Two players bargain to select a utility allocation in some set X⊂R+2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$X\subset {\mathbb {R}}_+^2$$\end{document}. Bargaining takes place in infinite discrete time, where each period t is divided into two sub-periods. In the first sub-period, the players play a simultaneous-move game to determine that period’s proposer, and bargaining takes place in the second sub-period. Rejection triggers a one-period delay and move to t+1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$t+1$$\end{document}. (...) For every x∈X∩R++2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$x\in X\cap {\mathbb {R}}^2_{++}$$\end{document}, there exists a cutoff δ<1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\delta <1$$\end{document}, such that if at least one player has a discount factor above δ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\delta $$\end{document}, then for every y∈X\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$y\in X$$\end{document} that satisfies y≥x\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$y\ge x$$\end{document} there exists a subgame perfect equilibrium with immediate agreement on y. The equilibrium is supported by “dictatorial threats.” These threats can be dispensed with if X is the unit simplex and the target-vector is Pareto efficient. The results can be modified in a way that allows for arbitrarily long delays in equilibrium. (shrink)

We study a first-price auction preceded by a negotiation stage with complete information, during which bidders may form a bidding ring. We prove that in the absence of externalities, the grand cartel forms in equilibrium, allowing ring members to gain the auctioned object for a minimal price. However, identity-dependent externalities may lead to the formation of small rings, as often observed in practice. Potential ring members may condition their participation on high transfer payments as a compensation for their expected externalities (...) if the ring forms. The cartel may therefore profitably exclude these bidders, although risking tougher competition in the auction. We also analyze ring efficiency in the presence of externalities, showing that a ring may prefer sending an inefficient member to the auction, if the efficient member exerts threatening externalities on bidders outside the ring, which in turn leads to a higher winning price. (shrink)

The main aim of this article is to reconstruct and comment on Bernard Suits’ argument concerning the paradoxicality of the perfectly played game and explain how the argument might contribute to the game vs. performance distinction. The argument was mentioned by Suits in ‘Tricky Triad: Games, Play and Sport’ in the course of argumentation for the distinction between games and performances but it has not been presented in any of Suits’ works published during his lifetime. However, Suits’ fonds (...) deposited in the Special Collections and Archive of the University of Waterloo contains two texts that were nevertheless meant for publication: ‘A Perfectly Played Game’ (recently published as Appendix III to Suits’ Return of the Grasshopper) and unpublished ‘The Search for a Perfectly Fair Game’. The latter is a modified version of the former; there is an overlapping core in both texts, but there are also some essential differences between them. To provide a formula capable of embracing Suits’ ideas from both texts and remove the tension between the ideas of a perfectly played and perfectly fair game, I introduce the concept of a perfect game. (shrink)

The notion of perfect recall in extensive games was introduced by Kuhn (1953), who interpreted it as "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''. We provide a characterization and axiomatization of perfect recall based on two notions of memory: (1) memory of past knowledge and (2) memory of past actions.

This is a chapter written for a popular audience, in which I use poker as a convenient illustration of probability, determinism and counterfactuals. More originally, I also discuss the roles of rationality versus psychological hunches, and explain why even in principle game theory cannot provide us the panacea of a perfect winning srategy. (N.B. The document I have uploaded here is slightly longer than the abbreviated version that appears in the book, and also differs in a few other (...) minor details.) . (shrink)

A syntactic formalism for the modeling of belief revision in perfect information games is presented that allows to define the rationality of a player's choice of moves relative to the beliefs he holds as his respective decision nodes have been reached. In this setting, true common belief in the structure of the game and rationality held before the start of the game does not imply that backward induction will be played. To derive backward induction, a “forward belief” (...) condition is formulated in terms of revised rather than initial beliefs. Alternative notions of rationality as well as the use of knowledge instead of belief are also studied within this framework. Footnotes1 I would like to thank Wlodek Rabinowicz and three anonymous referees for very helpful comments. (shrink)

The logical foundations of game-theoretic solution concepts have so far been explored within the con¯nes of epistemic logic. In this paper we turn to a di®erent branch of modal logic, namely temporal logic, and propose to view the solution of a game as a complete prediction about future play. The branching time framework is extended by adding agents and by de¯ning the notion of prediction. A syntactic characterization of backward induction in terms of the property of internal consistency (...) of prediction is given. (shrink)

The paper provides a framework for representing belief-contravening hypotheses in games of perfect information. The resulting t-extended information structures are used to encode the notion that a player has the disposition to behave rationally at a node. We show that there are models where the condition of all players possessing this disposition at all nodes (under their control) is both a necessary and a sufficient for them to play the backward induction solution in centipede games. To obtain this result, (...) we do not need to assume that rationality is commonly known (as is done in [Aumann (1995)]) or commonly hypothesized by the players (as done in [Samet (1996)]). The proposed model is compared with the account of hypothetical knowledge presented by Samet in [Samet (1996)] and with other possible strategies for extending information structures with conditional propositions. (shrink)

Counterexamples to two results by Stalnaker (Theory and Decision, 1994) are given and a corrected version of one of the two results is proved. Stalnaker's proposed results are: (1) if at the true state of an epistemic model of a perfect information game there is common belief in the rationality of every player and common belief that no player has false beliefs (he calls this joint condition ‘strong rationalizability’), then the true (or actual) strategy profile is path equivalent (...) to a Nash equilibrium; (2) in a normal-form game a strategy profile is strongly rationalizable if and only if it belongs to C8 , the set of profiles that survive the iterative deletion of inferior profiles. (shrink)

For the past 20 years or so the literature on noncooperative games has been centered on the search for an equilibrium concept that expresses the notion of rational behavior in interactive situations. A basic tenet in this literature is that if a “rational solution” exists, it must be a Nash equilibrium. The consensus view, however, is that not all Nash equilibria can be accepted as rational solutions. Consider, for example, the game of Figure 1.

Simple game experiments of the reward allocation, dictator and ultimatum type are used to demonstrate that true explanations of social phenomena cannot conceivably be derived in terms of the perfect rationality concept underlying neo-classical economics. We explore in some depth, if speculatively, how experimental game theory might bring us closer to a new synthesis or at least the nucleus of a general theory of ‘games and boundedly rational economic behavior’ with enhanced explanatory power.

The peculiar features of the climate change problem pose substantial obstacles to our ability to make the hard choices necessary to address it. Climate change involves the convergence of a set of global, intergenerational and theoretical problems. This convergence justifies calling it a 'perfect moral storm'. One consequence of this storm is that, even if the other difficult ethical questions surrounding climate change could be answered, we might still find it difficult to act. For the storm makes us extremely (...) vulnerable to moral corruption. (shrink)

In the last few decades game theory has emerged as a powerful tool for examining a broad range of philosophical issues. It is unsurprising, then, that game theory has been taken up as a tool to examine issues in the philosophy of religion. Economist Steven Brams (1982), (1983) and (2007), for example, has given a game theoretic analysis of belief in God, his main argument first published in this journal and then again in both editions of his (...) book, Superior Beings. I have two main aims in this paper, one specific and one general. My specific aim is to show that Brams’ application of game theory to examine belief in God is, in particular, deeply flawed in two respects. My general aim is to show that any game-theoretic model in which a human being and God are players can only succeed at the cost of abandoning the assumption that God is omnibenevolent. (shrink)

We discuss games of both perfect and imperfect information at two levels of structural detail: players’ local actions, and their global powers for determining outcomes of the game. We propose matching logical languages for both. In particular, at the ‘action level’, imperfect information games naturally model a combined ‘dynamic-epistemic language’ – and we find correspondences between special axioms and particular modes of playing games with their information dynamics. At the ‘outcome level’, we present suitable notions of game (...) equivalence, plus some simple representation results. (shrink)

We present an axiomatic approach for a class of finite, extensive form games of perfect information that makes use of notions like “rationality at a node” and “knowledge at a node.” We distinguish between the game theorist's and the players' own “theory of the game.” The latter is a theory that is sufficient for each player to infer a certain sequence of moves, whereas the former is intended as a justification of such a sequence of moves. While (...) in general the game theorist's theory of the game is not and need not be axiomatized, the players' theory must be an axiomatic one, since we model players as analogous to automatic theorem provers that play the game by inferring (or computing) a sequence of moves. We provide the players with an axiomatic theory sufficient to infer a solution for the game (in our case, the backwards induction equilibrium), and prove its consistency. We then inquire what happens when the theory of the game is augmented with information that a move outside the inferred solution has occurred. We show that a theory that is sufficient for the players to infer a solution and still remains consistent in the face of deviations must be modular. By this we mean that players have distributed knowledge of it. Finally, we show that whenever the theory of the game is group-knowledge (or common knowledge) among the players (i.e., it is the same at each node), a deviation from the solution gives rise to inconsistencies and therefore forces a revision of the theory at later nodes. On the contrary, whenever a theory of the game is modular, a deviation from equilibrium play does not induce a revision of the theory. (shrink)

Game-Theoretic Models of Bargaining provides a comprehensive picture of the new developments in bargaining theory. It especially shows the way the use of axiomatic models has been complemented by the new results derived from strategic models. The papers in this volume are edited versions of those given at a conference on Game Theoretic Models of Bargaining held at the University of Pittsburgh. There are two distinct reasons why the study of bargaining is of fundamental importance in economics. The (...) first is that many aspects of economic activity are directly influenced by bargaining between and among individuals, firms, and nations. The second is that bargaining occupies an important place in economic theory, since the 'pure bargaining problem' is at the opposite pole of economic phenomena from the case of 'perfect competition'. This volume is an outgrowth of the renewed interest in the strategic approach to the theory of bargaining and to the general theory of non-cooperative games. (shrink)

This paper provides a game-theoretic analysis of contrastive focus, extending insights from recent work on the role of noisy communication in prosodic accent placement to account for focus within sentences, sub-sentential phrases and words. The shared insight behind these models is that languages with prosodic focus marking assign prosodic prominence only within elements which constitute material critical for successful interpretation. We first take care to distinguish the information-structural notion of focus from an ontologically distinct notion of givenness marking, and (...) then outline the core properties of focus. We then introduce a signaling game between a speaker and hearer in which the goal is to transmit semantic content with the smallest signal possible. We apply the Iterated Best Response method of Franke to find equilibrium strategies in this game, where a unique equilibrium strategy in this case picks out the “critical information” of an utterance, which by hypothesis constitutes its focus. We show that iterating this game at different syntactic levels of a sentence makes correct predictions about the role of contrast in determining stress within words and phrases, and can be extended to account for association and second occurrence focus effects. (shrink)

We associate with any game G another game, which is a variant of it, and which we call . Winning strategies for have a lower recursive degree than winning strategies for G: if a player has a winning strategy of recursive degree 1 over G, then it has a recursive winning strategy over , and vice versa. Through we can express in algorithmic form, as a recursive winning strategy, many common proofs of non-constructive Mathematics, namely exactly the theorems (...) of the sub-classical logic Limit Computable Mathematics [6], Hayashi and Nakata [7]). (shrink)

According to John Cassian, God bestows his supernatural grace only upon men who transcend Christian legalism and take up Christ’s consilium perfectionis. God’s grace is merited by men who strive to perfection. In so doing, they place themselves sub gratia Christi. For Cassian, the true Christian community is composed solely of ascetics who have set themselves apart from ordinary Christians in order to attain the highest good to which human nature must aspire – theperennial contemplation of God. As Cassian has (...) it, it is the main concern of the ascetic bishop to convey to ordinary Christians the call to perfection. (shrink)

According to John Cassian, God bestows his supernatural grace only upon men who transcend Christian legalism and take up Christ’s consilium perfectionis. God’s grace is merited by men who strive to perfection. In so doing, they place themselves sub gratia Christi. For Cassian, the true Christian community is composed solely of ascetics who have set themselves apart from ordinary Christians in order to attain the highest good to which human nature must aspire – theperennial contemplation of God. As Cassian has (...) it, it is the main concern of the ascetic bishop to convey to ordinary Christians the call to perfection. (shrink)

This is a two-volume set that provides an introduction to non-cooperative Game Theory. Volume 1 covers the basic concepts, while Volume 2 is devoted to advanced topics. The book is richly illustrated with approximately 400 figures. It is suitable for both self-study and as the basis for an undergraduate course in game theory as well as a first-year graduate-level class. It is written to be accessible to anybody with high-school level knowledge of mathematics. At the end of each (...) chapter there is a collection of exercises accompanied by detailed answers. The book contains approximately 180 exercises. (shrink)

‘Game’ means ‘play within the construction of rules’. The sub-category ‘sport’ considers play as competition where the rules are known to the audience, under the following divide: fundamental constructive rules about the game's structure and less important or flexible rules facilitating and monitoring play. These provide athletes and audience with stable knowledge. The excitement of play comes from the vagaries of the actual engagement of the rules in the action of play. The social order can use this as (...) a metaphor of its ideal of civil law in relation to the citizen. (shrink)

Part 1. Introduction -- Introduction: Navigating the Perfect Moral Storm in Light of a Thirty-Five Year Debate -- Thirty-Five Year Climate Change Policy Debate -- Part 2. Priority Ethical Issues -- Ethical Problems with Cost Arguments -- Ethics and Scientific Uncertainty Arguments -- Atmospheric Targets -- Allocating National Emissions Targets -- Climate Change Damages and Adaptation Costs -- Obligations of Sub-national Governments, Organizations, Businesses, and Individuals -- Independent Responsibility to Act -- Part 3. The Crucial Role of Ethics in (...) Climate Change Policy Making -- Why Has Ethics Failed to Achieve Traction? -- Conclusion: Navigating the Perfect Moral Storm. (shrink)

We propose a solution concept for games that are played among players with present-biased preferences that are possibly naive about their own, or about their opponent’s future time inconsistency. Our perception-perfect outcome essentially requires each player to take an action consistent with the subgame perfect equilibrium, given her perceptions concerning future types, and under the assumption that other present and future players have the same perceptions. Applications include a common pool problem and Rubinstein bargaining. When players are naive (...) about their own time inconsistency and sophisticated about their opponent’s, the common pool problem is exacerbated, and Rubinstein bargaining breaks down completely. (shrink)

We study the equilibrium behavior of informed traders interacting with market scoring rule (MSR) market makers. One attractive feature of MSR is that it is myopically incentive compatible: it is optimal for traders to report their true beliefs about the likelihood of an event outcome provided that they ignore the impact of their reports on the profit they might garner from future trades. In this paper, we analyze non-myopic strategies and examine what information structures lead to truthful betting by traders. (...) Specifically, we analyze the behavior of risk-neutral traders with incomplete information playing in a dynamic game. We consider finite-stage and infinite-stage game models. For each model, we study the logarithmic market scoring rule (LMSR) with two different information structures: conditionally independent signals and (unconditionally) independent signals. In the finite-stage model, when signals of traders are independent conditional on the state of the world, truthful betting is a Perfect Bayesian Equilibrium (PBE). Moreover, it is the unique Weak Perfect Bayesian Equilibrium (WPBE) of the game. In contrast, when signals of traders are unconditionally independent, truthful betting is not a WPBE. In the infinite-stage model with unconditionally independent signals, there does not exist an equilibrium in which all information is revealed in a finite amount of time. We propose a simple discounted market scoring rule that reduces the opportunity for bluffing strategies. We show that in any WPBE for.. (shrink)

Personalized and continuing relationships play a central role in any society. Economists have built upon the theories of repeated games and reputations to make important advances in understanding such relationships. Repeated Games and Reputations begins with a careful development of the fundamental concepts in these theories, including the notions of a repeated game, strategy, and equilibrium. Mailath and Samuelson then present the classic folk theorem and reputation results for games of perfect and imperfect public monitoring, with the benefit (...) of the modern analytical tools of decomposability and self-generation. They also present more recent developments, including results beyond folk theorems and recent work in games of private monitoring and alternative approaches to reputations. Repeated Games and Reputations synthesizes and unifies the vast body of work in this area, bringing the reader to the research frontier. Detailed arguments and proofs are given throughout, interwoven with examples, discussions of how the theory is to be used in the study of relationships, and economic applications. The book will be useful to those doing basic research in the theory of repeated games and reputations as well as those using these tools in more applied research. (shrink)

Banach introduced the following two-person, perfect information, infinite game on the real numbers and asked the question: For which sets $A \subseteq \mathbf{R}$ is the game determined????? Rules: The two players alternate moves starting with player I. Each move a n is legal iff it is a real number and $0 , and for $n > 1, a_n . The first player to make an illegal move loses. Otherwise all moves are legal and I wins iff ∑ (...) a n exists and ∑ a n ∈ A. We will look at this game and some variations of it, called Banach games. In each case we attempt to find the relationship between Banach determinancy and the determinancy of other well-known and much-studied games. (shrink)

The stationary set splitting game is a game of perfect information of length ω1 between two players, unsplit and split, in which unsplit chooses stationarily many countable ordinals and split tries to continuously divide them into two stationary pieces. We show that it is possible in ZFC to force a winning strategy for either player, or for neither. This gives a new counterexample to Σ22 maximality with a predicate for the nonstationary ideal on ω1, and an example (...) of a consistently undetermined game of length ω1 with payoff de.nable in the second-order monadic logic of order. We also show that the determinacy of the game is consistent with Martin's Axiom but not Martin's Maximum. (shrink)

The order of stages in a multistage game is often interpreted by looking at earlier stages as involving more long term decisions. For the purpose of making this interpretation precise, the notion of a delay supergame of a bounded multistage game is introduced. A multistage game is bounded if the length of play has an upper bound. A delay supergame is played over many periods. Decisions on all stages are made simultaneously, but with different delays until they (...) become effective. The earlier the stage the longer the delay. A subgame perfect equilibrium of a bounded multistage game generates a subgame perfect equilibrium in every one of its delay supergames. This is the first main conclusion of the paper. A subgame perfect equilibrium set is a set of subgame perfect equilibria all of which yield the same payoffs, not only in the game as a whole, but also in each of its subgames. The second xmain conclusion concerns multistage games with a unique subgame perfect equilibrium set and their delay supergames which are bounded in the sense that the number of periods is finite. If a bounded multistage game has a unique subgame perfect equilibrium set, then the same is true for every one of its bounded delay supergames. Finally the descriptive relevance of multistage game models and their subgame perfect equilibria is discussed in the light of the results obtained. (shrink)

Game-theoretic reasoning pervades economic theory and is used widely in other social and behavioural sciences. An Introduction to Game Theory International Edition, by Martin J. Osborne, presents the main principles of game theory and shows how they can be used to understand economics, social, political, and biological phenomena. The book introduces in an accessible manner the main ideas behind the theory rather than their mathematical expression. All concepts are defined precisely, and logical reasoning is used throughout. The (...) book requires an understanding of basic mathematics but assumes no specific knowledge of economics, political science, or other social or behavioural sciences. Coverage includes the fundamental concepts of strategic games, extensive games with perfect information, and coalitional games; the more advanced subjects of Bayesian games and extensive games with imperfect information; and the topics of repeated games, bargaining theory, evolutionary equilibrium, rationalizability, and maxminimization. The book offers a wide variety of illustrations from the social and behavioural sciences. Each topic features examples that highlight theoretical points and illustrations that demonstrate how the theory may be used. (shrink)

This paper considers undecidability in the imitation game, the so-called Turing Test. In the Turing Test, a human, a machine, and an interrogator are the players of the game. In our model of the Turing Test, the machine and the interrogator are formalized as Turing machines, allowing us to derive several impossibility results concerning the capabilities of the interrogator. The key issue is that the validity of the Turing test is not attributed to the capability of human or (...) machine, but rather to the capability of the interrogator. In particular, it is shown that no Turing machine can be a perfect interrogator. We also discuss meta-imitation game and imitation game with analog interfaces where both the imitator and the interrogator are mimicked by continuous dynamical systems. (shrink)

ABSTRACTBernard Suits and other formalists endorse both the logical incompatibility thesis and the view that rule-breakings resulting in penalties can be a legitimate part of a game. This is what Fred D’Agostino calls ‘the problem of penalties’. In this paper, I reject both Suits’ and D’Agostino’s responses to the problem and argue instead that the solution is to abandon Suits’ view that the constitutive rules of all games are alike. Whereas the logical incompatibility thesis applies to games in which (...) players’ actions are perfectly controlled, it does not apply to sports. This insight not only justifies the rejection of formalism as a theory about the nature of sport but it also helps explain the greater normative complexity of sports, which in turn leads to the idea that in sports ‘cheating’ should be interpreted as a genus. (shrink)

Drawing from narratology and design studies, this article makes use of the notions of the ‘implied designer’ and ‘ludic unreliability’ to understand deceptive game design as a specific sub-set of transgressive game design. More specifically, in this text we present deceptive game design as the deliberate attempt to misguide players’ inferences about the designers’ intentions. Furthermore, we argue that deceptive design should not merely be taken as a set of design choices aimed at misleading players in their (...) efforts to understand the game, but also as decisions devised to give rise to experiential and emotional effects that are in the interest of players. Finally, we propose to introduce a distinction between two varieties of deceptive design approaches based on whether they operate in an overt or a covert fashion in relation to player experience. Our analysis casts light on expressive possibilities that are not customarily part of the dominant paradigm of user-centered design, and can inform game designers in their pursuit of wider and more nuanced creative aspirations. (shrink)

This paper examines the theoretical background and actual behavior in a gaming tournament with endogenous timing where a person has more incentive, structure, and time to form a strategy. The baseline treatment suggests that subgame perfection is a reasonable predictor of behavior –- subjects made 170 of 208 theoretically predicted choices of best actions, with the majority of mistakes made in timing choices by the players who did not survive the cut to the second round. Four sensitivity treatments established that (...) the design feature that lead to more predictable behavior was time to think –- 745 of 960 correctly predicted decisions with more time versus 595 of 960 with less time. A random effects Probit model suggests that the key design feature that closed the gap between predicted and observed behavior was not necessarily the non-linear payoffs created by the tournament design, but rather that the key was providing people with more time to think about their strategy. (shrink)

I introduce an extension of the Lewis-Skyrms signaling game, analysed from a dynamical perspective via simple reinforcement learning. In Lewis’ (Convention, Blackwell, Oxford, 1969) conception of a signaling game, salience is offered as an explanation for how individuals may come to agree upon a linguistic convention. Skyrms (Signals: evolution, learning & information, Oxford University Press, Oxford, 2010a) offers a dynamic explanation of how signaling conventions might arise presupposing no salience whatsoever. The extension of the atomic signaling game (...) examined here—which I will refer to as a salience game—introduces a variable parameter into the atomic signaling game which allows for degrees of salience, thus filling in the continuum between Skyrms’ and Lewis’ models. The model does not presuppose any salience at the outset, but illustrates a process by which accidentally evolved salience is amplified, to the benefit of the players. It is shown that increasing degrees of salience allow populations to avoid sub-optimal pooling equilibria and to coordinate upon conventions more quickly. (shrink)

We develop a logical system that captures two different interpretations of what extensive games model, and we apply this to a long-standing debate in game theory between those who defend the claim that common knowledge of rationality leads to backward induction or subgame perfect (Nash) equilibria and those who reject this claim. We show that a defense of the claim à la Aumann (1995) rests on a conception of extensive game playing as a one-shot event in combination (...) with a principle of rationality that is incompatible with it, while a rejection of the claim à la Reny (1988) assumes a temporally extended, many-moment interpretation of extensive games in combination with implausible belief revision policies. In addition, the logical system provides an original inductive and implicit axiomatization of rationality in extensive games based on relations of dominance rather than the usual direct axiomatization of rationality as maximization of expected utility. (shrink)

In certain finite extensive games with perfect information, Cristina Bicchieri (1989) derives a logical contradiction from the assumptions that players are rational and that they have common knowledge of the theory of the game. She argues that this may account for play outside the Nash equilibrium. She also claims that no inconsistency arises if the players have the minimal beliefs necessary to perform backward induction. We here show that another contradiction can be derived even with minimal beliefs, so (...) there is no paradox of common knowledge specifically. These inconsistencies do not make play outside Nash equilibrium plausible, but rather indicate that the epistemic specification must incorporate a system for belief revision. Whether rationality is common knowledge is not the issue. (shrink)

Bicchieri's topic is the modeling of interaction between decision makers in situations in which the outcome of the interaction depends on what the parties jointly do. Examples include chess, firms competing for business, politicians competing for votes, jury members deciding on a verdict, animals fighting over prey, bidders competing in auctions, threats and punishments in long-term relationships. Rationality assumptions are a basic ingredient of game theory, but though rational choice might be unproblematic in normative decision theory, it becomes problematic (...) in interactive contexts, where the outcome of one’s choice depends on the actions of other agents. Another basic ingredient is the idea of equilibrium play: roughly, an equilibrium is a combination of strategies, one for each player, such that each player’s strategy is a best reply to the other players’ choices. Thus it is individually rational for each agent to play her equilibrium strategy; but, notoriously, such individually rational play can lead to sub-optimal outcomes, as in the well-known prisoner’s dilemma. The relationship between rationality assumptions and equilibrium play is Bicchieri’s main focus. (shrink)

This paper suggests a way of formalizing the amount of information that can be conveyed to each player along every possible play of an extensive game. The information given to each player i when the play of the game reaches node x is expressed as a subset of the set of terminal nodes. Two definitions are put forward, one expressing the minimum amount of information and the other the maximum amount of information that can be conveyed without violating (...) the constraint represented by the information sets. Our definitions provide intuitive characterizations of such notions as perfect recall, perfect information and simultanetty. (shrink)

Backward induction has been the standard method of solving finite extensive-form games with perfect information, notwithstanding the fact that this procedure leads to counter-intuitive results in various games. However, beginning in the late eighties, the method of backward induction became an object of criticism. It is claimed that the assumptions needed for its defence are quite implausible, if not incoherent. It is therefore natural to ask for the justification of backward induction: Can one show that rational players who know (...) the structure of the game, have trust in each other's practical rationality and reason correctly, will act in accordance in backward induction? Several researchers have tried a justification of this kind, but the argument presented in Robert Aumann's paper from 1995 is perhaps the most well-known and influential attempt to provide such a justification. Clausing provides a sustained discussion of the justification problem for backward induction. It is an excellent work and the criticism I will present below does not detract from this evaluation: the issues discussed by the author are complex and it is difficult to get everything right. Furthermore, I hope that the criticism to be presented may be instructive; Even though it has not been Clausing's intention, his logical reconstruction of Aumann's defence of backward induction allows us to see very clearly what is wrong with that argument. It also provides us with * This paper was presented at workshops in Lund and in Uppsala, in the Fall of 1999. I am indebted to the participants for their useful comments. The work on the paper was supported by a generous research grant from The Bank of Sweden Tercentenary Foundation. (shrink)

Despite studies such as Biber, quantitative methodologies remain under-exploited resources in discourse analysis. This study employs a quantitative, statistical approach to re-examine and rethink the rather well-explored topic of register. Using the extensively documented register of Sports Announcer Talk as a case study, careful quantitative analysis exposes the limitations of traditional descriptive approaches to registers. Quantitative analysis reveals significant inter-register variation in the distribution of core SAT features in a television broadcast and a radio broadcast of a basketball game. (...) Further, SAT features appear to function differently in the broadcasts: out of necessity in the radio broadcast and symbolically in the television broadcast. Such inter-register variation of variable frequency and feature function may be a product of differences in communication situation and communicative function related to broadcast media. Quantitative approaches allow more precise defining of registers and provide the researcher insight into the communicative function of discourse features. (shrink)

By adopting Habermas’ communicative theory, this paper categorizes players’ actions into four elements. The strategic action involves players manipulating each other within the framework of a gameFootnote1; normative action is manifested in following the rules and the underlying ethos; dramaturgical action emerges through the players’ deliberate presentation of themselves to both participants and spectators; and communicative action reveals the purpose of a game as a way of being. The conceptualization of game actions leads to a qualitative redefinition of (...) the perfect game, which enables a greater understanding of the game, its participants, and human excellence. As such, this paper’s significance lies in the proposal that the Habermasian perfect game is a potential solution to Suits’ puzzle about what type of games can be played in his Utopia. (shrink)

We consider an infinite two-person game. The second player has a winning perfect information strategy; we show that this player has a winning strategy which depends on substantially less information. The game studied here is a variation on a game of Gale.

We examined how language supports the expression of temporality within sentence boundaries in English, which has a rich inventory of grammatical means to express temporality. Using a computational model that mimics how humans learn from exposure we explored what the use of different tense and aspect combinations reveals about the interaction between our experience of time and the cognitive demands that talking about time puts on the language user. Our model was trained on n-grams extracted from the BNC to select (...) the TA combination that fits the context best. It revealed the existence of two different sub-systems within the set of TA combinations, a “simplex” one that is supported lexically and is easy to learn, and a “complex” one that is supported contextually and is hard to learn. The finding that some TA combinations are essentially lexical in nature necessitates a rethink of tense and aspect as grammatical categories that form the axes of the temporal system. We argue that the system of temporal reference may be more fruitfully thought of as the result of learning a system that is steeped in experience and organised along a number of functional principles. (shrink)

The Mirror Game (MG) is a common exercise in dance/movement therapy and drama therapy. It is used to promote participants’ ability to enter and remain in a state of togetherness. In spite of the wide use of the MG by practitioners, it is only recently that scientists begun to use the MG in research, examining its correlates, validity and reliability. This study joins this effort by reporting on the identification of scale items to describe the nonverbal behaviour expressed during (...) the MG and its correlation to measures of attachment. Thus, we explored the application of the MG as a tool for assessing the embodiment of attachment in adulthood. Forty-eight participants (22 females, mean age = 33.2) played the MG with the same gender-matched expert players. All MG were videotaped. In addition, participants were evaluated on two central measurements of attachment in adulthood: The Adult Attachment Interview (AAI) and the Experience in Close Relationship questionnaire (ECR). To analyse the data, we developed the “mirror game scale” that coded the nonverbal behavior during the movement interaction, using 19 parameters. The sub-scales were reduced using factor analysis into two dimensions referred to as “together” and “free”. The free factor was significantly correlated to both measurements of attachment: Participants classified as having secure attachment on the AAI, received higher scores on the MG free factor than participants classified as insecure (t (46) = 7.858, p =.000). Participants who were high on the avoidance dimension on the ECR, were low on the MG free factor (r (48) =-.-285, p =.007). This is the first study to examine the MG as it is used by practitioners and its correlation to highly standardized measures. This exploratory study may be considered as part of the first steps of exploring the MG as a standardized assessment tool. The advantages of the MG as a simple, non-verbal movement interaction demonstrate some of the strengths of dance/movement and drama therapy practice. (shrink)