A lightweight BPMN extension for business process-oriented requirements engineering

Process-oriented requirements engineering approaches are often required to deal with the effective adaptation of existing processes in order to easily introduce new or updated requirements. Such approaches are based on the adoption of widely used notations, such as the one introduced by the Business Process Model and Notation (BPMN) standard. However, BPMN models do not convey enough information on the involved entities and how they interact with process activities, thus leading to ambiguities, as well as to incomplete and inconsistent requirements definitions. This paper proposes an approach that allows stakeholders and software analysts to easily merge and integrate behavioral and data properties in a BPMN model, so as to fully exploit the potential of BPMN without incurring into the aforementioned limitation. The proposed approach introduces a lightweight BPMN extension that specifically addresses the annotation of data properties in terms of constraints, i.e., pre- and post-conditions that the different process activities must satisfy. The visual representation of the annotated model conveys all the information required both by stakeholders, to understand and validate requirements, and by software analysts and developers, to easily map these updates to the corresponding software implementation. The presented approach is illustrated by use of two running examples, which have also been used to carry out a preliminary validation activity

Application-Layer Connector Synthesis

International audienceThe heterogeneity characterizing the systems populating the Ubiquitous Computing environment prevents their seamless interoperability. Heterogeneous protocols may be willing to cooperate in order to reach some common goal even though they meet dynamically and do not have a priori knowledge of each other. Despite numerous e orts have been done in the literature, the automated and run-time interoperability is still an open challenge for such environment. We consider interoperability as the ability for two Networked Systems (NSs) to communicate and correctly coordinate to achieve their goal(s). In this chapter we report the main outcomes of our past and recent research on automatically achieving protocol interoperability via connector synthesis. We consider application-layer connectors by referring to two conceptually distinct notions of connector: coordinator and mediator. The former is used when the NSs to be connected are already able to communicate but they need to be speci cally coordinated in order to reach their goal(s). The latter goes a step forward representing a solution for both achieving correct coordination and enabling communication between highly heterogeneous NSs. In the past, most of the works in the literature described e orts to the automatic synthesis of coordinators while, in recent years the focus moved also to the automatic synthesis of mediators. Within the Connect project, by considering our past experience on automatic coordinator synthesis as a baseline, we propose a formal theory of mediators and a related method for automatically eliciting a way for the protocols to interoperate. The solution we propose is the automated synthesis of emerging mediating connectors (i.e., mediators for short)

Church-Rosser lambda-theories, infinite lambda-terms and consistency problems

We treat a general technique to obtain Church - Rosser extensions of the lambda-beta-calculus, based on the notion of ``confining class'' and on an infinitary version of lambda-calculus. We apply the technique to find a large class of terms which can be consistently equated to every other term, and we also show that many equations between lambda-terms can be consistently added to the the lambda-beta-calculus

Combinatorial principles in elementary number theory

We prove that the theory IΔ0, extended by a weak version of the Δ0-Pigeonhole Principle, proves that every integer is the sum of four squares (Lagrange's theorem). Since the required weak version is derivable from the theory IΔ0 + ∀x (xlog(x) exists), our results give a positive answer to a question of Macintyre (1986). In the rest of the paper we consider the number-theoretical consequences of a new combinatorial principle, the ‘Δ0-Equipartition Principle’ (Δ0EQ). In particular we give a new proof, which can be formalized in IΔ0 + Δ0EQ, of the fact that every prime of the form 4n + 1 is the sum of two squares

On the cop number of a graph

The cop number c(G) of a graph G is an invariant connected with the genus and the girth. We prove that for a fixed k there is a polynomial-time algorithm which decides whether c(G) ≤ k. This settles a question of T. Andreae. Moreover, we show that every graph is topologically equivalent to a graph with c ≤ 2. Finally we consider a pursuit-evasion problem in Littlewood′s miscellany. We prove that two lions are not always sufficient to catch a man on a plane graph, provided the lions and the man have equal maximum speed. We deal both with a discrete motion (from vertex to vertex) and with a continuous motion. The discrete case is solved by showing that there are plane graphs of cop number 3 such that all the edges can be represented by straight segments of the same length

The commutative equivalence of bounded context-free and regular languages

It is proved that every bounded context-free language L is commutatively equivalent to a regular language L', that is, there exists a bijection from L onto L' preserving the Parikh vectors of words

On the commutative equivalence of bounded context-free and regular languages: The code case

This is the first paper of a group of three where we prove the following result. Let A be an alphabet of t letters and let psi : A* -> N-t be the corresponding Parikh morphism. Given two languages L-1, L-2 subset of A*, we say that L1 is commutatively equivalent to L-2 if there exists a bijection f : L-1 -> L-2 from L-1 onto L-2 such that, for every u is an element of L-1, psi (u) = psi (f (u). Then every bounded context-free language is commutatively equivalent to a regular language. (C) 2014 Elsevier B.V. All rights reserved

On the generalization of Higman and Kruskal's theorems to regular languages and rational trees

In this paper we give new extensions and generalizations of the Higman and Kruskal theorems. We start with an alphabet A equipped by a well quasi-order (wqo) less than or equal to and prove that a natural extension of this order to the family of regular languages over A is a wqo. A similar extension is given for rational trees with labels in A, proving that also in this case one obtains a wqo. We prove that the above wqo's are effectively computable, that is, for any two regular languages (rational trees) one can decide whether they are comparable in the given wqo