1,720,994 research outputs found
Réseaux et optimisation pour la gestion de la biodiversité et des services écosystémiques
No full textSolving adaptive sampling problems in graphical models using Markov decision process
No full textIn environmental management problems, decision should ideally rely on knowledge of the whole system. However, due to limited budget, in practice only a small part of the system is sampled and the complete system state is reconstructed from the sampled observations. In this article we consider the situation where the biological system under study is structured and can be modeled as a graphical model. Optimal sampling in such models still raises some methodological questions, like adaptive sampling, or the measure of the quality of a sample in terms of quality of reconstruction. Here, we present a way to formalise these two questions. The sample is chosen as the one which maximises the expected utility of information brought by the observations minus the sample cost.
The utily is derived from the notion of Maximum a Posteriori. This problem is known to be NP-hard. We present how to modelit as a Markov decision process in order to build approximate solution methods based on Reinforcement Learning
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
Possibilistic games with incomplete information
Get PDFBayesian games offer a suitable framework for cardinal games, where the utility degrees are additive in essence. This approach does nevertheless not apply to ordinal games, where the utility degrees do not capture more than a ranking, nor to situations of decision under qualitative uncertainty. The present paper proposes a model of (ordinal) games under possibilistic incomplete information (II-games). It extends two fundamental notions of game theory, namely the concepts of pure Nash equilibrium and secure strategy. It finally proposes a transformation that maps any Π-game to a classical normal form game equivalent in terms of Nash equilibrium
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
Epidémiologie et conservation de la biodiversité : Défis pour la recherche sur les Processus Décisionnels de Markov
Get PDFEpidémiologie et conservation de la biodiversité : Défis pour la recherche sur les Processus Décisionnels de Markov. INRIA Sequel team Seminar
Une approche ordinale de la décision dans l'incertain : axiomatisation, représentation logique et application à la décision séquentielle
No full textLa premi`ere partie de cette th`ese consiste en un ´etat de l’art de la d´ecision dans l’incertain, consid ´er´ee du point de vue de l’Intelligence Artificielle. En premier lieu sont d´ecrites certaines approches classiques de la d´ecision dans l’incertain, dont la th´eorie de l’utilit´e esp´er´ee puis certaines approches non-classiques, num´eriques ou ordinales. Ensuite, nous ´evoquons deux domaines o`u la d´ecision dans l’incertain interagit avec l’IA: Les processus d´ecisionnels Markoviens et leur application `a la planification dans l’incertain et la representation logique des preferences. La seconde partie constitue l’apport sp´ecifique de cette th`ese. Elle est divis´ee en trois sous-parties reprenant les th`emes de la premi`ere partie : 1) Nous ´etudions des crit`eres qualitatifs de d´ecision dans l’incertain prenant leurs valeurs dans une ´echelle finie, totalement ordonn´ee et nous en proposons une justification axiomatique. Ces crit`eres sont bas´es sur une int´egrale de Sugeno qui peut ˆetre consid´er´ee comme une contrepartie qualitative de l’int´egrale de Choquet. Parmi les crit`eres axiomatis´es on retrouve, entre autres, les deux fonctions d’utilit´e qualitative possibiliste propos´ees par Dubois et Prade. 2) Nous ´etudions une contrepartie possibiliste des processus d´ecisionnelsMarkoviens, totalement et partiellement observables et leur application `a la planification sous incertitude et nous proposons un certain nombre d’algorithmes de r´esolution de type “programmation dynamique”. 3) Nous proposons enfin un langage structur´e de repr´esentation des probl`emes de d´ecision sous incertitude qualitative. Ce langage est bas´e sur la logique propositionnelle (valu´ee) et les “syst` emes de maintien de la coh´erence bas´es sur les hypoth`eses” (ATMS). Le langage propos´e s’adapte `a la repr´esentation de probl`emes de d´ecision sous incertitude, non seulement lorsque celle-ci est du type “possibiliste”, mais aussi lorsqu’elle est repr´esent´ee par des “fonctions de croyance”. Des m´ethodes et algorithmes de r´esolution sont propos´es, utilisant des proc´edures de recherche de mod`eles du type Davis et Putnam
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