1,721,021 research outputs found
Aperiodicity, Star-freeness, and First-order Logic Definability of Operator Precedence Languages
Full text linkA classic result in formal language theory is the equivalence among
non-counting, or aperiodic, regular languages, and languages defined through
star-free regular expressions, or first-order logic. Past attempts to extend
this result beyond the realm of regular languages have met with difficulties:
for instance it is known that star-free tree languages may violate the
non-counting property and there are aperiodic tree languages that cannot be
defined through first-order logic. We extend such classic equivalence results
to a significant family of deterministic context-free languages, the
operator-precedence languages (OPL), which strictly includes the widely
investigated visibly pushdown, alias input-driven, family and other structured
context-free languages. The OP model originated in the '60s for defining
programming languages and is still used by high performance compilers; its rich
algebraic properties have been investigated initially in connection with
grammar learning and recently completed with further closure properties and
with monadic second order logic definition. We introduce an extension of
regular expressions, the OP-expressions (OPE) which define the OPLs and, under
the star-free hypothesis, define first-order definable and non-counting OPLs.
Then, we prove, through a fairly articulated grammar transformation, that
aperiodic OPLs are first-order definable. Thus, the classic equivalence of
star-freeness, aperiodicity, and first-order definability is established for
the large and powerful class of OPLs. We argue that the same approach can be
exploited to obtain analogous results for visibly pushdown languages too
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
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
Weighted Operator Precedence Languages
Full text linkIn the last years renewed investigation of operator precedence languages (OPL) led to discover important properties thereof: OPL are closed with respect to all major operations, are characterized, besides the original grammar family, in terms of an automata family (OPA) and an MSO logic; furthermore they significantly generalize the well-known visibly pushdown languages (VPL). In another area of research, quantitative models of systems are also greatly in demand. In this paper, we lay the foundation to marry these two research fields. We introduce weighted operator precedence automata and show how they are both strict extensions of OPA and weighted visibly pushdown automata. We prove a Nivat-like result which shows that quantitative OPL can be described by unweighted OPA and very particular weighted OPA. In a Büchi-like theorem, we show that weighted OPA are expressively equivalent to a weighted MSO-logic for OPL
sMALL CaPS: An Infinitary Linear Logic for a Calculus of Pure Sessions
No full textWe present an infinitary version of Multiplicative Additive Linear Logic (sMALL) that serves as logical foundation for a Calculus of Pure Sessions (CaPS). sMALL is infinitary not only because proof derivations may be infinite, but also because propositions themselves may be infinite. In this sense, sMALL differs from other related extensions of Linear Logic based on least and greatest fixed points. Also, all sMALL derivations are valid proofs by construction. sMALL enables the description and implementation in CaPS of recursive communication protocols – like authentication, coordination, consensus – in which termination is not decided autonomously by a single process, but results from some negotiation involving two or more interacting processes. We prove that sMALL is sound and that it enjoys cut elimination. We also prove a relative completeness result showing that a certain class of well-behaving CaPS processes are well typed in sMALL. Finally, we show that sMALL can be easily extended to address a broader class of fairly terminating processes, those that terminate under a suitable fairness assumption
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