Literatura académica sobre el tema "Blackwell determinacy"

Games of infinite length and perfect information have been studied for many years. There are numerous determinacy results for these games, and there is a wide body of work on consequences of their determinacy.Except for games with very special payoff functions, games of infinite length and imperfect information have been little studied. In 1969, David Blackwell [1] introduced a class of such games and proved a determinacy theorem for a subclass. During the intervening time, there has not been much progress in proving the determinacy of Blackwell's games. Orkin [17] extended Blackwell's result to a slightly wider class. Blackwell [2] found a new proof of his own result. Maitra and Sudderth [9, 10] improved Blackwell's result in a different direction from that of Orkin and also generalized to the case of stochastic games. Recently Vervoort [18] has obtained a substantial improvement. Nevertheless, almost all the basic questions have remained open.In this paper we associate with each Blackwell game a family of perfect information games, and we show that the (mixed strategy) determinacy of the former follows from the (pure strategy) determinacy of the latter. The complexity of the payoff function for the Blackwell game is approximately the same as the complexity of the payoff sets for the perfect information games. In particular, this means that the determinacy of Blackwell games with Borel measurable payoff functions follows from the known determinacy of perfect information games with Borel payoff sets.

ABSTRACT All flavivirus genomes contain a 3′terminal stem-loop secondary structure (3′SL) formed by the most downstream ∼100 nucleotides (nt) of the viral RNA. The 3′SL is required for virus replication and has been shown to bind both virus-coded and cellular proteins. Results of the present study using an infectious DNA for WN virus strain 956 initially demonstrated that the dengue virus serotype 2 (DEN2) 3′SL nucleotide sequence could not substitute for that of the WN 3′SL to support WN genome replication. To determine what WN virus-specific 3′SL nucleotide sequences were required for WN virus replication, WN virus 3′SL nucleotide sequences were selectively deleted and replaced by analogous segments of the DEN2 3′SL nucleotide sequence such that the overall 3′SL secondary structure was not disrupted. Top and bottom portions of the WN virus 3′SL were defined according to previous studies (J. L. Blackwell and M. A. Brinton, J. Virol. 71:6433-6444, 1997; L. Zeng, L., B. Falgout, and L. Markoff, J. Virol. 72:7510-7522, 1998). A bulge in the top portion of the long stem of the WN 3′SL was essential for replication of mutant WN RNAs, and replication-defective RNAs failed to produce negative strands in transfected cells. Introduction of a second bulge into the bottom portion of the long stem of the wild-type WN 3′SL markedly enhanced the replication competence of WN virus in mosquito cells but had no effect on replication in mammalian cells. This second bulge was identified as a host cell-specific enhancer of flavivirus replication. Results suggested that bulges and their topological location within the long stem of the 3′SL are primary determinants of replication competence for flavivirus genomes.

An information on the results of the microbiological analysis of xenic cultures of green (<i>Chlorophyta</i>) and charophytes (<i>Charophyta</i>) algae is given. Algal xenic cultures are regarded as communities (consortia) of heterogeneous organisms connected with each other by trophic and topic interactions and composed of a center nucleus (autotrophic algae of one species) and consorts (several species of heterotrophic bacteria). Twelve algal xenic cultures of freshwater (<i>Сhlorella vulgaris</i> Beij., <i>Coelastrum</i> <i>rugosum</i> (P.G. Richt.,<i> Tetradesmus dimorphus</i> (Turpin) M.J.Wynne) and aerophitic (<i>Klebsormidium flaccidum</i> (Kütz.) Silva, Mattox et Blackwell) algae from the collection of M.G. Kholodny Institute of Botany NAS of Ukraine were used in investigations. Each species was represented by three strains isolated in 1961–2018 years from the territories of Ukraine and other countries of Eurasia. Overall, 82 bacterial strains were isolated and identified according to some phenotypic (morphological, chemotaxonomic, physiological and chemical) features. The study revealed complexes of four types which consisted 7 species of bacterial consorts. A qualitative composition of complexes was the same in cultures (strains) of one certain algal species but strictly different in cultures of another algal species. Although, some bacterial species were found in several complexes of different type. It is evident a tight association the heterotrophic bacterial consorts with the autotrophic determinant of consortia and conforms the consortium character of algal-bacterial communities in general. It was proposed an express method based on the use of a numerical system for morphological evaluation of bacterial colonies in preliminary study peculiarities, features and functions of consortia.

We consider multiplayer stochastic games with finitely many players and actions, and countably many states, in which the payoff of each player is a bounded and Borel-measurable function of the infinite play. By using a generalization of the technique of Martin [Martin DA (1998) The determinacy of Blackwell games. J. Symb. Log. 63(4):1565–1581] and Maitra and Sudderth [Maitra A, Sudderth W (1998) Finitely additive stochastic games with Borel measurable payoffs. Internat. J. Game Theory 27:257–267], we show four different existence results. In each stochastic game, it holds for every [Formula: see text] that (i) each player has a strategy that guarantees in each subgame that this player’s payoff is at least his or her maxmin value up to [Formula: see text], (ii) there exists a strategy profile under which in each subgame each player’s payoff is at least his or her minmax value up to [Formula: see text], (iii) the game admits an extensive-form correlated [Formula: see text]-equilibrium, and (iv) there exists a subgame that admits an [Formula: see text]-equilibrium. Funding: This work was supported by the Israel Science Foundation (Nos. 217/17 and 211/22).

O crescimento do mercado turístico brasileiro e o interesse do consumidor pela prática de turismo de aventura e ecoturismo (BRASIL, 2012a) torna pertinente a investigação acerca do comportamento do turista como consumidor de produtos e serviços. Assim, conhecer as variáveis de influência sobre o comportamento de compra do turista é importante para que as empresas possam orientar suas ofertas para o mercado e qualificar seus produtos e serviços de acordo com os desejos e as necessidades do consumidor (ENGEL; BLACKWELL; MINIARD, 2000). Para que seja possível entender o processo decisório de um serviço tão complexo quanto o turismo é preciso considerar os fatores internos e externos ao indivíduo que influenciam essas decisões (SWARBROOKE; HORNER, 2002). Para isso, este trabalho teve como objetivo identificar os principais fatores que influenciam a intenção de compra do turista de aventura e ecoturismo, fundamentando-se no modelo de Estímulo-Resposta do Comportamento do Consumidor de Middleton (1994). O trabalho utilizou-se de metodologia qualitativa e exploratória, entrevistando 10 indivíduos da cidade de Belo Horizonte que costumam efetuar viagens com propósitos de ecoturismo e turismo de aventura. De acordo com os resultados encontrados, os principais fatores que influenciam o comportamento de consumo desses turistas são: os grupos de referência, a imagem que o indivíduo tem de determinado destino e a possibilidade de contato com o meio ambiente. Além disso, o estudo apontou a preferência por viagens organizadas de maneira independente em detrimento das organizadas por agências, principalmente pelos consumidores mais jovens entrevistados, devido à importância aferida à liberdade e a flexibilidade durante esse tipo de viagem. Factors influencing intention to purchase ecotourism and adventure tourism trips ABSTRACT The growth of the Brazilian tourism market and the interest about adventure tourism and ecotourism practices from the consumer (BRASIL, 2012a) make pertinent an investigation about the tourism behavior as a products and services consumer. Therefore, knowing the variables of influence about the tourist buying behavior is important because companies can steer their offerings to market and qualify their products and services according to the desires and needs of consumers (ENGEL; BLACKWELL; MINIARD, 2000). To be able to understand the decision-making process of a service as complex as tourism is necessary to take into account internal and external factors to the individual that influence these decisions (SWARBROOKE; HORNER, 2002). To achieve this, this paper aimed at identifying the main factors that influence the purchase intention of the ecotourism and adventure tourists. The research is based on the Stimulus-Response of Consumer Behavior Model, proposed by Middleton (1994). The study used a qualitative and exploratory methodology, interviewing 10 individuals from the city of Belo Horizonte who usually make trips for purposes of ecotourism and adventure tourism. According to the results, the main factors that influence consumer behavior in adventure tourism and ecotourism are: reference groups, the image that the individual have of a certain destination, the interest in sports practices and contact with the environment. In addition, the study showed a preference for independent travel rather than trips organized by agencies, especially by younger consumers surveyed, due to the importance they give for freedom and flexibility for this kind of trip. KEYWORDS: Consumer Behavior; Ecotourism; Adventure Tourism; Decision-making Process.

On étudie des jeux à deux joueuses (A et B) sur des graphes. À partir d'un état du graphe, les joueuses interagissent pour aller d'un état à un autre.Ceci induit une suite infinie d'états à laquelle une fonction de gain mesurable associe une valeur dans [0, 1]. La Joueuse A (resp. B) tente de maximiser (resp.minimiser) l'espérance de cette fonction de gain.Les jeux à tours, i.e. les jeux tels qu'à chaque état une seule joueuse choisit(une loi de probabilités sur) l'état suivant, ont de nombreuses bonnes propriétés.Par exemple, dans tous les jeux à tours perd/gagne déterministes, une joueuse a une stratégie gagnante. De plus, dans les jeux de parité à tours finis, les deux joueuses ont des stratégies optimales positionnelles. A contrario, les jeux concurrents, i.e. les jeux tels qu'à chaque état les deux joueuses concourent au choix d'une loi de probabilité sur les états suivants, se comportent mal. Ainsi, il existe des jeux concurrents de parité déterministes tels que : aucune des joueuses n'a de stratégie gagnante ; aucune joueuse n'a de stratégie optimale, même stochastique. De plus, lorsque c'est possible, jouer de manière optimale peut nécessiter une mémoire infinie. Le but de ce manuscrit est d'enrichir notre compréhension du comportement des jeux concurrents. Pour ce faire, on étudie la notion de forme de jeu. Les formes de jeu sont les objets mathématiques qui décrivent les interactions (locales) des joueuses à chaque état d'un jeu concurrent. Les formes de jeu sont définies par un ensemble de stratégies locales par joueuse, un ensemble d'issues et une fonction envoyant une paire d'une stratégie locale par joueuse sur une loi de probabilités sur les issues. Généralement, dans les articles sur les jeux concurrents, les interactions locales sont des formes de jeu standard (finies) :les ensembles de stratégies locales sont des lois de probabilités sur les ensembles(finis) d'actions sous-jacents. Ici, on définie des formes de jeu plus générales,que l'on appelle formes de jeu arbitraires. Certains des résultats établis dans ce manuscrit supposent que les interactions locales sont standard, tandis que les autres ne font pas de telles hypothèses.Premièrement, on prouve des résultats généraux sur les jeux concurrents,avec très peu d'hypothèses sur les fonctions de gain et les interactions locales.En particulier, on considère un résultat crucial sur les jeux concurrents : la détermination de Blackwell de Martin, qui peut être énoncé comme suit. Soit un jeu concurrent dont toutes les interactions locales sont standards finies.Depuis chaque état, il existe une valeur u dans [0, 1] telle que les stratégies de la Joueuse A (resp. B) peuvent garantir que l'espérance de la fonction de gain est au moins (resp. au plus) égal à n'importe quel seuil en-dessous(resp. au-dessus) de u. On généralise ce résultat aux jeux dont les formes de jeu sont arbitraires et en déduisons d'autres résultats sur les jeux concurrents. On prouve également d'autres résultats sur les jeux concurrents, en particulier sur les stratégies optimales en sous-jeu. Deuxièmement, on étudie le comportement des jeux de parité concurrents finis en termes d'existence et de nature des stratégies (presque) optimales (en sous-jeu), avec très peu d'hypothèses sur les interactions locales.Troisièmement, on définie des ensembles de jeux concurrents qui ont certaines des propriétés des jeux à tours tout en étant plus généraux que les jeux à tours. Ainsi, étant donné une propriété souhaitable des jeux concurrents, oncaractérise tout d'abord les formes de jeu qui garantissent que tous les jeuxsimples qui les utilisent comme interactions locales satisfont cette propriété. Oncaractérise ainsi les formes de jeu qui se comportent bien individuellement. Onmontre ensuite que tous les jeux concurrents qui utilisent ces formes de jeucomme interactions locales satisfont également cette propriété. Ces formes de jeux se comportent également bien collectivement
We study games played by two players, Player A and Player B, on a graph. Starting from a state of the graph, the players interact to move from state to state. This induces an infinite sequence of states, which is mapped to a value in [0, 1] by a measurable payoff function. Player A (resp. B) tries to maximize (resp. minimize) the expected value of this payoff function.Turn-based games, i.e. games where at each state only one player chooses a (probability distribution over) successor state, enjoy many nice properties.For instance, in all deterministic win/lose turn-based games, from each state,one of the players has a winning strategy. In addition, in finite turn-based parity games, both players have positional optimal strategies from each state.By contrast, concurrent games, i.e. games where at each state both players interact concurrently, i.e. simultaneously, to generate a probability distributionover successor states, behave much more poorly. Indeed, there are very simple deterministic concurrent parity games such that: neither player has a winning strategy; neither player has an optimal strategy, even a stochastic one. Inaddition, when optimal strategies do exist, they may require infinite memory. The goal of this dissertation is to give significant insight on how concurrent games behave. To do so, we study the notion of game form. Game forms arethe mathematical objects that describe the (local) interactions of the players at each state of a concurrent game. Game forms are defined by a set of local strategies per player, a set of outcomes and a function mapping a pair of one local strategy per player to a probability distribution over outcomes. Generally,in the literature on concurrent games, local interactions are standard (finite)game forms: the sets of local strategies are distributions over underlying (finite) sets of actions. In this dissertation, we define and study more general gameforms, which we call arbitrary game forms. Some of the results we prove hold even with arbitrary local interactions, the others use a standard assumption onthe local interactions involved.First, we prove general results on concurrent games, with very few assumptions on the payoff functions and local interactions involved. In particular, we consider a crucial result on concurrent games: Martin's result on Blackwell determinacy, which can be stated as follows. Consider a concurrent game whereall local interactions are standard finite. From each state, there is a value u in[0, 1] such that Player A's (resp. B's) strategies can guarantee that the expected value of the measurable payoff function is above (resp. below) any threshold below (resp. above) u. We generalize this result to games with arbitrary gameforms. We deduce from this generalization other results on concurrent games,possibly using standard local interactions, which could not have been obtained directly from the original result by Martin. We also prove other results on concurrent games, in particular results related to subgame optimal strategies.Second, we study how finite-state concurrent parity games behave in termsof existence and nature of (almost and/or subgame) optimal strategies, with very few assumptions on the local interactions involved.Third, we define subsets of concurrent games that enjoy some of the nice properties of turn-based games while being more general than turn-based games.These subsets are constructed via local-global transfers, which is a novel approach. Specifically, given a desirable property on concurrent games, we first characterize the game forms that ensure that all simple games using them aslocal interactions satisfy this property. Thus, we characterize the game formsthat behave well individually. We then show that all concurrent games that use these game forms as local interactions also satisfy this property. Thus, we show that these game forms also behave well collectively, hence globally