1,721,016 research outputs found
Finite State Verification for the Asynchronous Pi-Calculus
No full textThe pi-calculus is a development of CCS that has the ability of communicating channel names. The asynchronous pi-calculus is a variant of the pi-calculus where message emission is non-blocking.
Finite state verification is problematic in this context, since even very simple asynchronous pi-processes give rise to infinite-state behaviors. This is due to phenomena that are typical of calculi with name passing and to phenomena that are peculiar of asynchronous calculi.
We present a finite-state characterization of a family of finitary asynchronous pi-processes by exploiting History Dependent transition systems with Negative transitions (HDN), an extension of labelled transition systems particularly suited for dealing with concurrent calculi with name passing. We also propose an algorithm based on HDN to verify asynchronous bisimulation for finitary pi-processe
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
Structured coalgebras and minimal HD-automata for the pi-calculus
No full textThe coalgebraic framework developed for the classical process algebras, and in particular its advantages concerning minimal realizations, does not fully apply to the pi-calculus, due to the constraints on the freshly generated names that appear in the bisimulation. In this paper we propose to model the transition system of the pi-calculus as a coalgebra on a category of name permutation algebras and to define its abstract semantics as the final coalgebra of such a category. We show that permutations are sufficient to represent in an explicit way fresh name generation, thus allowing for the definition of minimal realizations. We also link the coalgebraic semantics with a slightly improved version of history dependent (HD) automata, a model developed for verification purposes, where states have local names and transitions are decorated with names and name relations. HD-automata associated with agents with a bounded number of threads in their derivatives are finite and can be actually minimized. We show that the bisimulation relation in the coalgebraic context corresponds to the minimal HD-automaton. (c) 2005 Elsevier B.V. All rights reserved
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
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