on the write and read operations at the I/O-ports of the components. Since constraint automata support any kind of synchronous and asynchronous peer-to-peer communication, the resulting game structure is non-standard and requires a series of nontrivial adaptations to the semantics and verification algorithms for classical alternating-time approaches.     

A general knowledge mediation infrastructure for multi-agent systems

Intelligent decision making needs to be equipped with broader knowledge in order to enhance the decision quality. Knowledge for decision making can be categorized as domain specific and general. Applying domain knowledge in intelligent systems is not new, but applying general knowledge to support business decision making is a possible way to obtain an edge over competitors. For this reason, the paper focuses primarily on designing a general knowledge mediation infrastructure (GKMI) which supports the use of general knowledge from multiple heterogeneous sources, and provides an unified access point for typical multi-agent systems (MAS) to access that knowledge. The finite state automaton (FSA) is used to model and analyze the commonsense inference ability of GKMI. By carrying out two use cases of GKMI for MAS development and operation the effectiveness of this infrastructure is examined.     

Model checking temporal knowledge and commitments in multi-agent systems using reduction

Though modeling and verifying Multi-Agent Systems (MASs) have long been under study, there are still challenges when many different aspects need to be considered simultaneously. In fact, various frameworks have been carried out for modeling and verifying MASs with respect to knowledge and social commitments independently. However, considering them under the same framework still needs further investigation, particularly from the verification perspective. In this article, we present a new technique for model checking the logic of knowledge and commitments (CTLKC⁺). The proposed technique is fully-automatic and reduction-based in which we transform the problem of model checking CTLKC⁺ into the problem of model checking an existing logic of action called ARCTL. Concretely, we construct a set of transformation rules to formally reduce the CTLKC⁺ model into an ARCTL model and CTLKC⁺ formulae into ARCTL formulae to get benefit from the extended version of NuSMV symbolic model checker of ARCTL. Compared to a recent approach that reduces the problem of model checking CTLKC⁺ to another logic of action called GCTL¹, our technique has better scalability and efficiency. We also analyze the complexity of the proposed model checking technique. The results of this analysis reveal that the complexity of our reduction-based procedure is PSPACE-complete for local concurrent programs with respect to the size of these programs and the length of the formula being checked. From the time perspective, we prove that the complexity of the proposed approach is P-complete with regard to the size of the model and length of the formula, which makes it efficient. Finally, we implement our model checking approach on top of extended NuSMV and report verification results for the verification of the NetBill protocol, taken from business domain, against some desirable properties. The obtained results show the effectiveness of our model checking approach when the system scales up.     

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.     

Cut-free sequent systems for temporal logic

Currently known sequent systems for temporal logics such as linear time temporal logic and computation tree logic either rely on a cut rule, an invariant rule, or an infinitary rule. The first and second violate the subformula property and the third has infinitely many premises. We present finitary cut-free invariant-free weakening-free and contraction-free sequent systems for both logics mentioned. In the case of linear time all rules are invertible. The systems are based on annotating fixpoint formulas with a history, an approach which has also been used in game-theoretic characterisations of these logics.     

A sound and complete fuzzy temporal constraint logic.

In this work, we define an extended fuzzy temporal constraint logic (EFTCL) based on possibilistic logic. EFTCL allows us to handle fuzzy temporal constraints between temporal variables and, therefore, enables us to express interrelated events through fuzzy temporal constraints. EFTCL is compatible with a theoretical temporal reasoning model: the fuzzy temporal constraint networks (FTCN). The syntax, the semantics and the deduction and refutation theorems for EFTCL are similar to those defined for the sound and noncomplete fuzzy temporal constraint logic (FTCL). In this paper, a resolution principle for performing inferences which take these constraints into account is proposed for EFTCL. Moreover, we prove the soundness and the completeness of the refutation by resolution in EFTCL.     

Model checking multi-agent systems with logic based Petri nets

We introduce a class of Petri nets, simple logic Petri nets (SLPN), that are based on logical expressions. We show how this type of nets can be efficiently mapped into logic programs with negation: the corresponding answer sets describe interleaved executions of the underlying nets (Theorem 1). The absence of an answer set indicates a deadlock situation. We also show how to correctly model and specify AgentSpeak agents and multi-agent systems with SLPN’s (Theorem 2). Both theorems allow us to solve the task of model checking AgentSpeak multi-agent systems by computing answer sets of the obtained logic program with any ASP system.     

A temporal blackboard for a multi-agent environment

The multi-agent system paradigm emerges as an interesting approach in the Knowledge Based System (KBS) field, when distributed problem-solving techniques are required for solving problems that can be represented as a collection of groups of cooperating intelligent individuals. A key concept in the multi-agent systems is the interaction between agents. On the other hand time plays a crucial role in a wide range of KBS applications. Temporal reasoning and representations consists of formalizing the notion of time and providing means to represent and reason about the temporal aspects of knowledge. This paper presents a framework for agent communication based on the blackboard paradigm which is able to manage temporal information, and it provides its multiple access and coherence management protocols.     

Quantified epistemic logics for reasoning about knowledge in multi-agent systems

We introduce quantified interpreted systems, a semantics to reason about knowledge in multi-agent systems in a first-order setting. Quantified interpreted systems may be used to interpret a variety of first-order modal epistemic languages with global and local terms, quantifiers, and individual and distributed knowledge operators for the agents in the system. We define first-order modal axiomatisations for different settings, and show that they are sound and complete with respect to the corresponding semantical classes.The expressibility potential of the formalism is explored by analysing two MAS scenarios: an infinite version of the muddy children problem, a typical epistemic puzzle, and a version of the battlefield game. Furthermore, we apply the theoretical results here presented to the analysis of message passing systems [R. Fagin, J. Halpern, Y. Moses, M. Vardi, Reasoning about Knowledge, MIT Press, 1995; L. Lamport, Time, clocks, and the ordering of events in a distributed system, Communication of the ACM 21 (7) (1978) 558–565], and compare the results obtained to their propositional counterparts. By doing so we find that key known meta-theorems of the propositional case can be expressed as validities on the corresponding class of quantified interpreted systems.     

On the soundness,completeness and applicability of the logic of knowledge and communicative commitments in multi-agent systems

Benthem’s correspondence theory is one of the most important tools of the theory of modal logics developed in the last three decades. Correspondence theory, a subfield of the model theory, reflects a systematic study of relations between classes of frames and modal language. In this paper, we use correspondence theory for modal logics to solve a problem not addressed yet in the literature, namely the soundness and completeness of a logic combining two different, yet related modalities: agents’ knowledge and commitments. The paper proves the soundness and completeness of this logic called CTLKC⁺. This work is highly significant as it proves that combining the two agents’ modalities resulted in a consistent logic that can be used to design reliable systems. The methodology is as follows: we develop a set of reasoning postulates (axioms) that reflect the interaction between agents’ knowledge and social commitments in multi-agent system (MAS) using the CTLKC⁺ logic and correspond them to certain classes of frames. In particular, we first give a name, formalization and meaning for each postulate. Then, we correspond the postulates to certain classes of frames and provide the required proofs. Thereafter, we present a discussion that illustrates the importance of the proposed postulates in MASs using a concrete application example called the NetBill protocol taken from the business domain. Finally, we show how the postulates were addressed in the literature. The existence of such a correspondence allows us to prove that the logic generated by any subset of these postulates is sound and complete with respect to models that are based on the corresponding frames. The ultimate goal of this paper is to further assess the logic of knowledge and commitments (CTLKC⁺) from a new perspective (i.e., the soundness and completeness). Consequently, this work advances the literature of logics in MASs and closes a gap that has not been explored before.     

An efficient trust estimation model for multi-agent systems using temporal difference learning

In multi-agent system (MAS) applications, teamwork among the agents is essential as the agents are required to collaborate and pool resources to execute the given tasks and complete the objectives successfully. A vital part of the collaboration is sharing of information and resources in order to optimize their efforts in achieving the given objectives. Under such collaborative environment, trust among the agents plays a critical role to ensure efficient cooperation. This study looks into developing a trust evaluation model that can empirically evaluate the trust of one agent on the other. The proposed model is developed using temporal difference learning method, incorporating experience gained through interactions into trust evaluation. Simulation experiments are conducted to evaluate the performance of the developed model against some of the most recent models reported in the literature. The results of the simulation experiments indicate that the proposed model performs better than the comparison models in estimating trust more effectively.

     

A knowledge assimilation method for logic databases

In this paper we consider a deductive question-answering system for relational databases as a logic database system, and propose a knowledge assimilation method suitable for such a system. The concept of knowledge assimilation for deductive logic is constructed in an implementable form based on the notion of amalgamating object language and metalanguage. This concept calls for checks to be conducted on four subconcepts, provability, contradiction, redundancy, independency, and their corresponding internal database updates. We have implemented this logic database knowledge assimilation program in PROLOG, a logic programming language, and have found PROLOG suitable for knowledge assimilation implementation.     

A decidable first-order logic for knowledge representation

Decidable first-order logics with reasonable model-theoretic semantics have several benefits for knowledge representation. These logics have the expressive power of standard first order logic along with an inference algorithm that will always terminate, both important considerations for knowledge representation. Knowledge representation systems that include a faithful implementation of one of these logics can also use its model-theoretic semantics to provide meanings for the data they store. One such logic, a variant of a simple type of first-order relevance logic, is developed and its properties described. This logic, although extremely weak, does capture a non-trivial and well-motivated set of inferences that can be entrusted to a knowledge representation system.This is a revised and much extended version of a paper of the same name that appears in the Proceedings of the Ninth International Joint Conference on Artificial Intelligence, Los Angeles, California, 1985.     

A framework for simulating real-time multi-agent systems

In this paper, we describe an implementation of use in demonstrating the effectiveness of architectures for real-time multi-agent systems. The implementation provides a simulation of a simplified RoboCup Search and Rescue environment, with unexpected events, and includes a simulator for both a real-time operating system and a CPU. We present experimental evidence to demonstrate the benefit of the implementation in the context of a particular hybrid architecture for multi-agent systems that allows certain agents to remain fully autonomous, while others are fully controlled by a coordinating agent. In addition, we discuss the value of the implementation for testing any models for the construction of real-time multi-agent systems and include a comparison to related work.

Mining parametric temporal logic properties in model-based design for cyber-physical systems

International Journal on Software Tools for Technology Transfer - One of the advantages of adopting a model-based development process is that it enables testing and verification at early stages of...     

Verification of reactive systems using temporal logic with clocks

This paper presents a framework for the specification and verification of timing properties of reactive systems using Temporal Logic with Clocks (TLC). Reactive systems usually contain a number of parallel processes, therefore, it is essential to study and analyse each process based on its own local time. TLC is a temporal logic extended with multiple clocks, and it is in particular suitable for the specification of reactive systems. In our framework, the behavior of a reactive system is described through a formal specification; its timing properties, including safety and liveness properties, are expressed by TLC formulas. We also propose several demonstration techniques, such as an application of local reasoning and deriving fixed-time rules from the proof system of TLC, for proving that a reactive system meets its temporal specification. Under the proposed framework, the timing properties of a reactive system can therefore be directly reasoned about from the formal specification of the system.     

基于粗糙描述逻辑的不精确时态知识表示研究

在粗糙描述逻辑基础上扩充不精确时态关系,以满足不精确时态知识表示与推理的需要。首先给出了粗糙集及粗糙描述逻辑的相关概念;接着通过定义粗糙时态描述逻辑不精确时态关系,扩展了粗糙描述逻辑中具体域,并给出了可靠性和完备性证明;最后通过实际例子说明粗糙时态描述逻辑的知识表示和应用,结果表明扩展后的粗糙时态描述逻辑可以实现不精确时态知识的表示与推理。     

基于强相关逻辑的不精确应急时态知识表示

在强相关逻辑基础上扩展不精确时态关系,以满足不精确应急时态知识表示与推理的需要。给出了粗糙集及强相关逻辑的相关概念;通过定义不精确时态关系扩展了强相关逻辑,形成了粗糙时态强相关逻辑,给出了可靠性和完备性证明;通过实际例子说明粗糙时态强相关逻辑的知识表示和应用。结果表明扩展后的粗糙时态强相关逻辑可以实现不精确时态知识的表示与推理。