192 research outputs found
Interactive and common knowledge in the state-space model
No full textThis paper deals with the prevailing formal model for knowledge in contemporary economics, namely the state-space model introduced by Robert Aumann in 1976. In particular, the paper addresses the following question arising in this formalism: in order to state that an event is interactively or commonly known among a group of agents, do we need to assume that each of them knows how the information is imparted to the others? Aumann answered in the negative, but his arguments apply only to canonical, i.e., completely specified state spaces, while in most applications the state space is not canonical. This paper addresses the same question along original lines, demonstrating that the answer is negative for both canonical and not-canonical state spaces. Further, it shows that this result ensues from two counterintuitive properties held by knowledge in the state-space model, namely Substitutivity and Monotonicity.
Information Structures with Unawareness
No full textI construct a state space model with unawareness following Aumann (1976). Dekel, Lipman and Rustichini (1998a) show that standard state space models are incapable of representing unawareness. The model circumvents the impossibility result by endowing the agent with a subjective state space that differs from the full state space when he has the unawareness problem. Information is modeled as a pair, consisting of both factual information and awareness information. The model preserves the central properties of the standard information partition model.unawareness, information, information partition, state space models
False Consciousness in Financial Markets: Or is it in Ivory Towers?
No full textIn general, models in finance assume that investors are risk averse. An example of such a recent model is the pioneering work of Aumann and Serrano, which presents an economic index of riskiness of gambles which is independent of wealth and holds (as might be understood from the adjective “economic”) for exclusively risk averse investors. In their paper, they discuss gambles with positive expected returns which will be accepted or rejected by agents which different levels of risk aversion. The question never asked by the authors (and in most of the finance literature) is: Who is offering these attractive gambles? To arrive at an answer, we extend the Aumann-Serrano risk index in such a way that it accommodates gambles with either positive or negative expectations and is thus suitable for both the risk averse and risk lovers. Once we allow for the existence of risk lovers, it may be shown that in financial markets, many gambles with negative expectations are taken either knowingly or unknowingly so that there are always people that act as if they are risk lovers. The paper concludes with a brief discussion of the implications of our result, in particular that gambling is by no means restricted to the casino or the track.
Symphonies - Don Mus.Ms. 147 : strings, brasses; D; DorA 20.25
No full textJoseph Anton Xaver AuffmannWeiterer zitierter Komponist: Franz Josef Aumann. - Quelle: manuscript. - Provenienz: Fürstlich Fürstenbergische Hofbibliothek, DonaueschingenConcerto Ex. d. | â | Violino Primo | Violino Secundo | Alto Viola | Cornu Prima | Cornu Secundo | Cum Basso | Auth. del. Sign. Auffma
Late Breaking Abstract - Carnosine and related compounds in m. vastus lateralis of COPD patients: preliminary results
No full textAgreeing to agree
No full textAumann has shown that agents who have a common prior cannot have common knowledge of their posteriors for event if these posteriors do not coincide. But given an event , can the agents have posteriors with a common prior such that it is common knowledge that the posteriors for \emph{do} coincide? We show that a necessary and sufficient condition for this is the existence of a nonempty \emph{finite} event with the following two properties. First, it is common knowledge at that the agents cannot tell whether or not occurred. Second, this still holds true at , when itself becomes common knowledge.Agreeing theorem, common knowledge, common prior, no trade theorem
When All is Said and Done, How Should You Play and What Should You Expect?
No full textModern game theory was born in 1928, when John von Neumann published his Minimax Theorem. This theorem ascribes to all two-person zero-sum games a value–what rational players may expect–and optimal strategies–how they should play to achieve that expectation. Seventyseven years later, strategic game theory has not gotten beyond that initial point, insofar as the basic questions of value and optimal strategies are concerned. Equilibrium theories do not tell players how to play and what to expect; even when there is a unique Nash equilibrium, it it is not at all clear that the players “should” play this equilibrium, nor that they should expect its payoff. Here, we return to square one: abandon all ideas of equilibrium and simply ask, how should rational players play, and what should they expect. We provide answers to both questions, for all n-person games in strategic form.
Analyses of the "Gans" Committee Report
No full textThis document contains four separate analyses, each with a different author, of the "Gans" committee report on the Bible codes (DP 364 of the Center for the Study of Rationality, June 2004). The analyses appear in alphabetical order of the authors' names. Three of the authors were members of the committee; one, Doron Witztum, is active in Bible codes research. Two of the analyses-by Aumann and by Furstenberg-support the report of the committee; the other two-by Lapides and by Witztum-do not. This document contains material that was generated after the results of the committee's experiments became known; other than reporting the numerical results themselves, DP 364 contains only material generated before they became known.
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