Verification of Agent-Based Artifact Systems

Abstract

Artifact systems are a novel paradigm for specifying and implementing business processes described in terms of interacting modules called artifacts. Artifacts consist of data and lifecycles, accounting respectively for the relational structure of the artifacts' states and their possible evolutions over time. In this paper we put forward artifact-centric multi-agent systems, a novel formalisation of artifact systems in the context of multi-agent systems operating on them. Differently from the usual process-based models of services, we give a semantics that explicitly accounts for the data structures on which artifact systems are defined.We study the model checking problem for artifact-centric multi-agent systems against specifications expressed in a quantified version of temporal-epistemic logic expressing the knowledge of the agents in the exchange. We begin by noting that the problem is undecidable in general. We identify a noteworthy class of systems that admit bisimilar, finite abstractions. It follows that we can verify these systems by investigating their finite abstractions; we also show that the corresponding model checking problem is EXPSPACE-complete. We then introduce artifact-centric programs, compact and declarative representations of the programs governing both the artifact system and the agents. We show that, while these in principle generate infinite-state systems, under natural conditions their verification problem can be solved on finite abstractions that can be effectively computed from the programs. We exemplify the theoretical results here pursued through a mainstream procurement scenario from the artifact systems literature.

Linking Data and BPMN Processes to Achieve Executable Models

“…In terms of the framework for modeling data and business processes, many of the existing works [9][10][11] use languages grounded on logic, which are formal and unambiguous but more difficult to understand than BPMN and UML. There are other approaches which use graphical representations which are more intuitive and appealing to business analysts and developers, such as [12,22,23].…”

“…Recent research is bringing forward the necessity of considering both data and processes as first-class citizens in process and service design [7][8][9]. In particular, the so called artifact-centric approaches, which advocate a sort of middle ground between a conceptual formalization of dynamic systems and their actual implementation, are promising to be quite effective in practice [6,10,11].…”

Progression and Verification of Situation Calculus Agents with Bounded Beliefs

“…As a result a basic action theory D is the union of the following disjoint sets: the foundational, domain independent, (second-order, or SO) axioms of the situation calculus (Σ); (first-order, or FO) action precondition axioms stating when actions can be legally performed and characterizing Poss (D ap ); (FO) successor state axioms describing how fluents change between situations (D ss ); (FO) unique name axioms for actions and (FO) domain closure axioms on action types (D una ); (SO) unique name and domain closure axioms for object constants (D coa ); and (FO) axioms describing the initial configuration of the world (D 0 ), which we assume finite. 4 Note that successor state axioms encode the causal laws of the domain; they take the place of the so-called effect axioms and provide a solution to the frame problem.…”

“…Interestingly, while we have verification tools that are quite good for dealing with data and processes separately, when we consider them together, we get infinite-state transition systems, which resist classical model checking approaches to verification. Lately, there has been some work on developing verification techniques that can deal with such infinite-state processes [1,2,4,19]. In particular [2,4] brings forth the idea of exploiting state boundedness to get decidability for verification of infinite-state dataaware systems.…”

Verification of GSM-Based Artifact-Centric Systems by Predicate Abstraction

“…Several techniques for the verification of artifact-centric systems have been put forward [8][9][10][11][12][13]. While these provide considerable insight in the decidability and complexity of the verification problem, they do not provide a concrete verification technique for actual systems.…”