1,721,003 research outputs found
Constraint contextual rewriting
No full textAbstractThe effective integration of decision procedures in formula simplification is a fundamental problem in mechanical verification. In this paper we address the problem by proposing a general pattern of interaction between rewriting and decision procedures and by providing an account of such a pattern of interaction which is precise and concise at the same time. The first step amounts to a generalization of contextual rewriting which allows the available decision procedure to access and manipulate the rewriting context. We call this generalized form of contextual rewriting constraint contextual rewriting (CCR for short). The second step amounts to providing a rule-based presentation of CCR which is modular, declarative, and formal at the same time. This allows us to give a rigorous account of CCR and to formally state and prove its soundness and termination
A Practical Extension Mechanism for Decision Procedures: the Case Study of Universal Presburger Arithmetic
No full textIn this paper, we propose a generic mechanism for extending decision procedures by means of a lemma speculation mechanism. This problem is important in order to widen the scope of decision procedures incorporated in state-of-the-art verification systems. Soundness and termination of the extension schema are formally stated and proved. As a case study, we consider extensions of a decision procedure for the quantifier-free fragment of Presburger Arithmetic to significant fragments of non-linear arithmetic
Formal Modelling of Content-Based Protection and Release for Access Control in NATO Operations
No full textThe successful operation of NATO missions requires the effective and secure sharing of information among coalition partners and external organizations, while avoiding the disclosure of sensitive information to unauthorized users. To resolve the conflict between confidentiality and availability in a dynamic coalition and network environment while being able to dynamically respond to changes in protection requirements and release conditions, NATO is developing a new information sharing infrastructure. In this paper we present the Content-based Protection and Release (CPR) access control model for the NATO information sharing infrastructure. We define a declarative specification language for CPR based on the first-order logical framework underlying a class of efficient theorem-proving tools, called Satisfiability Modulo Theories solvers, and describe how they can support answering authorization queries. We illustrate the ideas in a use case scenario drawn from the NATO Passive Missile Defence system for simulating the consequences of intercepting missile attacks
Do Security Reports Meet Usability?: Lessons Learned from Using Actionable Mitigations for Patching TLS Misconfigurations
No full textSeveral automated tools have been proposed to detect vulnerabilities. These tools are mainly evaluated in terms of their accuracy in detecting vulnerabilities, but the evaluation of their usability is a commonly neglected topic. Usability of automated security tools is particularly crucial when dealing with problems of cryptographic protocols for which even small - apparently insignificant - changes in their configuration can result in vulnerabilities that, if exploited, pave the way to attacks with dramatic consequences for the confidentiality and integrity of exchanged messages. This becomes even more acute when considering such ubiquitous protocols as the one for Transport Layer Security (TLS for short). In this paper, we present the design and the lessons learned of a user study, meant to compare two different approaches when reporting misconfigurations. Results reveal that including contextualized actionable mitigations in security reports significantly impact the accuracy and the time needed to patch TLS vulnerabilities. Along with the lessons learned, we share the experimental material that can be used during cybersecurity labs to let students configure and patch TLS first-hand
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
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