The non-existence of a universal topological type space

The concept of types was introduced by Harsányi[8]. In the literature there are two approaches for formalizing types, type spaces: the purely measurable and the topological models. In the former framework Heifetz and Samet [11] showed that the universal type space exists and later Meier[13] proved that it is complete. In this paper we examine the topological approach and conclude that there is no universal topological type space in the category of topological type spaces

Adoption and Aspiration: The Uniform Adoption Act, the Deboer-Schmidt Case, and the American Quest for the Ideal Family

When the state must designate a child\u27s legal parentage, should the goal be to protect the biological parents\u27 opportunity interests to raise their child or to protect the child\u27s established relationships with the individuals who have actually functioned as her parents? What characteristics render an adult an appropriate parent? These questions, long in the background of disputes over adoption, have been raised with new intensity in the early 1990s in two distinctive settings. The first is the debate about these questions waged in the courts and the media. The second is the effort of the National Conference of Commissioners on Uniform State Laws (NCCUSL) to create a Uniform Adoption Act. The fate of the child called Jessica by her would-be adopters in Michigan and Anna by her birth parents in Iowa was a matter of agitated public debate before, during, and after it was decided by a legal system slow to resolve the conflicting claims of the adoptive and birth parents and even slower to recognize the young child\u27s interest in a quick decision. 1 Similarly, the law\u27s inability to resolve the competing claims of entitlement with respect to other young children--Richard Doe in Illinois, Emily W. in Florida, Michael S. in California--generates yet more media attention to the questions of where do children belong? and to whom do children belong? 2 As American culture\u27s internal conflicts over the ideal family are projected onto the various individuals, relationships, and households involved in each case, images of the conflicting ..

On the Evolutionary Emergence of Optimism

Successful individuals were frequently found to be overly optimistic. This is puzzling because it might be thought that optimistic individuals who consistently overestimate their eventual payoffs will not do as well as realists who see the situation as it truly is and hence will not survive evolutionary pressures. We show that contrary to this intuition, there is a large class of either competitive or cooperative strategic interactions between randomly matched pairs of individuals in the population, in which "cautiously" optimistic individuals not only survive but also prosper and take over the entire population. The reason for this result is that optimistic individuals who overestimate the impact of their actions on their payoffs, behave more aggressively than realists and pessimists. When the interactions between individuals involve negative externalities (the payoff of one player decreases with the actions taken by another player) and the actions are strategic substitutes, being aggressive induces the opponent to be softer, so optimists gain a strategic advantage that, for moderate levels of optimism, outweighs the loss from having the wrong perception of the environment. Likewise, when the interactions between individuals involve positive externalities and the actions are strategic complements, being aggressive triggers a favorable aggressive behavior from the opponent. Hence, in both cases, cautiously optimistic types fare better on average than other types of individuals. We show that if the initial distribution of types is sufficiently wide, then over time it will converge in distribution to a mass point on some level of cautious optimism.

Derivation of the Local-Mean Stochastic Quantum Force

We regard the non-relativistic Schrodinger equation as an ensemble mean representation of the stochastic motion of a single particle in a vacuum, subject to an undefined stochastic quantum force. The local mean of the quantum force is found to be proportional to the third spatial derivative of the probability density function, while its associated pressure is proportional to the second spatial derivative. The latter arises from the single particle diluted gas pressure, and this observation allows to interpret the quantum Bohm potential as the energy required to put a particle in a bath of fluctuating vacuum at constant entropy and volume. The stochastic force expectation value is zero and is uncorrelated with the particle location, thus does not perform work on average. Nonetheless it is anti-correlated with volume and this anti-correlation leads to an uncertainty relation. We analyze the dynamic Gaussian solution to the Schrodinger equation as a simple example for exploring the mean properties of this quantum force. We conclude with a few possible interpretations as to the origins of quantum stochasticity.Comment: Accepted to Fluctuation and Noise Letters. This manuscript supersedes arXiv:1607.0284

Common Knowledge of Rationality and Market Clearing in Economies with Asymmetric Information

Consider an exchange economy with asymmetric information. What is the set of outcomes that are consistent with common knowledge of rationality and market clearing? To address this question we define an epistemic model for the economy that provides a complete description not only of the beliefs of each agent on the relationship between states of nature and prices but also of the whole system of interactive beliefs. The main result, theorem 1, provides a characterization of outcomes that are consistent with common knowledge of rationality and market clearing (henceforth, CKRMC outcomes) in terms of a solution notion - Ex - Post Rationalizability - that is defined directly in terms of the parameters that define the economy. We then apply theorem 1 to characterize the set of CKRMC outcomes in a general class of economies with two commodities. CKRMC manifests several intuitive properties that stand in contrast to the full revelation property of Rational Expectations Equilibrium: In particular, we obtain that for a robust class of economies: (1) there is a continuum of prices that are consistent with CKRMC in every state of nature, and hence these prices do not reveal the true state, (2) the range of CKRMC outcomes is monotonically decreasing as agents become more informed about the economic fundamentals, and (3) trade is consistent with common knowledge of rationality and market clearing even when there is common knowledge that there are no mutual gains from trade.common knowledge, rationality, rationalizability, rationalizable expectations

Unawareness, Beliefs and Games

We define a generalized state-space model with interactive unawareness and probabilistic beliefs. Such models are desirable for many potential applications of asymmetric unawareness. We develop Bayesian games with unawareness, define equilibrium, and prove existence. We show how equilibria are extended naturally from lower to higher awareness levels and restricted from higher to lower awareness levels. We use our unawareness belief structure to show that the common prior assumption is too weak to rule out speculative trade in all states. Yet, we prove a generalized “No-trade” theorem according to which there can not be common certainty of strict preference to trade. Moreover, we show a generalization of the “No-agreeing-to-disagree” theorem