1,720,975 research outputs found
Regular processes and timed automata
Get PDFIn [10], an algebra for timed automata has been introduced. In this article, we introduce a syntactic characterisation of finite timed automata in terms of that process algebra. We show that regular processes, i.e., processes defined using finitely many guarded recursive equations, are as expressive as finite timed automata. The proof uses only the axiom system and unfolding of recursive equations. Since the proofs are basically algorithms, we also provide an effective method to translate from one model into the other. A remarkable corollary of these proofs is that regular recursive specifications may need one clock less than timed automata in order to represent the same process
Extending LOTOS with time: A true concurrency perspective
No full textAn ongoing restandardisation activity is currently extending the OSI specification language LOTOS with quantitative time. We give an alternative perspective on this activity. We highlight a very simple but expressive timed LOTOS enhancement which is based on time intervals. The main point at which we depart from the standard approach to extending LOTOS with time, is that we employ a true concurrency semantics. We present a semantics based on a time extended bundle event structures. We give a full semantics for relating our timed LOTOS to timed bundle event structures. A fixed point theory is defined and finally, we describe how urgency can be supported in the language
Denotational semantics for timed testing
Get PDFIn this paper we present a denotational semantics for a timed process algebra, which is fully abstract with respect to the must testing semantics previously developed [Lla96,LdFN96]. The domain of semantic processes is made up of consistent sets of barbs, which generalize the notion of acceptance sets, in such a way that the actions that are offered but not taken in each state are also recorded. the main difficulty when defining this denotational semantics has been that the natural ordering between semantic processes cannot be proved to be complete. So an alternative stronger complete ordering has to be considered, which is proved to be consistent with the original one, in the sense that lubs of chains with respect to the new ordering are also lubs with respect to the original one.Sección Deptal. de Sistemas Informáticos y ComputaciónFac. de Ciencias MatemáticasInstituto de Matemática Interdisciplinar (IMI)TRUEpu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
A sound and complete proof system for probabilistic processes
Get PDFIn this paper we present a process algebra model of probabilistic communicating processes based on classical CSP. To define our model we have replaced internal non-determinism by generative probabilistic choices, and external non-determinism by reactive probabilistic choices, with the purpose of maintaining the meaning of the classical CSP operators, once generalized in a probabilistic way. Thus we try to keep valid, as far as possible, the laws of CSP. This combination of both internal and external choice makes strongly difficult the definition of a probabilistic version of CSP. In fact, we can find in the current literature quite a number of papers on probabilistic processes, but only in a few of them internal and external choices are combined, trying to preserve their original meaning.
Starting with a denotational semantics where the corresponding domain is a set of probabilistic trees with two kinds of nodes, representing the internal and external choices, we define a sound and complete proof system, with very similar laws to those of the corresponding CSP.Sección Deptal. de Sistemas Informáticos y ComputaciónFac. de Ciencias MatemáticasInstituto de Matemática Interdisciplinar (IMI)TRUEpu
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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