1,720,964 research outputs found
Behavioural Properties and Dynamic Software Update for Concurrent Programs, Thesis Progress Report
No full textCorrectly developing multi-threaded programs is notoriously difficult, and getting total coverage using traditional testing paradigms, to guarantee the program is correct, is often infeasible. We expand on previous work to provide various tools, namely a generalisation of session typing and an extension of policy automata to multi-threaded code, with which to verify multi-threaded code. Additionally, most programs are not written once and then left; maintaining and updating software is an essential part of the software development cycle. Dynamic software update (DSU) “is a technique by which a running program can be updated with new code and data without interrupting its execution” [45] and uses code analyses to ensure given safety properties are maintained across update boundaries. We present techniques for verifying if a modification can be applied to a running program whilst maintaining the desired behavioural properties, which may be those the program had before or some new properties
Type and Effect Systems for Dynamically Changing Code - DRAFT CORRECTIONS, DO NOT DISTRIBUTE
No full textWe extend type and effect analyses to permit dynamically changing effects and dynamically changing code in multi-threaded systems with shared resources. We guarantee that after a well typed modification a set of threads will have the specified desired effects and will continue to safely use the resources. We prove the key properties of subject reduction and fidelity (safety) for our general system. We provide an application of our system: dynamic software updating for a multi-threaded asynchronous message passing system. We show how key safety properties from session typing follow from the properties of our general system
Behavioural properties and dynamic software update for concurrent programmes
No full textSoftware maintenance is a major part of the development cycle. The traditional methodology for rolling out an update to existing programs is to shut down the system, modify the binary, and restart the program. Downtime has significant disadvantages. In response to such concerns, researchers and practitioners have investigated how to perform update on running programs whilst maintaining various desired properties. In a multi-threaded setting this is further complicated by the interleaving of different threads' actions. In this thesis we investigate how to prove that safety and liveness are preserved when updating a program. We present two possible approaches; the main intuition behind each of these is to find quiescent points where updates are safe. The first approach requires global synchronisation, and is more generally applicable, but can delay updates indefinitely. The second restricts the class of programs that can be updated, but permits update without global synchronisation, and guarantees application of update. We provide full proofs of all relevant properties
Migrating Protocols In Multi-Threaded Message-Passing Systems
Full text linkDynamic software update is a technique by which a running program can be updated with new code and data without interrupting its execution. Often we will want to preserve properties of programs across update boundaries. Preserving simple typing across update boundaries for single-threaded programs is well studied. There are other higher-level properties we may wish to preserve, particularly for multi-threaded programs. Session typing is used to guarantee that a set of parallel threads communicate according to a given protocol. Hence we investigate preserving correct communications behaviour of a set of parallel threads correctly across update boundaries which change the running protocol. We present a procedure for updating multiple threads to cleanly migrate a system from one protocol to another
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
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
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