A History of Until

Until is a notoriously difficult temporal operator as it is both existential and universal at the same time: A until B holds at the current time instant w iff either B holds at w or there exists a time instant w' in the future at which B holds and such that A holds in all the time instants between the current one and w'. This "ambivalent" nature poses a significant challenge when attempting to give deduction rules for until. In this paper, in contrast, we make explicit this duality of until to provide well-behaved natural deduction rules for linear-time logics by introducing a new temporal operator that allows us to formalize the "history" of until, i.e., the "internal" universal quantification over the time instants between the current one and w'. This approach provides the basis for formalizing deduction systems for temporal logics endowed with the until operator. For concreteness, we give here a labeled natural deduction system for a linear-time logic endowed with the new operator and show that, via a proper translation, such a system is also sound and complete with respect to the linear temporal logic LTL with until.Comment: 24 pages, full version of paper at Methods for Modalities 2009 (M4M-6

Pose and Shape Reconstruction of a Noncooperative Spacecraft Using Camera and Range Measurements

Recent interest in on-orbit proximity operations has pushed towards the development of autonomous GNC strategies. In this sense, optical navigation enables a wide variety of possibilities as it can provide information not only about the kinematic state but also about the shape of the observed object. Various mission architectures have been either tested in space or studied on Earth. The present study deals with on-orbit relative pose and shape estimation with the use of a monocular camera and a distance sensor. The goal is to develop a filter which estimates an observed satellite's relative position, velocity, attitude, and angular velocity, along with its shape, with the measurements obtained by a camera and a distance sensor mounted on board a chaser which is on a relative trajectory around the target. The filter's efficiency is proved with a simulation on a virtual target object. The results of the simulation, even though relevant to a simplified scenario, show that the estimation process is successful and can be considered a promising strategy for a correct and safe docking maneuver

Vertical Specialisation and Regional Trade Integration. A Study on Italy and Northern African Countries

This paper uses a multistage approach to investigate the role of Italy in the Northern African countries, both in terms of trade and investment. In particular, we show that Italian import flows for two typically Made in Italy industries, namely textile and clothing on one hand, and leather and footwear on the other hand, are strongly related not only to export flows of the same sector, but also to a set of variables capturing features of the Italian and the foreign country. In this way, we supply a first result supporting the hypothesis of an international fragmentation of production. To offer this outcome additional strength, we endow the present contribution with information on the attractiveness of the Northern African countries, looking at the volume of inward FDI flows and stocks, but with no industry disaggregation, due to data unavailability. Although we start from a global perspective, we rapidly shift to consider only the Italian investments in the area, with a breakdown by outward region. Thanks to the availability of a detailed dataset made available by the Bank of Italy, we are able to provide further evidence on the Italian internationalisation in the North of Africa. Indeed, our second result highlights the remarkable heterogeneity across countries and the emergence of the major role played by Tunisia.Northern Africa, Italian regions, Made in Italy, FDI, fragmentation, Global Value Chains

International ENGOs in China: a Significant Presence and a Fast-Changing Reality

本文通过回顾非政府组织的发展历程及其在国 际政治中的作用，考察国际环境非政府组织对中国 环境治理的影响，以及中国境外非政府组织境内活 动管理法《中华人民共和国境外非政府组织境内活 动管理法》的主要含义。通过对国际气候变化会 议中中国领导层行为历时变化的分析，探讨了中国 国际环境非政府组织的现状、决策和项目。本文认 为，国际环境非政府组织对保护中国环境、形成公 民社会以及加强环境保护意识和公众参与意识起到 了积极作用。《中华人民共和国境外非政府组织境 内活动管理法》的实现对国际环境非政府组织起到 了更为严格的监督作用，其效果有待进一步研究。 The paper examines the impact that international ENGOs have had on Chinese environment situation and the implication of the Law of People’s Republic of China on the Administration of the Activities of Overseas Nongovernmental Organisations in Mainland China. Based on the review of historical profile of NGOs and their enhanced role within the international politics, the paper analyzes China’s leadership evolutionary behaviour in international climate change conferences and investigates the international ENGOs’ current status, strategies and projects in China. The paper argues that international ENGOs have had a positive, even if limited, impact in protecting Chinese environment and in supporting Chinese civil society to emerge and strengthening the public participation and awareness. It also argues that, the implementation of the new law certainly puts international NGOs under higher scrutiny; however, further implications are, to date, only partially predictable

An interpolation-based method for the verification of security protocols

Interpolation has been successfully applied in formal methods for model checking and test-case generation for sequential programs. Security protocols, however, exhibit such idiosyncrasies that make them unsuitable to the direct application of interpolation. We address this problem and present an interpolation-based method for security protocol verification. Our method starts from a protocol specification and combines Craig interpolation, symbolic execution and the standard Dolev-Yao intruder model to search for possible attacks on the protocol. Interpolants are generated as a response to search failure in order to prune possible useless traces and speed up the exploration. We illustrate our method by means of concrete examples and discuss the results obtained by using a prototype implementation

Certification of Prefixed Tableau Proofs for Modal Logic

International audienceDifferent theorem provers tend to produce proof objects in different formats and this is especially the case for modal logics, where several deductive formalisms (and provers based on them) have been presented. This work falls within the general project of establishing a common specification language in order to certify proofs given in a wide range of deductive formalisms. In particular, by using a translation from the modal language into a first-order polarized language and a checker whose small kernel is based on a classical focused sequent calculus, we are able to certify modal proofs given in labeled sequent calculi, prefixed tableaux and free-variable prefixed tableaux. We describe the general method for the logic K, present its implementation in a Prolog-like language, provide some examples and discuss how to extend the approach to other normal modal logics

Whitney stratifications are conically smooth

In their paper "Local structures on stratified spaces", Ayala, Francis and Tanaka introduced the notion of conically smooth structure on stratified spaces. This is a very well behaved analogous of a differential structure in the context of manifold stratified topological spaces, satisfying good properties such as the existence of resolutions of singularities and handlebody decompositions. In this paper we prove that any Whitney stratified space admits a conically smooth structure, as conjectured by Ayala, Francis and Tanaka themselves, thus establishing a connection between this new theory and the classical examples of stratified spaces from differential topology.Comment: 15 page