Reducing model checking commitments for agent communication to model checking ARCTL and GCTL*

Abstract

Social commitments have been extensively and effectively used to represent and model business contracts among autonomous agents having competing objectives in a variety of areas (e.g., modeling business processes and commitmentbased protocols). However, the formal verification of social commitments and their fulfillment is still an active research topic. This paper presents CTLC + that modifies CTLC, a temporal logic of commitments for agent communication that extends CTL logic to allow reasoning about communicating commitments and their fulfillment. The verification technique is based on reducing the problem of model checking CTLC + into the problem of model checking ARCTL (the combination of CTL with action formulae) and the problem of model checking GCTL * (a generalized version of CTL * with action formulae) in order to respectively use the extended NuSMV symbolic model checker and the CWB-NC automata-based model checker as a benchmark. We also prove that the reduction techniques are sound and the complexity of model checking CTLC + for concurrent programs with respect to the size of the components of these programs and the length of the formula is PSPACE-complete. This matches the complexity of model checking CTL for concurrent programs as shown by Kupferman et al. We finally provide two case studies taken from business domain along with their respective implementations and experimental results to illustrate the effectiveness and efficiency of the proposed technique. The first one is about the NetBill protocol and the second one considers the Contract Net protocol.

A Formal Verification Method of Obligation Policy in Multi-agent System

“…A social commitment SC is a public commitment made by an agent (called the debtor), and directed towards a set of agents (called creditor), indicating that some fact is true or some action will be performed [10]. Nowadays, social commitments have been extensively and effectively used in a variety of areas ranging from developing artificial institutions [11], verifying process communication [12], and modeling multi-agent interaction [13] and so on. The definition of social commitment as follows:…”

Verifying Multiagent-Based Web Service Compositions Regulated by Commitment Protocols

“…However, model checking the proposed logic is still an open problem. We extended CTL with modalities to represent and reason upon unconditional commitments and their fulfillments [4], [11]. The resulting logic is called CTLC.…”

“…The resulting logic is called CTLC. We then proceeded to verify the correctness of CTLC by developing symbolic algorithms needed for the new modalities [4] and by transforming the problem of model checking CTLC into the problems of model checking ARCTL (an extension of CTL with action formulae) and GCTL * (an extension of CTL * with action formulae) so that their model checkers (NuSMV and CWB-NC) are usable [11]. However, the semantics of other commitment actions, and conditional commitments are not addressed.…”

“…Thus, in our approach, the engineering of composed systems (MASs) means rigorously and declaratively specifying the interactions among multiagent-based web services by the way of commitment protocols. According to a declarative specification, commitment protocols are flexible, making them suitable for accommodating dynamic changes or exceptions, and can be directly verified [4], [11] without requiring the transformation into other formalisms. To express protocol properties being model checking, we use our branching-time temporal logic, called CTL cc , which extends computation tree logic (CTL) with temporal modalities for commitments and their fulfillments [10] (see Section IV).…”

“…To express protocol properties being model checking, we use our branching-time temporal logic, called CTL cc , which extends computation tree logic (CTL) with temporal modalities for commitments and their fulfillments [10] (see Section IV). We interpret CTL cc formulae using a temporal model, generated from our extended version of interpreted systems [4], [11]. We suitably extend CTL cc to deal with other actions, such as cancel, and delegate to flexibly capture more business scenarios.…”