1,721,840 research outputs found
Dynamic Games in Novel Networks: Guest Editors' Forewords
No full textAn increasing number of man-made networked systems, such as social networks and online platforms, govern the interactions between players through predefined actions such as the possibility of sharing informations, accessing a service, express opinions or preferences. Ultimately, the evolution of such systems is determined by strategic interactions developing over complex structures. Strategic interactions, which take place at the local level, e.g., in a node’s neighborhood, finally emerge to determine global system configurations. This special issue has collected a set of contributions, which are inspired by this general framework.
In this broad context, two contributions in this special issue are focused on network effects. In particular, coordination games are used as atomic representation of imitation behavior of players which may propagate or not in an interconnected system, e.g., across a social network. Khan et al. study the influence of network topology on the emergence of efficient equilibria in coordination games and explore numerically the convergence time to such configurations. Conversely, Peeters et al. focus on the effect of information diffusion by considering global interaction and confine imitation to the neighborhood of players.
The individual choice of customers of a queuing system is studied in the paper authored by Wiecek and Altman, where the authors develop a theory which captures existence of threshold-type policies in the decision to join or not to join a queue. The authors also study the role of the amount of information about the queue backlog available at customers upon their arrival to the queue.
Shimkin and Altman study a game of timing between a random number of content creators, who compete for position and exposure time over a shared medium such as an online classified list. Contents are ordered according to their submission times, with more recent submissions displayed at the top positions. Content creators have to choose the submission time of their contents within a finite time interval, with the goal of each creator to maximize the total expected exposure of this content. The authors analyze the symmetric equilibrium of the game, characterize it in terms of a differential boundary value problem and devise a numerical scheme for its computation.
The role of homophily is studied in the work of Bagagiolo, where the players of a social network tend to align their opinions to the mainstream opinion, i.e., the opinion of the majority. The role of activation costs in order to align to the mainstream opinion is studied through a meanfield game model.
Petrosyan and Sedakov connect the network formation concept to a dynamic cooperative framework: The result of bailing out from a coalition has the meaning of players stopping their activity in the game, removing all the links as well as the ability to establish new ones. The authors hence study the existence of a cooperative solution which is subgame consistent.
Finally, the effect of network heterogeneity on evolutionary dynamics is studied by Zhang et al. The evolution of strategies depends on the neighbors’ strategies, and the authors introduce an approximated replicator equation that involves mean value and the variance of the degree distribution. They show that such equation predicts correct behaviors observed in the literature
Many-body localization and quench dynamics in random spin chains, a real space RG perspective
No full textAltman, E.. (2012). Many-body localization and quench dynamics in random spin chains, a real space RG perspective. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/131510
Default recovery rates in credit risk modelling: A review of the literature and empirical evidence
No full textEvidence from many countries in recent years suggests that collateral values and recovery rates (RRs) on corporate defaults can be volatile and, moreover, that they tend to go down just when the number of defaults goes up in economic downturns. This link between RRs and default rates has traditionally been neglected by credit risk models, as most of them focused on default risk and adopted static loss assumptions, treating the RR either as a constant parameter or as a stochastic variable independent from the probability of default (PD). This traditional focus on default analysis has been partly reversed by the recent significant increase in the number of studies dedicated to the subject of recovery-rate estimation and the relationship between default and RRs. This paper presents a detailed review of the way credit risk models, developed during the last 30 years, treat the RR and, more specifically, its relationship with the PD of an obligor. Recent empirical evidence concerning this issue is also presented and discussed. © Banca Monte dei Paschi di Siena SpA, 2004
Amministrazione Straordinaria e previsione dell’insolvenza:un’applicazione dello Z score alle imprese in procedura
No full textIl presente studio ha l'obiettivo di verficare l'accuratezza per l'Italia del più celebre dei modelli di previsione dell'insolvenza, lo Z Score di Altman, tramite un test sulle imprese assoggettate ad Amministrazione Straordinaria nel periodo 2000-2010. I risultati confermano una buona efficacia previsiva della variante nota come Z'', ancorché le peculiarità italiane richiederebbero l'elaborazione di parametri ad hoc
La previsione dell'insolvenza: l'applicazione dello Z Score alle imprese in Amministrazione Straordinaria
No full textL'articolo si pone l'obiettivo di verificare l'accuratezza dello Z score per la previsione dell'insolvenza in Italia, tramite un test sul campione delle imprese assoggettate alla procedura di amministrazione straordinaria nel periodo 2000-2010. I risultati confermano una buona efficacia previsiva nonostante le peculiarità italiane richiedano parametri ad hoc
The Impact of Channel Randomness on Coverage and Connectivity of Ad Hoc and Sensor Networks
No full text
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
Activation games in online dating platforms
No full textIn this paper we describe a model for the activation level of users in online dating platforms (ODPs). Such popular systems are conceived in order to match individuals from two groups of potential mates. The business of such platforms pivots around the customers' expectancy to get in contact with their future dates: upon the payment of a fee to the platform owner, ODPs provide specific tools to improve reach and visibility.However, ODPs require a critical number of active users in order to sustain their operations (and their business). Customers of the platform trade off on the price for being more visible and attract mates' contacts. A user becomes inactive if he or she is not contacted by others for some time: being contacted by potential mates acts as an activation signal. The aim of our analysis is to propose a game theoretical framework to capture such a complex activation problem in strategic form. We unveil the structure of Nash equilibria and we further derive a Stackelberg formulation. The latter is a hierarchical game where the platform owner aims at maximizing profits while preserving the ODP activity level above a critical epidemic threshold
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
- …
