We study syntax-free models for name-passing processes. For interleaving semantics, we identify the indexing structure required of an early labelled transition system to support the usual pi-calculus operations, defining Indexed Labelled Transition Systems. For noninterleaving causal semantics we define Indexed Labelled Asynchronous Transition Systems, smoothly generalizing both our interleaving model and the standard Asynchronous Transition Systems model for CCS-like calculi. In each case we relate a denotational semantics to an operational view, for bisimulation and causal bisimulation respectively. We establish completeness properties of, and adjunctions between, categories of the two models. Alternative indexing structures and possible applications are also discussed. These are first steps towards a uniform understanding of the semantics and operations of name-passing calculi.

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Regulatory compliance of business operations is a critical problem for enterprises. As enterprises increasingly use business process management systems to automate their business processes, technologies to automatically check the compliance of process models against compliance rules are becoming important. In this paper, we present a method to improve the reliability and minimize the risk of failure of business process management systems from a compliance perspective. The proposed method allows separate modeling of both process models and compliance concerns. Business process models expressed in the Business Process Execution Language are transformed into pi-calculus and then into finite state machines. Compliance rules captured in the graphical Business Property Specification Language are translated into linear temporal logic. Thus, process models can be verified against these compliance rules by means of model-checking technology. The benefit of our method is threefold: Through the automated verification of a large set of business process models, our approach increases deployment efficiency and lowers the risk of installing noncompliant processes; it reduces the cost associated with inspecting business process models for compliance; and compliance checking may ensure compliance of new process models before their execution and thereby increase the reliability of business operations in general.

Abstract. This paper describes the architecture of a toolkit, called Mihda, providing facilities to minimise labelled transition systems for name passing calculi. The structure of the toolkit is derived from the co-algebraic formulation of the partition-refinement minimisation algorithm for HD-automata. HD-automata have been specifically designed to allocate and garbage collect names and they provide faithful finite state representations of the behaviours of π-calculus processes. The direct correspondence between the coalgebraic specification and the implementation structure facilitates the proof of correctness of the implementation. We evaluate the usefulness of Mihda in practise by performing finite state verification of π-calculus specifications. 1

We propose a technique for the analysis of infinite-state graph transformation systems, based on the construction of finite structures approximating their behaviour. Following a classical approach, one can construct a chain of finite underapproximations (k-truncations) of the Winskel style unfolding of a graph grammar. More interestingly, also a chain of finite over-approximations (k-coverings) of the unfolding can be constructed. The fact that k-truncations and k-coverings approximate the unfolding with arbitrary accuracy is formalised by showing that both chains converge (in a categorical sense) to the full unfolding. We discuss how the finite over- and under-approximations can be used to check properties of systems modelled by graph transformation systems, illustrating this with some small examples. We also describe the Augur tool, which provides a partial implementation of the proposed constructions, and has been used for the verification of larger case studies.

... syntax and functorial operational semantics to give a compositional and fully abstract semantics for the π-calculus equipped with open bisimulation. The key novelty in our work is the realisation that the sophistication of open bisimulation requires us to move from the usual semantic domain of presheaves over subcategories of Set to presheaves over subcategories of Rel. This extra structure is crucial in controlling the renaming of extruded names and in providing a variety of different dynamic allocation operators to model the different binders of the π-calculus.

Abstract. Nominal calculi have been shown very effective to formally model a variety of computational phenomena. The models of nominal calculi have often infinite states, thus making model checking a difficult task. In this note we survey some of the approaches for model checking nominal calculi. Then, we focus on History-Dependent automata, a syntax-free automaton-based model of mobility. History-Dependent automata have provided the formal basis to design and implement some existing verification toolkits. We then introduce a novel syntax-free setting to model the symbolic semantics of a nominal calculus. Our approach relies on the notions of reactive systems and observed borrowed contexts introduced by Leifer and Milner, and further developed by Sassone, Lack and Sobocinski. We argue that the symbolic semantics model based on borrowed contexts can be conveniently applied to web service discovery and binding. 1

We introduce finite-state verification techniques for the π-calculus whose design and correctness are justified coalgebraically. In particular, we formally specify and implement a minimisation algorithm for HD-automata derived from π-calculus agents. The algorithm is a generalisation of the partition refinement algorithm for classical automata and is specified as a coalgebraic construction defined using λ →,Π,Σ, a polymorphic λ-calculus with dependent types. The convergence of the algorithm is proved; moreover, the correspondence of the specification and the implementation is shown. 1

this paper. It shoud be pointed out that in order to concentrate on the security of the protocol and not on the security of the cryptographic algorithm used, in the vast of formal method approaches it is assumed true the the following perfect encryption assumption [14]: Definition 1 (Perfect Encryption Assumption). The decryption key K must be known to extract the plaintext T from a cyphertext fTgK encrypted with K. Moreover, there is enough redundancy in the system that a cyphertext can be generated only using the appropriate encryption key. This also implies that if there are two identical cyphertexts fT 1 gK1 = fT 2 gK2 then they must have been generated from the same plaintext using the same key, that is T 1 = T 2 and K 1 = K 2