nÃo hà / O presente trabalho tem como objetivo principal identificar o efeito competitivo da fusÃo entre Sadia e PerdigÃo, no mercado de alimentos do Brasil. Como ambas as empresas possuem aÃÃes na Bolsa de Valores, um bom mÃtodo para verificar esse efeito competitivo à o Estudo de Eventos. Essa metodologia tem como mÃrito, a objetividade, podendo inferir sobre hipÃteses relativamente simples: se a fusÃo for prÃcompetitiva, os ditos retornos anormais das rivais Ãs firmas fusionadas apresentarÃo sinais negativos, caso contrÃrio, a fusÃo poderà ser considerada anticompetitiva. Para base de dados, usamos como fonte, o IBOVESPA, alÃm de dados da ECONOMÃTICA. O modelo economÃtrico à um tradicional MQO. Os retornos, dentro da trajetÃria normal dos ativos financeiros serÃo calculados a partir de uma janela de estimaÃÃo e, os retornos anormais serÃo calculados dentro da janela do evento. Testes serÃo feitos para verificar a significÃncia estatÃstica desses dados. Os resultados do trabalho mostram que a fusÃo nÃo pode ser considerada prÃcompetitiva, os quais sÃo consistentes com a decisÃo do CADE. / This study's main objective is to try to identify the competitive effect of the merger between Sadia and PerdigÃo in the food market in Brazil. Since both companies have shares in the Stock Exchange, a good method to check this competitive effect is by using the Event Study. This methodology has the merit objectivity and may result in relatively simple cases: if the merger is procompetitive , the abnormal returns of rivals of the merged firms showed negative signs, otherwise, the merger may be considered anticompetitive. For database, it was used as source the Ibovespa, and data ECONOMATICA. The econometric model is a traditional OLS. The returns within the normal trajectory of financial assets will be calculated from a estimation window and the abnormal returns are calculated within the event window. Tests will be done to check the statistical significance of the data. Results of the study show that the merger can not be considered procompetitive. Results consistent with the decision of CADE.

Η διατριβή χωρίζεται σε δύο μέρη. Στο Μέρος Α' χρησιμοποιούνται μαθηματικές μέθοδοι της Θεωρίας Παιγνίων και των Δυναμικών Συστημάτων για να μελετηθεί η κανονική και χαοτική δυναμική διαφόρων μοντέλων της Μικροοικονομίας. Βασικά αποτελέσματα είναι η μετάβαση σε συνθήκες πλήρους ανταγωνισμού και η διαφοροποίηση του παραγόμενου προιόντος σε ένα δυοπώλιο-τριοπώλιο. Στο Μέρος Β', κύριος στόχος της έρευνας ήταν να συνδεθούν ορισμένες από τις πλέον γνωστές μερικές διαφορικές εξισώσεις (ΜΔΕ) που χρησιμοποιούνται στα Οικονομικά Μαθηματικά και Χρηματοοικονομικά, με την εξίσωση της θερμότητας της Μαθηματικής Φυσικής, εφαρμόζοντας την κατά Lie συμμετρίες ανάλυση. Επίσης η ανάλυση αυτή αποδείχθηκε ιδιαίτερα ισχυρή για την εύρεση αλγεβρικών δομών εξισώσεων που περιγράφουν την τιμολόγηση αγαθών. Έτσι, οδηγούμαστε με συστηματικό τρόπο όχι μόνο στην εύρεση νέων λύσεων αλλά και στην ανακάλυψη κομψών γενικεύσεων των εξισώσεων αυτών. / The thesis is divided into two parts. In Part One we use the mathematical methods of Game Theory and Dynamical Systems to study the stable and chaotic dynamics of various models in Microeconomics. Some of our main results are the route to perfect competition and the differentiation of goods in a duopoly and in a triopoly. In Part Two, our main concern was to link some of the most well-known partial differential equations that are encountered in Economics and Financial Mathematics, with the heat equation of Mathematical Physics, using Lie symmetry analysis. More to that, this analysis proved extremely powerful to the finding of interesting algebraic properties for equations that describe the pricing of commodities. In such way, we succeed in presenting, in a systematic fashion, not only new solutions, but also elegant generalisations of the equations under investigation.