In the recent years, prices of art have repeatedly broken records, and the interest in investing in fine art photography has been growing. Although there is plenty of research dedicated to studying prices of paintings, fine art photography has been largely overlooked. This thesis aims to shed light on identifying price determinants for this particular medium. A new data set is collected from sold lot archives of Sotheby's and Phillips auction houses, which also provide images of some of the sold items. These images are then used to create new variables describing visual attributes of the artworks. In order to inspect the effect of color-related predictors on price, four different methods are discussed. Color is found to be significant in OLS model, but the effect diminishes when model averaging is applied. Machine learning al- gorithms - regression trees and random forests - suggest that the importance of color is relatively low. The thesis also shows that expert estimates can improved by incorporating available information and using random forests for prediction. The fact that the expert estimates are not very accurate sug- gest that they either do not use all the available information or they do not process it efficiently. 1

Dans cette thèse nous étudions formellement la sécurité des protocoles de vote et d'enchère en ligne. Le vote en ligne est utilisé en Estonie et dans certaines régions de la Suisse. D'autre part, les enchères en ligne sont de plus en plus populaires: eBay comptait plus de 112 millions utilisateurs actifs et plus de 350 millions d'objets à vendre en 2012, avec un chiffre d'affaires de 14 milliards de dollars. Dans ces deux applications, la sécurité est primordiale, à cause d'enjeux financiers et politiques. Dans le cas des protocoles de vote, le secret du vote est crucial pour le libre choix des votants. Nous proposons une hiérarchie des notions de secret du vote par rapport à plusieurs niveaux de coercition, des attaques spécifiques (comme l'abstention forcé), et des votants corrompus. Nous développons également des notions généralisées pour le cas des votes pondérés (par exemple par rapport au nombre d'actions dans une société), et montrons que pour beaucoup de protocoles le cas avec plusieurs votants sous attaque se réduit au cas avec un seul votant sous attaque. Ce résultat a été obtenu grâce à un autre résultat dans le pi-calcul appliqué montrant que tout processus fini peut se décomposer de manière unique en processus premiers. Nous illustrons notre hiérarchie sur plusieurs exemples, soulignant comment elle permet d'évaluer le niveau d'anonymat d'un protocole donné. Dans le cas des protocoles d'enchère en ligne, nous proposons aussi une hiérarchie de notions d'anonymat, et plusieurs notions d'équité et d'authentification comme la non-interférence, la non-annulation et la non-répudiation. Nous analysons ces propriétés automatiquement à l'aide de l'outil ProVerif sur trois exemples, et découvrons plusieurs faiblesses. De plus, nous proposons une définition abstraite de la vérifiabilité, et l'appliquons sur des exemples aussi bien dans le modèle calculatoire que dans le modèle symbolique en utilisant CryptoVerif et ProVerif respectivement. Nous démontrons dans le modèle calculatoire qu'un des protocoles est vérifiable, et découvrons plusieurs faiblesses sur le deuxième exemple. Finalement nous étudions le concept d'«enchères vraiment vérifiable par les enchérisseurs», c'est-à-dire des protocoles d'enchère ou le bon déroulement peut être vérifié par un non-expert, car la sécurité est assurée par des moyens physiques, et non cryptographiques. Nous proposons deux tels protocoles, et une analyse formelle de ces protocoles avec ProVerif grâce à une modélisation symbolique des propriétés physiques. / In this document, we formally analyze security in electronic voting and electronic auctions. On-line voting over is now available in several countries, for example in Estonia or parts of Switzerland. Similarly, electronic auctions are increasingly used: eBay had over 112 million active users and over 350 million listings in 2012, and achieved a revenue of more than 14 billion US Dollars. In both applications, security is a main concern, as fairness is important and money is at stake. In the case of voting protocols, privacy is crucial to ensure free elections. We propose a hierarchy of privacy notions in the Applied Pi-Calculus, including different levels of coercion, special attacks such as forced-abstention attacks, and inside attackers. We also provide generalized notions for situations where votes are weighted (e.g. according to the number of shares in a company), and show that for many protocols the case with multiple coerced voters can be reduced to the case with one coerced voter. This result is made possible by a unique decomposition result in the Applied Pi-Calculus showing that any finite process has a unique normal form with respect to labeled bisimilarity. Moreover we provide multiple case studies illustrating how our taxonomy allows to assess the level of privacy ensured by a voting protocol. In the case of auction protocols we also consider a hierarchy of privacy notions, and several fairness and authentication properties such as Non-Interference, Non-Cancellation and Non-Repudiation. We analyze all these properties automatically using ProVerif on three case studies, and identify several flaws. Moreover we give an abstract definition of verifiability in auctions and provide case studies in the symbolic and computational model using ProVerif and CryptoVerif respectively. Again, we identify several shortcomings, but also give a computational proof for one protocol. Finally we explore the idea of ``true bidder-verifiable auctions'', i.e. auctions that can be verified by a non-expert, as the property is ensured through physical properties instead of complex cryptography. We propose two such protocols, discuss how to model the underlying physical properties, and provide a formal analysis of both protocols using ProVerif.

Orientador: Paulo de Barros Correia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T16:27:15Z (GMT). No. of bitstreams: 1 Silva_ElisaBastos_M.pdf: 3100483 bytes, checksum: 2b4732216b84c9d54a500b4c235db376 (MD5) Previous issue date: 2011 / Resumo: Os mecanismos de comercialização de energia elétrica foram modificados pelo Governo por meio do novo modelo do setor elétrico instituído em 2004. Esse procedimento foi definido, elegendo-se os leilões como forma de licitação para o ambiente de contratação regulada, objetivando minimizar os preços de venda (aproximando-os do custo de produção) e introduzir a competição de mercado. O mecanismo de leilões, no âmbito do setor elétrico, foi adotado por diversos países, que nem sempre obtiveram níveis elevados de. Entretanto, apesar das experiências de insucesso, verifica-se a necessidade de se comercializar energia elétrica através de contratos de longo prazo; logo a formatação dos leilões deve prever diversos aspectos com vista a evitar tais insucessos. Por isso, para o setor elétrico brasileiro, anualmente, são descritas pelo MME uma série de diretrizes em que constam os procedimentos para habilitação técnica, prazos e sistemática adotada para esses leilões. Em esfera nacional, os leilões são classificados como: leilão de linha de transmissão, leilão de energia existente, leilão de energia de ajuste, leilões de reserva e leilão de energia nova. Os leilões de novos empreendimentos tendem à expansão da oferta; são constituídos por aqueles que não sejam detentores de concessão, permissão, autorização, ou ainda, por aqueles que visam à ampliação de parte dos empreendimentos existentes. Esses leilões são, comumente, formatados de maneira sequencial. A proposta dessa dissertação é a avaliação metodológica para leilão de novos empreendimentos de geração, de formato híbrido, utilizando-se os conceitos de leilões simultâneos e combinatórios. Dessa forma se obtém uma análise na ótica do leiloeiro, a fim de aumentar a competição nesse segmento e reduzir o valor do MWh. A simulação do leilão obteve resultados satisfatórios, dada a sua complexidade computacional; assim sendo, essa metodologia mostrou-se adequada e viável para o mercado de energia elétrica / Abstract: The mechanisms of trading energy, established in the model of the electric sector in 2004, were modified by the Government. Such procedure was defined, electing the auctions as a way of bidding for the regulated contract environment, in order to minimize the selling prices (approaching them of the cost production) and to introduce the market competition. The procedure of auctions, in the electric sector, was adopted by several countries, but not always they achieved the perfect competition. However, despite the experience of failure, there is a need to commercialize electric energy in the long term; so the format of the auction should include several aspects in order to avoid such failures. Therefore, for the Brazilian electric sector, annually, are described by the MME a series of guidelines, which include the procedures for technical qualifications, stated periods and the systematic adopted. At national level, the auctions are classified as: transmission line auction, existing ventures auctions, energy adjustment auction, reserve auctions and new ventures auction. The auctions of new ventures tend to supply expansion, they are made by those who are not holders of concession, permission authorization, or even by those who seek the expansion of part of existing projects. These auctions are generally formatted in sequential way.The purpose of this master thesis is the methodological evaluation of an auction of new ventures auctions, of hybrid format, using the concepts of combinatorial and simultaneous auctions. Of this way it gets an analysis based in the auctioneer optics, in order to increase the competition in this segment and to reduce the price per MWh. The simulations of the auction got resulted satisfactory, given its computational complexity, and thus being this methodology proved to be appropriate and feasible to the market of electric energy / Mestrado / Mestre em Planejamento de Sistemas Energéticos

Neste projeto apresentamos três modelos para publicidade na Internet, e mecanismos associados a cada modelo, analisando suas propriedades como estabilidade, otimalidade, prova de estratégia, e consumo de tempo. Primeiramente apresentamos um dos primeiros artigos publicados sobre o problema de leilões para publicidade na Internet, que descreve essencialmente o funcionamento dos atuais leilões para publidade na Internet. Em seguida, apresentamos outros dois modelos. O primeiro deles permite publicidade com exclusividade. O segundo modelo permite mais opções ao leiloeiro e aos anunciantes, ao permitir preços mínimos de venda e preços máximos de compra. / In this project we present three Internet sponsored search advertising models, and mechanisms related to each model, analyzing properties such as stability, optimality, strategy-proof, and time consumption. We start presenting one of the first articles on the problem of sponsored search advertising. Next, we present other two models. The first one allows exclusivity advertising. The second model allows a wider variety of options for both the auctioneer and the bidders, including minimum selling prices and maximum buying prices.

Submitted by André Silva Almeida (ansial@fgvmail.br) on 2013-11-03T20:38:56Z No. of bitstreams: 1 Dissertação de Mestrado - André Almeida.pdf: 3036708 bytes, checksum: f5e9d98bba824c492f931f0e8fa4ae69 (MD5) / Approved for entry into archive by Janete de Oliveira Feitosa (janete.feitosa@fgv.br) on 2013-12-17T11:28:40Z (GMT) No. of bitstreams: 1 Dissertação de Mestrado - André Almeida.pdf: 3036708 bytes, checksum: f5e9d98bba824c492f931f0e8fa4ae69 (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2013-12-19T16:37:12Z (GMT) No. of bitstreams: 1 Dissertação de Mestrado - André Almeida.pdf: 3036708 bytes, checksum: f5e9d98bba824c492f931f0e8fa4ae69 (MD5) / Made available in DSpace on 2013-12-19T16:37:41Z (GMT). No. of bitstreams: 1 Dissertação de Mestrado - André Almeida.pdf: 3036708 bytes, checksum: f5e9d98bba824c492f931f0e8fa4ae69 (MD5) / This work considers the application of computer simulation as a method of deepening the study of mechanisms for auctions applied in the allocation of oil exploitation rights in the pre-salt layer. The pre-salt layer is located in the Brazilian coast and presents a large potential in terms of barrel of oil equivalent. Based on an experimental data, the bid function was estimated as an exponential function and applied at the participants created computationally. Considering all features and parameters of the experiments, the simulation allows to reproduce the auction model without incurring implementation costs on new auction sessions with real participants. The auction models studied were the rst-price sealed-bid auction and the second-price sealed-bid auction. The results show that the rst-price sealed-bid auctions are less risky than the second-price sealed-bid auctions; the Revenue Equivalence Principle is valid on symmetric auctions; asymmetric auctions present lower e ciency compared to the rst-price auction; the second-price auction presents a tra- deo between e ciency and government revenue; and considering participant learning, were not observed signi cant changes on the statistics analyzed as the participants become more experienced. / O presente trabalho consiste na aplicação da simulação computacional como método de aprofundamento do estudo de mecanismos de leilões aplicados na alocação do direito de exploração das reservas de petróleo da camada do pré-sal. A camada do pré-sal está localizada na costa brasileira e apresenta um grande potencial em termos de reserva de óleo e gás. A função lance aplicada para os participantes criados computacionalmente foi estimada com base em dados experimentais e segue uma função exponencial. A simulação possibilita reproduzir o modelo de leilão considerando todas as características e parâmetros dos experimentos sem incorrer no custo da realização de novas sessões de leilão com participantes reais. Os leilões estudados foram o leilão de valores privados de 1° preço e o leilão de valores privados de 2° preço. Através dos resultados obtidos identificou-se que o leilão de valores privados de 1° preço é menos arriscado que o leilão de valores privados de 2° preço; no leilão com simetria, o Princípio de Equivalência de Receita é válido; a eficiência observada é menor em leilões assimétricos; o leilão de 2° preço comparado com o de 1° preço apresenta um tradeoff entre a eficiência e a receita do governo; e que considerando o aprendizado dos participantes, não se observam alterações significativas nas estatísticas analisadas à medida que os participantes se tornam mais experientes.

Investigate the use of partial relations for multicriteria reverse auctions. At first, a theoretical framework is introduced. Then, an extension of traditional multicriteria tools is considered. This is referred to as the Butterfly model. Finally, the concept of Bidding Niches partitions is formalized and tested. / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

[pt] Uma questão importante em sistemas baseados em agentes é como executar uma ação planejada de uma maneira aleatória. Saber responder esta questão é fundamental para manter o interesse do usuário em um determinado produto, não apenas porque torna a experiência menos repetitiva, mas também porque a torna mais realista. Este tipo de execução de ações pode ser aplicado principalmente em simuladores, jogos sérios ou de entretenimento que se baseiam em modelos de agentes. Algumas vezes, a aleatoriedade pode ser obtida pela simples geração de números aleatórios. Porém, quando estamos criando um produto mais complexo, é recomendável usar algum conhecimento estatístico ou estocástico para não arruinar a experiência de consumo deste produto. Neste trabalho, nós damos suporte à criação de animações e histórias dinâmicas e interativas usando um modelo arbitrário baseado em agentes. Para isto, inspirado em métodos estocásticos, nós propomos um novo framework, chamado D-Engine, que é capaz de criar um conjunto de timestamps aleatórios, mas com um comportamento esperado bem conhecido, que descrevem a execução de ações em regime de tempo discreto e a uma determinada taxa. Ao mesmo tempo em que estes timestamps nos permitem animar uma história, uma ação ou uma cena, os resultados gerados com o nosso framework podem ser usados para auxiliar outras aplicações, tais como previsões de resultado, planejamento não determinístico, mídia interativa e criação de estórias. Nesta dissertação também mostramos como criar dois aplicativos diferentes usando o framework proposto: um cenário de duelo em um jogo e um site de leilões interativo. / [en] An important question in agent-based systems is how to execute some planned action in a random way. The answer for this question is fundamental to keep the user s interest in some product, not just because it makes the experience less repetitive but also because it makes the product more realistic. This kind of action execution can be mainly applied on simulators, serious and entertainment games based on agent models. Sometimes the randomness can be reached by just generating random numbers. However, when creating a more complex product, it is recommended to use some statistical or stochastic knowledge to not ruin the product s consumption experience. In this work we try to give support to the creation of dynamic and interactive animation and story using an arbitrary model based on agents. Inspired on stochastic methods, we propose a new framework called D-Engine, which is able to create a random, but with a well-known expected behavior, set of timestamps describing the execution of an action in a discrete way following some specific rate. While these timestamps allow us to animate a story, an action or a scene, the mathematical results generated with our framework can be used to aid other applications such as result forecasting, nondeterministic planning, interactive media and storytelling. In this work we also present how to implement two different applications using our framework: a duel scenario and an interactive online auction website.

The purposes of the study were to: 1) identify the underlying dimensions of consumer shopping motivations and attitudes toward online auction behaviors; 2) examine the relationships between shopping motivations and online auction behaviors; and 3) examine the relationships between shopping attitudes and online auction behaviors. Students (N = 341) enrolled at the University of North Texas completed self-administered questionnaires measuring shopping motivations, attitudes, online auction behaviors, and demographic characteristics. Using multiple regression analyses to test the hypothesized relationships, shopping motivations and shopping attitudes were significantly related to online auction behaviors. Understanding the relationships is beneficial for companies that seek to retain customers and increase their sales through online auction.

Dans le premier chapitre, j'examine si les vendeurs à découvert sont mieux informés à propos des enchères d'obligation souveraines que le marché. Je trouve, en moyenne, une forte augmentation de la demande de vente à découvert avant les enchères. Néanmoins, la demande de vente à découvert ne prédit pas une augmentation future du rendement. Les vendeurs à découvert ne sont donc pas mieux informés sur le résultat des enchères et n'interprètent pas mieux que le marché.Dans le second chapitre, je développe et teste un modèle expliquant la baisse graduelle des prix observée dans les jours qui conduisent à des ventes anticipées d'actifs telles que les enchères du Trésor. Dans le modèle, les investisseurs averses au risque anticipent une vente d'actifs dont l'ampleur − et donc le prix − sont incertains. Je montre que les investisseurs font face à un compromis entre se hedger au moyen d'une position longue et spéculer sur la différence entre le prix avant la vente et le prix espéré de vente. En raison du hedging, le prix d'équilibre est supérieur au prix de vente espéré. À l'approche de la date de vente, l'incertitude quant au prix de vente diminue, les positions spéculatives à découvert augmentent et le prix diminue. Conformément aux prédictions, je trouve que le rendement des bons du Trésor italien augmente de 1,2 points de base après la publication d'informations sur le prix d'enchère, par rapport aux jours sans information.Dans le troisième chapitre, j'étudie le lien entre les prix et les taux repo au cours de la crise des subprimes. Je trouve que la relation de non-arbitrage entre les prix et les taux repo de Duffie (1996) performe moins bien pendant la crise. Cependant, les obligations à faible taux repo ont 18.0% plus de chance d'être plus coûteuses que les obligations identiques à taux repo élevé lors de la crise, contre seulement 9.0% avant la crise. Dans l'ensemble, bien qu'il existe de fortes limites à l'arbitrage, les prix et les taux repo présentent des co-mouvements plus importants pendant la crise. / In the first chapter, I ask if short-sellers are superiorly informed about sovereign auctions. I find a large average increase in demand for short-selling prior to auctions. Yet, the demand for short-selling a bond does not predict a subsequent increase in the bond's yield. Overall, there is no evidence that short-sellers predict or interpret auction outcomes better than the market.In the second chapter, I develop and test a model explaining the gradual price decrease observed in the days leading to large anticipated asset sales such as Treasury auctions. In the model, risk-averse investors anticipate an asset sale which magnitude, and hence price, are uncertain. I show that investors face a trade-off between hedging the price risk with a long position, and speculating on the difference between the pre-sale and the expected sale prices. Due to hedging, the equilibrium price is above the expected sale price. As the sale date approaches, uncertainty about the sale price decreases, short speculative positions increase and the price decreases. In line with the predictions, I find that the yield of Italian Treasuries increases by 1.2 bps after the release of auction price information, compared to non-information days.In the third chapter, I study the link between prices and repo rates during the subprime crisis. I find that the no-arbitrage relationship between prices and repo rates in Duffie (1996) fares worse during the crisis. However, low-repo-rate bonds have an 18.0% higher probability of being more expensive than identical high-repo-rate bonds during the crisis, compared to only 9.0% before the crisis. Overall, while there are high limits of arbitrage, prices and repo rates feature larger co-movements during the crisis.

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