1,721,101 research outputs found
Psychological Nash equilibria under ambiguity
Full text linkPsychological games aim to represent situations in which players may have belief-dependent moti-vations. In this setting, utility functions are directly dependent on the entire hierarchy of beliefs of each player. On the other hand, the literature on strategic ambiguity in classical games highlights that players may have ambiguous (or imprecise) beliefs about opponents' strategy choices. In this paper, we look at the issue of ambiguity in the framework of simultaneous psychological games by taking into account ambiguous hierarchies of beliefs and study a natural generalization of the psychological Nash equilibrium concept to this framework. We give an existence result for this new concept of equilibrium and provide examples that show that even an infinitesimal amount of ambiguity may alter significantly the equilibria of the game or can work as an equilibrium selection device. Finally, we look at the problem of stability of psychological equilibria with respect to ambiguous trembles on the entire hierarchy of correct beliefs and we provide a limit result that gives conditions so that sequences of psychological equilibria under ambiguous perturbation converge to psychological equilibria of the unperturbed game.(c) 2022 Elsevier B.V. All rights reserved
COOLING WHITE-DWARFS IN GALACTIC GLOBULARS
No full textIn the first part of the paper, we study the evolution of hot horizontal-branch models which miss the asymptotic branch (AGB) phase to produce ''low-mass'' white dwarfs (WDs) with masses of the order of 0.5 M.. One finds that for each given metallicity there exists a maximum value for the mass of the H-rich envelope allowing the models to approach the cooling phase without the onset of CNO H-burning flashes; the larger the metallicity, the lower the mass of such a ''critical envelope.'' Moreover, we find that above log L approximately 1 the cooling rate appears drastically affected by the previous evolutionary history, allowing a meaningful discussion of the cooling laws only below such a luminosity. The dependence of the cooling rates on the mass of the H-rich envelope is investigated for suitable assumptions about the value of this parameter, discussing the contribution of both CNO and p-p H burning to the evolution. The investigation has been further extended to stars with larger He cores, showing that the final cooling structures closely approach available evaluations of post-AGB CO dwarfs, as the result of a convergence toward ''canonical'' self-consistent WD structures. On this basis, we discuss the influence of WD masses on both the cooling rate and the H-R diagram location of the cooling sequence. The application of this theoretical scenario to the WD population in stellar clusters is finally discussed
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
A Dynamic Game of Coalition Formation under Ambiguity
No full textIn a previous paper, we generalized to the
mixed strategy case the c model of coalition formation
(introduced by Hart and Kurz in Econometrica 51(4):1047–
1064, 1983) for situations in which players have ambiguous
expectations about the formation of the coalitions in
which they are not involved; then we analyzed the corresponding
evolutionary games. In this paper, we embody
into the model rationality of the players; it follows that
allowing for mixed strategies makes it impossible to construct
unequivocally a von Neumann–Morgestein expected
utility function coherent (in the sense of de Finetti B in Sul
Significato Soggettivo della Probabilita`, Fundamenta
Mathematicae, T, vol XVIII, pp 298–329, 1931) to every
strategy profile. We find out that if the multiplicity of
coherent beliefs problem is approached by considering
‘‘ambiguity loving’’ players then existence results for
classical static equilibria can be obtained in this model.
Moreover, we provide conditions for the game to be
dynamically playable and we find how the coalition
structure beliefs might evolve coherently (according) to the
evolution of the strategies
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
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