Isomorphism of Intransitive Linear Lie Equations

We show that formal isomorphism of intransitive linear Lie equations along transversal to the orbits can be extended to neighborhoods of these transversal. In analytic cases, the word formal is dropped from theorems. Also, we associate an intransitive Lie algebra with each intransitive linear Lie equation, and from the intransitive Lie algebra we recover the linear Lie equation, unless of formal isomorphism. The intransitive Lie algebra gives the structure functions introduced by E. Cartan

The Analysis of Seasonal Return Anomalies in the Portuguese Stock Market

This paper assesses the existence of persistent seasonal effects in the daily returns of the Portuguese stock market. We use daily data on the stock market index to study long-lasting differences in returns across the days of the week, within months and around holidays. For the period 1988-2001, we find no evidence that daily returns are different between weekdays. However, we find a closed-market effect during 1988-1996. This effect disappears for the 1997-2001 period which coincides with the period from when the Portuguese market started to be internationally considered as a developed market.

Mass media and repulsive interactions in continuous-opinion dynamics

This letter focus on the effect of repulsive interactions on the adoption of an external message in an opinion model. With a simple change in the rules, we modify the Deffuant \emph{et al.} model to incorporate the presence of repulsive interactions. We will show that information receptiveness is optimal for an intermediate fraction of repulsive links. Using the master equation as well as Monte Carlo simulations of the message-free model, we identify the point where the system becomes optimally permeable to external influence with an order-disorder transition

Market Impact of International Sporting and Cultural Events

This paper investigates the impact of international sporting and cultural events on national stock markets. We study market reaction to the announcements of the selected country hosting mega-events such as the Olympic Games, the World and the European Football Cups and World Exhibitions. First, we evaluate the abnormal returns of winning bidders at (and around) the announcement date at market and industry-levels. Second, we analyze the determinants of the variation in abnormal returns across events and industries and control for the prior probability of observing the event. Third, on the basis of a simple model of partial anticipation, we reexamine the abnormal returns observed for the winning and losing countries. Our initial results suggest that the abnormal returns are not consistently different from zero. Further, when we look at particular industries, we find no evidence supporting that industries, that a priori were more likely to extract direct benefits from the event, observe positive significant effects. Yet when we control for the prior expectations, the announcement of these megaevents is associated with a positive stock market reaction in the nominated country and a negative reaction in the losing country. Overall we interpret our findings as supportive of rational asset pricing and partial anticipation.Market efficiency; Event studies; Mega-events

Market Impact of International Sporting and Cultural Events

This paper investigates the impact of international sporting and cultural events on national stock markets. We study market reaction to the announcements of the selected country hosting the Summer and Winter Olympic Games, the World Football Cup, the European Football Cup and World and Specialized Exhibitions. We also measure the market effects of the announcement of the nomination of the European Cultural City. First, we evaluate the abnormal returns of winning bidders at (and around) the announcement date using an event study methodology. We study the impact at market and industry-levels. Second, we analyze the determinants of the variation in abnormal returns across events and industries on the basis of a set of variables found important by previous studies and control for the prior probability of observing the event. Third, on the basis of a simple model of partial anticipation, we reexamine the abnormal returns observed for the winning and losing countries and perform a series of tests to disentangle the different theoretical arguments that could account for the observed stock market behavior. Our initial results suggest that the abnormal returns measured at the announcement date and around the event are not consistently different from zero. Further, when we look at particular industries, we find no evidence supporting that industries, that a priori were more likely to extract direct benefits from the event, observe positive significant effects. Yet when we control for the prior expectations, the announcement of these mega-events is associated with a positive market reaction in the nominated country and a negative reaction in the losing country. Overall we interpret our findings as supportive of rational asset pricing and partial anticipation.Market efficiency; Event studies; Mega-events

A guerra esquiva.O conflito luso-castelhano de 1336-1338

A exemplo do que acontece com a maior parte dos conflitos militares anteriores ao reinado de D. Fernando, também a guerra que opôs, entre 1336 e 1338, os reinos de Portugal e de Castela continua por estudar, conhecendo-se apenas e em traços muito gerais alguns dos seus principais episódios1. Apesar da importância política e militar de que se reveste, muito pouco tem sido escrito sobre o tema2, facto que se por um lado se deve à falta de interesse pela História Militar deste período, por outro, deriva também da pouca atenção que tem sido dedicada aos 35 anos de reinado de D. Afonso IV