Existence and uniqueness of a fixed-point for local contractions

This paper proves the existence and uniqueness of a fixed-point for local contractions without assuming the family of contraction coefficients to be uniformly bounded away from 1. More importantly it shows how this fixed-point result can apply to study existence and uniqueness of solutions to some recursive equations that arise in economic dynamics.

Avaliação dos aspectos subjetivos nos projetos de arquitetura dos alunos de planejamento

Com a intenção de melhor serem conhecidas as formas de avaliação daquilo que chamamos "aspectos subjetivos", nos projetos de arquitetura, selecionamos e entrevistamos 7 arquitetos, escolhidos por suas atuações, tanto profissionais como no magistério. Apresentamos, inicialmente, algumas das mais importantes posições teóricas sobre avaliação, procurando-se, também, mostrar o enfoque sociológico do assunto. Desde logo observamos pontos de vista diversos, divergentes e até discrepantes, entre os vários autores selecionados, o que nos alertou para um possivel ingresso em terreno polêmico. Como metodologia de trabalho, procuramos entrevistar os professores, usando-se as mesmas condições para todos eles (ambiente calmo, descontraído, sem pressa e sem interrupções), ocasião em que um elenco de perguntas era proposto. As respostas foram registradas em um gravador, que ficava à vista, sobre a mesa. Garantimos aos entrevistados que não haveria identificação da autoria das declarações, propiciando-se, assim, mais "fluência" nas respostas e, talvez, um pouco mais de "ousadia" nas afirmações. Em seguida, e já a partir das diversas declarações, buscamos destacar a visão de avaliação de cada um, para em seguida, afunilar essa análise, focalizando, mais especificamente, os aspectos objetivos e os subjetivos na avaliação dos projetos de arquitetura. Concluimos que, apesar das muitas maneiras de avaliar, e de até não avaliar os trabalhos de projeto, há várias atitudes, sistemas, métodos, etc - alguns até conflitantes - empregados pelos diversos professores, que formam, entretanto, uma base comum, uma postura semelhante, entre eles. Essa identidade provém da constatação de que houve unanimidade, entre os entrevistados, de ser a arte uma resultante da composição de ingredientes culturais e ideológicos, provenientes, principalmente, das condições materiais, num determinado momento histórico. Na Arquitetura, com maior ênfase ainda, por ser uma arte utilitária, o seu "engajamento ideológico" torna-se inevitável e, consequentemente a sua avaliação, de forma jacente ou subjacente, será feita por essa ótica.

Using common features to understand the behavior of metal-commodity prices and forecast them at different horizons

The objective of this article is to study (understand and forecast) spot metal price levels and changes at monthly, quarterly, and annual horizons. The data to be used consists of metal-commodity prices in a monthly frequency from 1957 to 2012 from the International Financial Statistics of the IMF on individual metal series. We will also employ the (relatively large) list of co-variates used in Welch and Goyal (2008) and in Hong and Yogo (2009) , which are available for download. Regarding short- and long-run comovement, we will apply the techniques and the tests proposed in the common-feature literature to build parsimonious VARs, which possibly entail quasi-structural relationships between different commodity prices and/or between a given commodity price and its potential demand determinants. These parsimonious VARs will be later used as forecasting models to be combined to yield metal-commodity prices optimal forecasts. Regarding out-of-sample forecasts, we will use a variety of models (linear and non-linear, single equation and multivariate) and a variety of co-variates to forecast the returns and prices of metal commodities. With the forecasts of a large number of models (N large) and a large number of time periods (T large), we will apply the techniques put forth by the common-feature literature on forecast combinations. The main contribution of this paper is to understand the short-run dynamics of metal prices. We show theoretically that there must be a positive correlation between metal-price variation and industrial-production variation if metal supply is held fixed in the short run when demand is optimally chosen taking into account optimal production for the industrial sector. This is simply a consequence of the derived-demand model for cost-minimizing firms. Our empirical evidence fully supports this theoretical result, with overwhelming evidence that cycles in metal prices are synchronized with those in industrial production. This evidence is stronger regarding the global economy but holds as well for the U.S. economy to a lesser degree. Regarding forecasting, we show that models incorporating (short-run) commoncycle restrictions perform better than unrestricted models, with an important role for industrial production as a predictor for metal-price variation. Still, in most cases, forecast combination techniques outperform individual models.

Using common features to understand the behavior of metal-commodity prices and forecast them at different horizons

The objective of this article is to study (understand and forecast) spot metal price levels and changes at monthly, quarterly, and annual frequencies. Data consists of metal-commodity prices at a monthly and quarterly frequencies from 1957 to 2012, extracted from the IFS, and annual data, provided from 1900-2010 by the U.S. Geological Survey (USGS). We also employ the (relatively large) list of co-variates used in Welch and Goyal (2008) and in Hong and Yogo (2009). We investigate short- and long-run comovement by applying the techniques and the tests proposed in the common-feature literature. One of the main contributions of this paper is to understand the short-run dynamics of metal prices. We show theoretically that there must be a positive correlation between metal-price variation and industrial-production variation if metal supply is held fixed in the short run when demand is optimally chosen taking into account optimal production for the industrial sector. This is simply a consequence of the derived-demand model for cost-minimizing firms. Our empirical evidence fully supports this theoretical result, with overwhelming evidence that cycles in metal prices are synchronized with those in industrial production. This evidence is stronger regarding the global economy but holds as well for the U.S. economy to a lesser degree. Regarding out-of-sample forecasts, our main contribution is to show the benefits of forecast-combination techniques, which outperform individual-model forecasts - including the random-walk model. We use a variety of models (linear and non-linear, single equation and multivariate) and a variety of co-variates and functional forms to forecast the returns and prices of metal commodities. Using a large number of models (N large) and a large number of time periods (T large), we apply the techniques put forth by the common-feature literature on forecast combinations. Empirically, we show that models incorporating (short-run) common-cycle restrictions perform better than unrestricted models, with an important role for industrial production as a predictor for metal-price variation.

The performance of open-end Brazilian fixed income mutual funds for retail clients

From a financial perspective, this dissertation analyzes the Brazilian mutual fund industry performance for an average retail client. The most representative funds for the local population, that are the fixed income open-end ones, will be selected and their performance will be measured aiming to answer if clients of this industry obtained a proper return over their investments in the period between August 2010 and August 2013. A proper return will be understood as the preservation of the purchasing power of the individual´s savings, what is achieved with a positive performance of a mutual fund after discounting taxes, administrative fees and inflation. After obtaining an answer for the previous question, this dissertation will explore a possible alternative solution: Tesouro Direto, that is an example of a financial approach that could foster the disintermediation between savings and investments through electronic channels. New electronic platforms, with a broader scope, could be utilized to increase the efficiency of funding productive investments through better remunerating Brazilian savings. Tesouro Direto may point towards a new paradigm.