Tit-for-tat
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Tit-for-tat
Tit for tat is an English saying meaning "equivalent retaliation". It developed from "tip for tap", first recorded in 1558. It is also a highly effective strategy in game theory. An agent using this strategy will first cooperate, then subsequently replicate an opponent's previous action. If the opponent previously was cooperative, the agent is cooperative. If not, the agent is not. Game theory Tit-for-tat has been very successfully used as a strategy for the iterated prisoner's dilemma. The strategy was first introduced by Anatol Rapoport in Robert Axelrod's two tournaments, held around 1980. Notably, it was (on both occasions) both the simplest strategy and the most successful in direct competition. An agent using this strategy will first cooperate, then subsequently replicate an opponent's previous action. If the opponent previously was cooperative, the agent is cooperative. If not, the agent is not. This is similar to reciprocal altruism in biology. History The term develo ...
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Iterated Prisoner's Dilemma
The Prisoner's Dilemma is an example of a game analyzed in game theory. It is also a thought experiment that challenges two completely rational agents to a dilemma: cooperate with their partner for mutual reward, or betray their partner ("defect") for individual reward. This dilemma was originally framed by Merrill Flood and Melvin Dresher while working at RAND in 1950. Albert W. Tucker appropriated the game and formalized it by structuring the rewards in terms of prison sentences and named it "prisoner's dilemma". William Poundstone in his 1993 book ''Prisoner's Dilemma'' writes the following version:Two members of a criminal gang are arrested and imprisoned. Each prisoner is in solitary confinement with no means of speaking to or exchanging messages with the other. The police admit they don't have enough evidence to convict the pair on the principal charge. They plan to sentence both to two years in prison on a lesser charge. Simultaneously, the police offer each prisoner a ...
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Handshake (Workshop Cologne '06)
A handshake is a globally widespread, brief greeting or parting tradition in which two people grasp one of each other's like hands, in most cases accompanied by a brief up-and-down movement of the grasped hands. Customs surrounding handshakes are specific to cultures. Different cultures may be more or less likely to shake hands, or there may be different customs about how or when to shake hands.Fist bump can pound out flu transmission
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History

The handshake may have originated in prehistory as a demonstration of peaceful intent, since it shows that the hand holds no weapon. Another possibility is that it originated as a symbolic gesture of mutual commitment to an oath or promise: two hands clasping each other represents the sealing of ...
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Protestant
Protestantism is a Christian denomination, branch of Christianity that follows the theological tenets of the Reformation, Protestant Reformation, a movement that began seeking to reform the Catholic Church from within in the 16th century against what its followers perceived to be growing Criticism of the Catholic Church, errors, abuses, and discrepancies within it. Protestantism emphasizes the Christian believer's justification by God in faith alone (') rather than by a combination of faith with good works as in Catholicism; the teaching that Salvation in Christianity, salvation comes by Grace in Christianity, divine grace or "unmerited favor" only ('); the Universal priesthood, priesthood of all faithful believers in the Church; and the ''sola scriptura'' ("scripture alone") that posits the Bible as the sole infallible source of authority for Christian faith and practice. Most Protestants, with the exception of Anglo-Papalism, reject the Catholic doctrine of papal supremacy, ...
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Oxford University Press
Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books by decree in 1586, it is the second oldest university press after Cambridge University Press. It is a department of the University of Oxford and is governed by a group of 15 academics known as the Delegates of the Press, who are appointed by the vice-chancellor of the University of Oxford. The Delegates of the Press are led by the Secretary to the Delegates, who serves as OUP's chief executive and as its major representative on other university bodies. Oxford University Press has had a similar governance structure since the 17th century. The press is located on Walton Street, Oxford, opposite Somerville College, in the inner suburb of Jericho. For the last 500 years, OUP has primarily focused on the publication of pedagogical texts and ...
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Nash Equilibrium
In game theory, the Nash equilibrium, named after the mathematician John Nash, is the most common way to define the solution of a non-cooperative game involving two or more players. In a Nash equilibrium, each player is assumed to know the equilibrium strategies of the other players, and no one has anything to gain by changing only one's own strategy. The principle of Nash equilibrium dates back to the time of Cournot, who in 1838 applied it to competing firms choosing outputs. If each player has chosen a strategy an action plan based on what has happened so far in the game and no one can increase one's own expected payoff by changing one's strategy while the other players keep their's unchanged, then the current set of strategy choices constitutes a Nash equilibrium. If two players Alice and Bob choose strategies A and B, (A, B) is a Nash equilibrium if Alice has no other strategy available that does better than A at maximizing her payoff in response to Bob choosing B, and Bob ...
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Princeton University Press
Princeton University Press is an independent publisher with close connections to Princeton University. Its mission is to disseminate scholarship within academia and society at large. The press was founded by Whitney Darrow, with the financial support of Charles Scribner, as a printing press to serve the Princeton community in 1905. Its distinctive building was constructed in 1911 on William Street in Princeton. Its first book was a new 1912 edition of John Witherspoon's ''Lectures on Moral Philosophy.'' History Princeton University Press was founded in 1905 by a recent Princeton graduate, Whitney Darrow, with financial support from another Princetonian, Charles Scribner II. Darrow and Scribner purchased the equipment and assumed the operations of two already existing local publishers, that of the ''Princeton Alumni Weekly'' and the Princeton Press. The new press printed both local newspapers, university documents, ''The Daily Princetonian'', and later added book publishing to it ...
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Discounted Utility
In economics, discounted utility is the utility (desirability) of some future event, such as consuming a certain amount of a good, as perceived at the present time as opposed to at the time of its occurrence. It is calculated as the present discounted value of future utility, and for people with time preference for sooner rather than later gratification, it is less than the future utility. The utility of an event ''x'' occurring at future time ''t'' under utility function ''u'', discounted back to the present (time 0) using discount factor \beta, Is :\beta ^t u(x_t). Since more distant events are less liked, 0 < \beta < 1. Discounted utility calculations made for events at various points in the future as well as at the present take the form :\sum_^T \beta ^t u(x_t), where u(x_t) is the utility of some choice x at time t and ''T'' is the time of the most distant future satisfaction event. Here, since utility comparis ...
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Subgame Perfect Equilibrium
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 determ ...
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Geometric Series
In mathematics, a geometric series is the sum of an infinite number of terms that have a constant ratio between successive terms. For example, the series :\frac \,+\, \frac \,+\, \frac \,+\, \frac \,+\, \cdots is geometric, because each successive term can be obtained by multiplying the previous term by 1/2. In general, a geometric series is written as a + ar + ar^2 + ar^3 + ..., where a is the coefficient of each term and r is the common ratio between adjacent terms. The geometric series had an important role in the early development of calculus, is used throughout mathematics, and can serve as an introduction to frequently used mathematical tools such as the Taylor series, the complex Fourier series, and the matrix exponential. The name geometric series indicates each term is the geometric mean of its two neighboring terms, similar to how the name arithmetic series indicates each term is the arithmetic mean of its two neighboring terms. The sequence of geometric series term ...
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The Evolution Of Cooperation
''The Evolution of Cooperation'' is a 1984 book written by political scientist Robert Axelrod that expands upon paper of the same name written by Axelrod and evolutionary biologist W.D. Hamilton. The book details a theory on the emergence of cooperation between individuals, drawing from game theory and evolutionary biology. Since 2006, reprints of the book have included a foreword by Richard Dawkins and have been marketed as a revised edition. The book provides an investigation into how cooperation can emerge and persist (also known as cooperation theory) as elucidated by the application of game theory. The book provides a detailed explanation of the evolution of cooperation, beyond traditional game theory. Academic literature regarding forms of cooperation that are not easily explained in traditional game theory, especially when considering evolutionary biology, largely took its modern form as a result of Axelrod's and Hamilton's influential 1981 paper and the subsequent book. ...
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Hobbes
Thomas Hobbes ( ; 5/15 April 1588 – 4/14 December 1679) was an English philosopher, considered to be one of the founders of modern political philosophy. Hobbes is best known for his 1651 book ''Leviathan'', in which he expounds an influential formulation of social contract theory. In addition to political philosophy, Hobbes contributed to a diverse array of other fields, including history, jurisprudence, geometry, theology, and ethics, as well as philosophy in general. Biography Early life Thomas Hobbes was born on 5 April 1588 (Old Style), in Westport, now part of Malmesbury in Wiltshire, England. Having been born prematurely when his mother heard of the coming invasion of the Spanish Armada, Hobbes later reported that "my mother gave birth to twins: myself and fear." Hobbes had a brother, Edmund, about two years older, as well as a sister named Anne. Although Thomas Hobbes's childhood is unknown to a large extent, as is his mother's name, it is known that Hobbes's fat ...
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In Memoriam A
IN, In or in may refer to: Places * India (country code IN) * Indiana, United States (postal code IN) * Ingolstadt, Germany (license plate code IN) * In, Russia, a town in the Jewish Autonomous Oblast Businesses and organizations * Independent Network, a UK-based political association * Indiana Northeastern Railroad (Association of American Railroads reporting mark) * Indian Navy, a part of the India military * Infantry, the branch of a military force that fights on foot * IN Groupe , the producer of French official documents * MAT Macedonian Airlines (IATA designator IN) * Nam Air (IATA designator IN) Science and technology * .in, the internet top-level domain of India * Inch (in), a unit of length * Indium, symbol In, a chemical element * Intelligent Network, a telecommunication network standard * Intra-nasal (insufflation), a method of administrating some medications and vaccines * Integrase, a retroviral enzyme Other uses * ''In'' (album), by the Outsiders, 1967 * In ...
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