1,721,344 research outputs found
An intuitionistic theory of types with assumptions of high-arity variables
No full textAfter an introductory discussion on Martin-Löf's Intuitionistic Theory of Types (ITT), the paper introduces the notion of assumption of high-arity variable. Then the original theory is extended (HITT) in a very uniform way by means of the new assumptions. Some improvements allowed by high-arity variables are shown. The main result of the paper is a normal form theorem for HITT. The detailed proof follows a computability method ‘a la Tait’. The main consequences of the normal form theorem are: the consistency of HITT, which also implies the consistency of ITT, and the computability of any judgement derived within HITT. Besides that, a canonical form theorem is shown: to any derivable judgement we can associate a canonical one whose derivation ends with an introductory rule. The standard disjunction and existential properties follow. Moreover, by using the computational interpretation of types it immediately follows that the execution of any proved correct program terminates
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
Implications of prostate-specific antigen doubling time as indicator of failure after surgery or radiation therapy for prostate cancer
No full textObjectives: To review the methodology of PSA doubling time (PSA DT) calculations and the implications of PSA DT for the follow-up of prostate cancer patients curatively treated with surgery or radiation therapy. Methods: A literature search of the most recent articles on PSA DT (those published after 2000) led to the selection of six studies with the largest and best-documented cohorts of patients treated with surgery or irradiation with curative intent. Results: PSA kinetics, in the form of PSA DT, is the most effective parameter for identifying patients at significant risk for mortality specific to prostate cancer. Thresholds of 3, 6, and 12 mo have shown prognostic significance both in surgical and radiation series, notwithstanding differences in treatment selection, definition of biochemical recurrence, and methods of DT calculation. Conclusions: In retrospective studies, PSA DT is a reliable predictor of prognosis; however, prospective validation studies are needed to determine the cut points of PSA DT. Optimal time intervals for calculation and optimal thresholds are still to be determined
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
Combining static and dynamic analysis for the verification of Information Flow Security in Concurrent Programs
No full textUnwinding conditions provide a general framework for the definition of security properties. They basically depend on the operational semantics and on the (low level) observational equivalence of the specification language under consideration. Hence, unwinding conditions are quite natural also in the case of concurrent imperative languages.
Unfortunately, they are usually undecidable because of the presence of both infinite states and arithmetic operations over the integers. In this context type systems and other static analysis techniques introduced in the literature can be seen as sufficient conditions to prove unwinding-based security
properties. In order to increment the precision of the static analysis, we combine a static proof system with dynamic verification techniques and apply it for the analysis of a basic imperative concurrent language. In particular, we exploit first-order formulae over the reals to both approximate the computation over the integers and symbolically represent an infinite number of states. The proposed first-order formulae mime the operational semantics of the non-recursive fragment of our language. The main issues at this point concern:
(1) how can we bound the computational complexity of our method? (2) how can we introduce a dynamic verification component also for recursion? (3) which extensions of the concurrent imperative language should we consider first
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