Dynamic models in disequilibrium theory

The thesis offers various contributions to the formulation of dynamical disequilibrium models in economic theory. Until now static disequilibrium situations have usually been analyzed by assuming prices fixed so that equilibrium is obtained only by quantity adjustments. We consider in this work dynamical models, where the evolution of a rationed equilibrium economy through time is described by varations in both prices and quantities. Using Malinvaud's static macromodel as the starting point, we introduce in Chapter I a simple dynamization by requiring quantities to adjust infinitely fast to the equilibrium values. This implies that the evolution of the economy is determined by the evolution in prices. Explicit differential equations for the changes in prices are formulated, and a global stability theorem for the Walrasian (no rationing at all) equilibrium is obtained by assuming a specific behaviour on the boundary between the regions of Repressed inflation and Keynesian equilibrium. In Chapter II the model is changed by supposing quantities to adjust quickly, though not instantaneously, compared with prices. Assuming the differential equation describing the fast adjustment in quantities to depend smoothly on prices, we show that equilibria exhibit "exchange of stability" whenever the prices cross the boundary between two equilibrium regions in the parameter plane. Using methods from catastrophe theory a generic description of the long term evolution is obtained by introducing new "dual" equilibria in the quantity space and increasing the dimension of the parameter space by introducing parameters, which are usually "hidden" in the standard description. Chapter III is devoted to an extension of this result to a situation, where consumers may gain by saving money from one period to the next, a case excluded in Chapter II by an assumption on the consumer's money holdings being unchanged from period to period. The result is obtained by dividing the consumers into unemployed, spending the same fixed amount of unemployment benefit every period, and employed consumers, who are allowed to save. The results of changes in either the unemployment benefit or the government's demand are also considered. Finally Chapter IV is devoted to a specific analysis of the long term evolution in the neighbourhood of the Repressed inflation - Keynesian boundary. This analysis is necessary because of a discontinuity of the vector field describing the adjustments in prices on this boundary. Introducing timelags in agents' response to changes in prices we show how the discontinuous vector field gives rise to a smooth evolution around this boundary. Further, depending on the distribution of timelags, the economy exhibits either decreasing oscillations around the boundary eventually converging to zero, or (semi-)stable steady oscillations between the two regions. In this way the results contribute to a clarification of the claim that a basic feature of modem economies is the cycling motion between Repressed inflation and Keynesian equilibria

Rubenstein's Solution of the Bargaining Problem: Some Generalisations and Extensions

Tese de mestrado em Linguística apresentada à Faculdade de Letras da Universidade de CoimbraAs sequências textuais explicativas e argumentativas configuram-se as dominantes em diversos géneros textuais que ocupam um primeiro plano no recente Programa e Metas de Português do ensino secundário. Por nos parecer que é possível partir das sequências textuais básicas para abordar, depois, alguns géneros textuais distintos (não constituindo, no entanto, nosso objetivo a problematização dessas relações) e que, sendo pertinente na nossa área profissional, não tem sido alvo de grande atenção, elegemos como tópico de trabalho a dimensão enunciativa das sequências textuais explicativa e argumentativa. O nosso objetivo é contribuir para a realização de um trabalho pedagogicamente mais apurado em torno das sequências textuais, uma vez que um maior conhecimento das estruturas textuais e da sua organização permitirá aos alunos reconhecê-las e usá-las em diferentes géneros textuais. Para dar consecução aos nossos objetivos, baseámo-nos, principalmente, nos trabalhos de Adam sobre as sequências textuais; para a enunciação e dêixis recorremos aos estudos de Benveniste e Kerbrat-Orecchioni, enquanto o tratamento da polifonia linguística foi fundamentado pelos estudos de Ducrot e pela investigação de Vion e Fløttum. Ao ampliar o âmbito da noção de ‘pessoa’ de Benveniste com a introdução da categoria do ‘ponto de vista’, complementou-se a noção de subjetividade e intersubjetividade. O corpus que sustentou o estudo foi recolhido com base em produções de sequências textuais explicativas e argumentativas, produzidas por alunos do 12.º ano. A análise tentou demonstrar que aspetos enunciativos, como a dêixis e a polifonia, constituem fatores distintivos prototípicos destas duas sequências textuais, o que pode vir a facilitar a compreensão e produção de textos pelos alunos.The expository and argumentative sequences constitute the major textual sequences in different textual genres occupying a central focus (constituting one of its primary aims) in the recently reviewed program of the Portuguese discipline of secondary school. Although we argue that it is possible to analyze different textual genres based on basic textual sequences this relationship does not constitute our research goal. Instead, we have selected a subject no yet extensively studied, in the European Portuguese domain, even though it is relevant in our professional area: the enunciative dimension of the expository and argumentative textual sequences. Our aim is to contribute to the understanding of a pedagogically more accurate work about the textual sequences, since a deeper knowledge of textual structures and of their organization will enable students to recognize and use them in different textual genres. To attain our goals we have based our analysis mainly on Adam's work on textual sequences; for enunciation and deixis, we have resorted to the study by Benveniste and Kerbrat-Orecchioni, and the linguistic polyphony study was supported by studies of Ducrot, Vion and Fløttum. We extended Benveniste’s concept of ‘person’ by introducing the category of ‘point of view’, and as a result, we obtained a better notion of subjectivity and inter-subjectivity The study was supported by a corpus collected from expository and argumentative textual sequences produced by students of the 12th grade. The analysis seems to demonstrate that enunciative aspects, such as deixis and polyphony, are prototypical distinctive factors of these two textual sequences, which can facilitate the understanding and production of texts by students