1,720,995 research outputs found
Logics for Extensional, Locally Complete Analysis via Domain Refinements
Full text linkAbstract interpretation is a framework to design sound static analyses by over-approximating the set of program behaviours. While over-approximations can prove correctness, they cannot witness incorrectness because false alarms may arise. An ideal, but uncommon, situation is completeness of the abstraction that can ensure no false alarm is introduced by the abstract interpreter. Local Completeness Logic is a proof system that can decide both correctness and incorrectness of a program: any provable triple ⊢A [P] c [Q] in the logic implies completeness of an intensional abstraction of program c on input P and is such that Q can be used to decide (in)correctness. However, completeness itself is an extensional property of the function computed by the program, while the above intensional analysis depends on the way the program is written and therefore not all valid triples can be derived in the proof system. Our main contribution is the study of new inference rules which allow one to perform part of the intensional analysis in a more precise abstract domain, and then to transfer the result back to the coarser domain. With these new rules, all (extensionally) valid triples can be derived in the proof system, thus untying the set of provable properties from the way the program is written
Revealing Sources of (Memory) Errors via Backward Analysis
No full textSound over-approximation methods are effective for proving the absence of errors, but inevitably produce false alarms that can hamper programmers. In contrast, under-approximation methods focus on bug detection and are free from false alarms. In this work, we present two novel proof systems designed to locate the source of errors via backward under-approximation, namely Sufficient Incorrectness Logic (SIL) and its specialization for handling memory errors, called Separation SIL. The SIL proof system is minimal, sound and complete for Lisbon triples, enabling a detailed comparison of triple-based program logics across various dimensions, including negation, approximation, execution order, and analysis objectives. More importantly, SIL lays the foundation for our main technical contribution, by distilling the inference rules of Separation SIL, a sound and (relatively) complete proof system for automated backward reasoning in programs involving pointers and dynamic memory allocation. The completeness result for Separation SIL relies on a careful crafting of both the assertion language and the rules for atomic commands
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
Limits and difficulties in the design of under-approximation abstract domains
No full textStatic analyses are mostly designed to show the absence of bugs: if the analysis reports no alarms then the program won’t exhibit any unwanted behaviours. To this aim they manipulate over-approximations of program semantics and, inevitably, they often report some false alarms. Recently, O’Hearn proposed Incorrectness Logic, that is based on under-approximations, as a formal method to find bugs that only reports true alarms. In this paper we aim to answer one important question raised by O’Hearn, namely which role can Abstract Interpretation play for the development of under-approximate tools for bug catching. In principle, Abstract Interpretation based static analyses can be defined for computing over-approximations as well as under-approximations, but in practice, most techniques exploited the former while few attempts developed the latter. To show why it is difficult to design effective under-approximation abstract domains, we first propose the new definitions of non emptying functions and highly surjective function family and then we formally prove the limits of under-approximation analysis by showing the non existence of abstract domains able to approximate such functions in a non trivial way. Our results outline the limits of under-approximation Abstract Interpretation and clarify, for the first time, why over- and under- approximation analyzers exhibited such a different development
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
