1,720,962 research outputs found
C-tableaux
Full text linkThe Nelson-Oppen combination method combines decision procedures for first-order theories satisfying certain conditions into a single decision procedure for the union theory. The method is restricted to the combination of stably infinite theories over disjoint signatures. In this report we present C-tableaux, an extension of Smullyan tableaux that generalizes the Nelson-Oppen method to the combination of arbitrary universal theories, not necessarily stably infinite and not necessarily over disjoint signatures. C-tableaux are sound and complete, but not terminating in general. Although C-tableaux do not provide a decidability result in general, in this report we describe two approaches that can be used in order to obtain decidability results using C-tableaux. Using the first approach, we are able to obtain a decidability result when combining theories that share the dense orders. Using the second approach, we are able to obtain a decidability result when combining theories whose union is stably finite
C-tableaux
No full textThe Nelson-Oppen combination method combines decision procedures for first-order theories satisfying certain conditions into a single decision procedure for the union theory. The method is restricted to the combination of stably infinite theories over disjoint signatures. In this report we present C-tableaux, an extension of Smullyan tableaux that generalizes the Nelson-Oppen method to the combination of arbitrary universal theories, not necessarily stably infinite and not necessarily over disjoint signatures. C-tableaux are sound and complete, but not terminating in general. Although C-tableaux do not provide a decidability result in general, in this report we describe two approaches that can be used in order to obtain decidability results using C-tableaux. Using the first approach, we are able to obtain a decidability result when combining theories that share the dense orders. Using the second approach, we are able to obtain a decidability result when combining theories whose union is stably finite
Combining Non-Stably Infinite Theories
No full textAbstractThe Nelson-Oppen combination method combines decision procedures for first-order theories over disjoint signatures into a single decision procedure for the union theory. To be correct, the method requires that the component theories be stably infinite. This restriction makes the method inapplicable to many interesting theories such as, for instance, theories having only finite models.In this paper we provide a new combination method that can combine any theory that is not stably infinite with another theory, provided that the latter is what we call a shiny theory. Examples of shiny theories include the theory of equality, the theory of partial orders, and the theory of total orders.An interesting consequence of our results is that any decision procedure for the satisfiability of quantifier-free Σ-formulae in a Σ-theory T can always be extended to accept inputs over an arbitrary signature Ω ⊇ Σ
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
Combining Data Structures with Nonstably Infinite Theories using Many-Sorted Logic
No full textMost computer programs store elements of a given nature into container-based data structures such as lists, arrays, sets, and multisets. To verify the correctness of these programs, one needs to combine a theory modeling the data structure with a theory modeling the elements. This combination can be achieved using the classic Nelson-Oppen method only if both theories are stably infinite. The goal of this report is to relax the stable infiniteness requirement. To achieve this goal, we introduce the notion of polite theories, and we show that natural examples of polite theories include those modeling data structures such as lists, arrays, sets, and multisets. Furthemore, we provide a method that is able to combine a polite theory with any theory of the elements, regardless of whether the latter is stably infinite or not. The results of this report generalize to many-sorted logic those recently obtained by Tinelli and Zarba for combining the so-called shiny theories with nonstably infinite theories in one-sorted logic
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