1,721,070 research outputs found
On topologies for (hyper)properties
Full text linkUsually, systems properties are defined in terms of the infinite executions which satisfy it. In this work we explore what happens if we allow finite executions in properties de-nitions. In particular, we give a topological interpretation of the safety/liveness classification in the do-mains of: only finite, only infinite and mixed executions. Then we extend our reasoning to hyperproperties, namely sets of sets of executions (or sets of properties). Also in this case we give a topological interpretation of the hypersafety/hyperliveness classification in the three domains
On the Security and Safety of AbU Systems
No full textAttribute-based memory updates (AbU in short) is an interaction mechanism recently introduced for adapting the Event-Condition-Action (ECA) programming paradigm to distributed systems, particularly suited for the IoT. It can be seen as a memory-based counterpart of attribute-based communication, keeping the simplicity of ECA rules. In this paper, we introduce behavioral equivalences for AbU, with the aim of formally defining security and safety requirements for AbU systems. As a consequence, the proposed requirements can help in assuring the security and safety of IoT devices, which are more and more pervasive in our daily life. Finally, we propose (syntactic) sufficient conditions to statically verify the introduced requirements
Rationalization and Design of Enhanced Photoinduced Cycloreversion in Photochromic Dimethyldihydropyrenes by Theoretical Calculations
No full textThis study presents a computational investigation of the initial step of the dimethyldihydropyrene (DHP) to cyclophanediene (CPD) photoinduced ring-opening reaction using time-dependent density functional theory (TD-DFT). In particular, the photochemical path corresponding to the formation of the CPD precursor (CPD*) on the zwitterionic state is scrutinized. The TD-DFT approach was first validated on the parent compound against accurate ab initio calculations. It confirms that CPD* formation is efficiently quenched in this system by an easily accessible S2/S1 conical intersection located in the vicinity of the CPD* minimum and leading to a locally excited state minimum responsible for DHP luminescence. Increased ring-opening quantum yields were observed in benzo[e]-fused-DHP (DHP-1), isobutenyl-DHP (DHP-2), and naphthoyl-DHP (DHP-3). The calculations show that CPD* formation is much more favorable in these systems, either due to an inversion of electronic states in DHP-1, suppressing the formation of the locally excited state, or due to efficient stabilization of CPD* on the S1 potential energy surface in DHP-2 and DHP-3. Both effects can be combined in a rationally designed benzo[e]-fused-naphthoyl-DHP (DHP-4) for which we anticipate an unprecedented efficiency
Distributed Programming of Smart Systems with Event-Condition-Action Rules
Full text linkIn recent years, event-driven programming languages, e.g. those based on Event Condition Action (ECA) rules, have emerged as a promising paradigm for implementing smart systems, such as IoT devices. Still, actual implementations are bound to a centralized infrastructure, limiting scalability and security. In this work, we present attribute-based memory updates (AbU), a new interaction mechanism aiming to extend the ECA programming paradigm to distributed systems. It relies on attribute-based communication, that is similar to broadcast, but receivers are selected “on the fly” by means of predicates over their attributes. With AbU, smart devices can be easily programmed via ECA rules and, at the same time, they can be deployed to a distributed network. Hence, a centralized infrastructure is not needed anymore: the computation is moved on the edge, improving reliability, scalability, privacy and security
An abstract domain for objects in dynamic programming languages
Full text linkDynamic languages, such as JavaScript, PHP, Python or Ruby, provide a memory model for objects data structures allowing programmers to dynamically create, manipulate, and delete objects’ properties. Moreover, in dynamic languages it is possible to access and update properties by using strings: this represents a hard challenge for static analysis. In this paper, we exploit the finite state automata abstract domain, approximating strings, in order to define a novel abstract domain for objects. We design an abstract interpreter useful to analyze objects in a toy language, inspired by real-word dynamic programming languages. We then show, by means of minimal yet expressive examples, the precision of the proposed abstract domain
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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