Agreeing to disagree in a countable space of equiprobable states

An example is given in which agents agree to disagree, showing that Aumann's (1976) Agreement Theorem does not extend to a countable space of equiprobable states of nature. Even in this unorthodox setting, if the sets of the information partitions are intervals, an agreement theorem holds. A result that describes the margin for disagreement is also obtained.Agreeing to disagree, Interactive epistemology, Bounded rationality.

Do estado da arte às grandes questões

Esta investigação tem como objetivo sintetizar o estado do conhecimento e gerar novas perspetivas orientadas para o papel de Portugal na arquitetura de segurança da África Austral no período compreendido entre 1945 e 1975, no qual acreditamos que, ao resistir à descolonização e ao adotar uma estratégia de aproximação à África do Sul e à Rodésia no início da década de 1960, Portugal foi determinante para a globalização da Guerra Fria. Recorrendo a uma abordagem dedutiva, concluímos que existiu uma arquitetura de segurança na forma de complexo, com dois períodos distintos (1945-1960 e 1960-1975), e que a estratégia portuguesa uniu o Atlântico-Norte ao Atlântico-Sul ao cooptar os EUA para a defesa do “reduto branco”. A investigação gerou novas questões centradas nas consequências securitárias resultantes do fim da presença portuguesa na África Austral, e também na clarificação do papel securitário de outros atores no período 1945-1975. Abstract: This research aims to synthesize the state of knowledge and generate new perspectives towards the role of Portugal in the Southern African security architecture between 1945 and 1975, in which we believe that, by resisting to decolonization and adopting an approaching strategy to South Africa and Rhodesia at the beginning of 1960 decade, Portugal was decisive for the globalization of the Cold War. By using a deductive approach one concludes that there was a security architecture in the form of complex with two distinguished periods (1945-1960 and 1960-1975), and that portuguese strategy joined the South and North-Atlantic by co-opting the USA to the defense of the "white redoubt". The research generated new questions centered on the security consequences resulting from the portuguese exit from Southern Africa, and also on clarification of other actors’ security role on 1945-1975 period

Past expectations as a determinant of equilibrium prices - hysteresis in a simple economy

We give an illustration of hysteresis (path-dependence) in a simple economy. In the presence of multiple possible equilibrium prices, we find that past expectations determine present prices. This phenomenon of path-dependence is robust under perturbations of the economy.Hysteresis, Path-dependence, Tatônnement, Equilibrium selection

Free daily newspapers: too many incentives to print?

We consider a model in which a free daily newspaper distributes news to readers and sells ad-space to advertisers, having private information about its readership. Depending on the type of readers in the market, the newspaper's may have a "plentiful and seeking" audience or a "lacking and avoiding" audience. We find that if the readers are plentiful and seeking, the newspaper prints an excessive number of copies. The rationale for this over-printing strategy lies on the newspaper's need to send a credible signal to the advertisers that there are plentiful and seeking readers in the market. When the readers are lacking and avoiding, the newspaper chooses the socially optimal tirage (does not try to cheat the advertisers).two-sided markets, asymmetric information, free press

Agreeing to Disagree with Multiple Priors

We present an extension of Aumann's Agreement Theorem to the case of multiple priors. If agents update all their priors, then, for the Agreement Theorem to hold, it is sufficient to assume that they have closed, connected and intersecting sets of priors. On the other hand, if agents select the priors to be updated according to the maximum likelihood criterion, then, under these same assumptions, agents may still agree to disagree. For the Agreement Theorem to hold, it is also necessary to assume that the maximum likelihood priors are commonly known and not disjoint. To show that these hypotheses are necessary, we give several examples in which agents agree to disagree.Agreeing to disagree, multiple priors, Aumann's Agreement Theorem

Costly horizontal differentiation

We study the effect of quadratic differentiation costs in the Hotelling model of endogenous product differentiation. The equilibrium location choices are found to depend on the magnitude of the differentiation costs (relatively to the transportation costs supported by consumers). When the differentiation costs are low, there is maximum differentiation. When they are intermediate, there is partial differentiation, with a degree of differentiation that decreases with the differentiation costs. When they are above a certain threshold, there is no equilibrium. In any case, the socially optimal degree of differentiation is always lower than the equilibrium level. We also study the case of collusion between firms. If firms can combine locations but not prices, they locate asymmetrically when differentiation costs are high and choose maximum differentiation when they are low. When collusion extends to price setting, there is partial differentiation.Costly product differentiation, Spatial competition, Hotelling model

Detailed design of a class I UAV for maritime surveillance

ALFAL/ENGAER 138081-J João Correia. Examination Committee: Chairperson: MGEN/ENGAER 076441-J Paulo Manuel Veloso Gonçalves Guerra (DMSA); Supervisor: MAJ/ENGAER 129905-A Luís Filipe da Silva Félix (AFA); Supervisor: CAP/ENGAER 131603-G João Vítor Aguiar Vieira Caetano (AFA); Member of the Committee: Doutor Frederico José Prata Rente Reis Afonso (IST)Esta tese destina-se ao design estrutural em materiais compósitos de um Veículo Aéreo Não-Tripulado (VANT) de classe I para vigilância marítima. A intenção de expandir o uso de VANTs pela Força Aérea Portuguesa (FAP), na ampla área de jurisdição portuguesa e nas operações internacionais, motivou a necessidade de desenvolver uma nova plataforma capaz de cumprir todos os requisitos operacionais e tecnológicos. A presente tese começa pela definição dos sistemas a bordo necessários para a aeronave, nomeadamente a carga útil, aviónicos e propulsão. O design estrutural ao nível conceptual e preliminar envolveu o planeamento da disposição geral da aeronave para atingir uma margem estática longitudinal válida e a determinação do envelope de voo com rajada para determinar o factor de carga da aeronave. Este parâmetro vai definir a caracterização das forças aerodinâmicas e inérciais para a manobra crítica de voo. O projecto detalhado da aeronave foi realizado através de modelação em Desenho Assistido por Computador (CAD) com o objetivo de minimizer o peso estrutural. O design foi confirmado por uma análise numérica de tensões através de uma Análise de Elementos Finitos (FEA) e foi alcançada convergência para os valores obtidos de tensão e de deslocamento. O design desenvolvido é capaz de suportar a condição de carga crítica sem falha estrutural. A configuração da aeronave com todos os sistemas a bordo apresenta um peso dentro dos limites para a respectiva classe e uma autonomia de oito horas para operações de vigilância marítima. O design desenvolvido pode apresentar outras configurações, e tem uma autonomia máxima de doze horas.This thesis concerns the composite structural design of a class I Unmanned Aerial Vehicle (UAV) for maritime surveillance. The intention to expand the UAV use by Portuguese Air Force (FAP), over the broad area of Portuguese jurisdiction and in international operations, motivated the need to develop a new platform capable to fulfil all the operational and technological requirements. This thesis starts by defining all the necessary onboard systems for the aircraft, namely the payload, avionics and propulsion. The conceptual and preliminary structural design involved planning the general layout to achieve a valid longitudinal static margin and determining the aircraft flight envelope with gust loads to determine the design load. This design driver set the aerodynamic and inertial load characterization of the critical flight manoeuvre. The aircraft detailed design was performed through Computed Aided Design (CAD) modelling with the objective of minimizing the structural weight. The design was endorsed by a numerical stress analysis through a Finite Element Analysis (FEA) and achieved convergence for the stress and displacement results. The developed design withstands the critical load condition without failure of the structure. The aircraft configuration with full payload presents a weight within its class range and an endurance of eight hours for maritime surveillance operations. The implemented design supports other configurations, presenting an endurance up to twelve hours.N/

Three-State Complex Valued Spins Coupled to Binary Branched Polymers in Two-Dimensional Quantum Gravity

A model of complex spins (corresponding to a non-minimal model in the language of CFT) coupled to the binary branched polymer sector of quantum gravity is considered. We show that this leads to new behaviour.Comment: 3 pages, Latex2e, 2 eps figures, uses espcrc2 and epsf. Contribution to LATTICE 97, to appear in the Proceeding