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Folk Theorem (game Theory)
In game theory, folk theorems are a class of theorems describing an abundance of Nash equilibrium payoff profiles in repeated games . The original Folk Theorem concerned the payoffs of all the Nash equilibria of an infinitely repeated game. This result was called the Folk Theorem because it was widely known among game theorists in the 1950s, even though no one had published it. Friedman's (1971) Theorem concerns the payoffs of certain subgame-perfect Nash equilibria (SPE) of an infinitely repeated game, and so strengthens the original Folk Theorem by using a stronger equilibrium concept: subgame-perfect Nash equilibria rather than Nash equilibria. The Folk Theorem suggests that if the players are patient enough and far-sighted (i.e. if the discount factor \delta \to 1 ), then repeated interaction can result in virtually any average payoff in an SPE equilibrium. "Virtually any" is here technically defined as "feasible" and "individually rational". For example, in the one-shot Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Game Theory
Game theory is the study of mathematical models of strategic interactions among rational agents. Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbs1 Chapter-preview links, ppvii–xi It has applications in all fields of social science, as well as in logic, systems science and computer science. Originally, it addressed two-person zero-sum games, in which each participant's gains or losses are exactly balanced by those of other participants. In the 21st century, game theory applies to a wide range of behavioral relations; it is now an umbrella term for the science of logical decision making in humans, animals, as well as computers. Modern game theory began with the idea of mixed-strategy equilibria in two-person zero-sum game and its proof by John von Neumann. Von Neumann's original proof used the Brouwer fixed-point theorem on continuous mappings into compact convex sets, which became a standard method in game theory and mathema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgame Perfect
In game theory, a subgame perfect equilibrium (or subgame perfect Nash equilibrium) is a refinement of a Nash equilibrium used in dynamic games. A strategy profile is a subgame perfect equilibrium if it represents a Nash equilibrium of every subgame of the original game. Informally, this means that at any point in the game, the players' behavior from that point onward should represent a Nash equilibrium of the continuation game (i.e. of the subgame), no matter what happened before. Every finite extensive game with perfect recall has a subgame perfect equilibrium. Perfect recall is a term introduced by Harold W. Kuhn in 1953 and ''"equivalent to the assertion that each player is allowed by the rules of the game to remember everything he knew at previous moves and all of his choices at those moves"''. A common method for determining subgame perfect equilibria in the case of a finite game is backward induction. Here one first considers the last actions of the game and determines w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overtaking
Overtaking or passing is the act of one vehicle going past another slower moving vehicle, travelling in the same direction, on a road. The lane used for overtaking another vehicle is often a passing lane farther from the road shoulder which is to the left in places that drive on the right and to the right in places that drive on the left. Rules of overtaking In English-speaking countries On a single-carriageway/undivided-highway road, the lane used for overtaking is often the same lane that is used by oncoming traffic. An overtaking vehicle must be able to see clearly ahead of them for the entire overtaking manoeuvre plus a margin of error. For example, in New Zealand it's instructed in the Road Code that an overtaking driver must be able to see at least of clear road in front of them as they finish the passing manoeuvre. In the UK, guidance for passing and overtaking is given in rules 162-169 of the Highway Code. In some jurisdictions, the "overtaking zone" is indicated b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PPAD (complexity)
In computer science, PPAD ("Polynomial Parity Arguments on Directed graphs") is a complexity class introduced by Christos Papadimitriou in 1994. PPAD is a subclass of TFNP based on functions that can be shown to be total by a parity argument. The class attracted significant attention in the field of algorithmic game theory because it contains the problem of computing a Nash equilibrium: this problem was shown to be complete for PPAD by Daskalakis, Goldberg and Papadimitriou with at least 3 players and later extended by Chen and Deng to 2 players.*. Definition PPAD is a subset of the class TFNP, the class of function problems in FNP that are guaranteed to be total. The TFNP formal definition is given as follows: :A binary relation P(''x'',''y'') is in TFNP if and only if there is a deterministic polynomial time algorithm that can determine whether P(''x'',''y'') holds given both ''x'' and ''y'', and for every ''x'', there exists a ''y'' such that P(''x'',''y'') holds. Subclasses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligopoly
An oligopoly (from Greek ὀλίγος, ''oligos'' "few" and πωλεῖν, ''polein'' "to sell") is a market structure in which a market or industry is dominated by a small number of large sellers or producers. Oligopolies often result from the desire to maximize profits, which can lead to collusion between companies. This reduces competition, increases prices for consumers, and lowers wages for employees. Many industries have been cited as oligopolistic, including civil aviation, electricity providers, the telecommunications sector, Rail freight markets, food processing, funeral services, sugar refining, beer making, pulp and paper making, and automobile manufacturing. Most countries have laws outlawing anti-competitive behavior. EU competition law prohibits anti-competitive practices such as price-fixing and manipulating market supply and trade among competitors. In the US, the United States Department of Justice Antitrust Division and the Federal Trade Commission are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franklin Fisher
Franklin Marvin Fisher (December 13, 1934 – April 29, 2019) was an American economist. He taught economics at the Massachusetts Institute of Technology from 1960 to 2004. Biography Fisher attended Harvard University, where he was inducted into Phi Beta Kappa in 1955 and received a Bachelor of Arts degree (''summa cum laude'') in 1956, followed by a Master's degree in 1957 and a Doctor of Philosophy, Ph.D. in Economics from Harvard in 1960. His doctoral thesis was entitled ''A Priori Information and Time Series Analysis''. Fisher married Ellen Paradise Fisher in 1958. They had three children and eight grandchildren. He was Teaching Fellow at Harvard from 1956 to 1957, Junior Fellow of the Harvard Society of Fellows, Society of Fellows at Harvard (1957–59), Assistant Professor of Economics at the University of Chicago (1959–60), Assistant Professor of Economics at MIT (1960–62), Associate Professor of Economics at MIT (1962–65), and Professor of Economics at MIT from 1965 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Social Norm
Social norms are shared standards of acceptance, acceptable behavior by groups. Social norms can both be informal understandings that govern the behavior of members of a society, as well as be codified into wikt:rule, rules and laws. Social normative influences or social norms, are deemed to be powerful drivers of human behavioural changes and well organized and incorporated by major theories which explain human behaviour. Institutions are composed of multiple norms. Norms are shared social beliefs about behavior; thus, they are distinct from "ideas", "Attitude (psychology), attitudes", and "Value (ethics), values", which can be held privately, and which do not necessarily concern behavior. Norms are contingent on context, social group, and historical circumstances. Scholars distinguish between regulative norms (which constrain behavior), constitutive norms (which shape interests), and prescriptive norms (which prescribe what actors ''ought'' to do). The effects of norms can be det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taboo
A taboo or tabu is a social group's ban, prohibition, or avoidance of something (usually an utterance or behavior) based on the group's sense that it is excessively repulsive, sacred, or allowed only for certain persons.''Encyclopædia Britannica Online''.Taboo. Encyclopædia Britannica Inc., 2012. Retrieved 21 Mar. 2012 Such prohibitions are present in virtually all societies. Taboos may be prohibited explicitly, for example within a legal system or religion, or implicitly, for example by social norms or conventions followed by a particular culture or organization. Taboos are often meant to protect the individual, but there are other reasons for their development. An ecological or medical background is apparent in many, including some that are seen as religious or spiritual in origin. Taboos can help use a resource more efficiently, but when applied to only a subsection of the community they can also serve to suppress said subsection of the community. A taboo acknowledged by a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tradition
A tradition is a belief or behavior (folk custom) passed down within a group or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or impractical but socially meaningful clothes (like lawyers' wigs or military officers' spurs), but the idea has also been applied to social norms such as greetings. Traditions can persist and evolve for thousands of years—the word ''tradition'' itself derives from the Latin ''tradere'' literally meaning to transmit, to hand over, to give for safekeeping. While it is commonly assumed that traditions have an ancient history, many traditions have been invented on purpose, whether that be political or cultural, over short periods of time. Various academic disciplines also use the word in a variety of ways. The phrase "according to tradition", or "by tradition", usually means that whatever information follows is known only by oral tradition, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthropology
Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of behavior, while cultural anthropology studies cultural meaning, including norms and values. A portmanteau term sociocultural anthropology is commonly used today. Linguistic anthropology studies how language influences social life. Biological or physical anthropology studies the biological development of humans. Archaeological anthropology, often termed as 'anthropology of the past', studies human activity through investigation of physical evidence. It is considered a branch of anthropology in North America and Asia, while in Europe archaeology is viewed as a discipline in its own right or grouped under other related disciplines, such as history and palaeontology. Etymology The abstract noun ''anthropology'' is first attested in reference t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overtaking Criterion
In economics, the overtaking criterion is used to compare infinite streams of outcomes. Mathematically, it is used to properly define a notion of optimality for a problem of optimal control on an unbounded time interval. Often, the decisions of a policy-maker may have influences that extend to the far future. Economic decisions made today may influence the economic growth of a nation for an unknown number of years into the future. In such cases, it is often convenient to model the future outcomes as an infinite stream. Then, it may be required to compare two infinite streams and decide which one of them is better (for example, in order to decide on a policy). The overtaking criterion is one option to do this comparison. Notation X is the set of possible outcomes. E.g., it may be the set of positive real numbers, representing the possible annual gross domestic product. It is normalized X^\infty is the set of infinite sequences of possible outcomes. Each element in X^\infty is of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pareto Efficient
Pareto efficiency or Pareto optimality is a situation where no action or allocation is available that makes one individual better off without making another worse off. The concept is named after Vilfredo Pareto (1848–1923), Italian civil engineer and economist, who used the concept in his studies of economic efficiency and income distribution. The following three concepts are closely related: * Given an initial situation, a Pareto improvement is a new situation where some agents will gain, and no agents will lose. * A situation is called Pareto-dominated if there exists a possible Pareto improvement. * A situation is called Pareto-optimal or Pareto-efficient if no change could lead to improved satisfaction for some agent without some other agent losing or, equivalently, if there is no scope for further Pareto improvement. The Pareto front (also called Pareto frontier or Pareto set) is the set of all Pareto-efficient situations. Pareto originally used the word "optimal" for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
