Differential Privacy: on the trade-off between Utility and Information Leakage

Differential privacy is a notion of privacy that has become very popular in the database community. Roughly, the idea is that a randomized query mechanism provides sufficient privacy protection if the ratio between the probabilities that two adjacent datasets give the same answer is bound by e^epsilon. In the field of information flow there is a similar concern for controlling information leakage, i.e. limiting the possibility of inferring the secret information from the observables. In recent years, researchers have proposed to quantify the leakage in terms of R\'enyi min mutual information, a notion strictly related to the Bayes risk. In this paper, we show how to model the query system in terms of an information-theoretic channel, and we compare the notion of differential privacy with that of mutual information. We show that differential privacy implies a bound on the mutual information (but not vice-versa). Furthermore, we show that our bound is tight. Then, we consider the utility of the randomization mechanism, which represents how close the randomized answers are, in average, to the real ones. We show that the notion of differential privacy implies a bound on utility, also tight, and we propose a method that under certain conditions builds an optimal randomization mechanism, i.e. a mechanism which provides the best utility while guaranteeing differential privacy.Comment: 30 pages; HAL repositor

Huawei case study : a reposition challenge to achieve leadership

Having as a focus the practical dilemma of Huawei’s repositioning strategy in Portugal, the present dissertation places under analysis the efficiency of the brand’s strategy evaluated through the changes in consumers’ perceptions, and therefore, market acquisition. Huawei is a Chinese IT solutions provider since 1987. Placing the client at the center of their activities, the brand aims to offer the best experience to its consumers through their smartphones. Through strategic partnerships with well-known partners, the brand aims to build a better-connected world, acquiring the number one spot as the most preferable and trustworthy brand of its target audience. Nevertheless, Huawei entered the Portuguese market with low-quality equipment, usually the operators private labels, associated to a low performance, trust, and durability. Therefore, the brand still suffers nowadays with the consequences of this association, not be-ing seen by consumers as a trustworthy brand of reference, even with its products being of high performance and quality, a result of the great investment made in R&D. As a response to this market’s perception, the brand went through a repositioning strategy. Thus, it is intended to study, through primary and secondary research, if the repositioning strategy of Huawei managed to change the it market’s perception, and if there was actually an added value to the consumer. The main results demonstrate that the brand’s market perception is under high evolution, hav-ing acquired a favorable opinion with its consumers, which if maintained in the long-term, it will lead to buying intentions.como foco o dilema do reposicionamento da Huawei em Portugal, a presente dissertação coloca sob análise a eficiência da estratégia da marca avaliada através da alteração da percepção dos consumidores e consequente conquista de mercado. A Huawei é uma marca Chinesa, que fornece soluções de Tecnologia integradas desde 1987. Colocando o cliente no centro da sua actividade, a marca procura oferecer a melhor experiência aos seus consumidores através dos seus smartphones. Através de parcerias estratégicas, com parceiros de renome, ambiciona construir um mundo mais conectado e conquistar o lugar de marca preferida e de confiança dos consumidores. No entanto, a Huawei entrou no mercado Português com telemóveis de baixa gama, sendo muitas vezes os equipamentos de marca branca dos operadores reflexo de baixo desempenho, confiança e durabilidade. Consequentemente, a marca sofre ainda hoje com as consequências desta associação, não sendo vista pelos consumidores como uma marca de referencia e confiança apesar dos seus produtos serem actualmente de enorme desempenho e qualidade graças à grande aposta da marca em investigação e desenvolvimento. Em resposta a esta percepção de mercado a marca reposicionou-se. Assim, pretende-se estudar, através de pesquisa primária e secundária, se o reposicionamento estratégico da marca alterou as percepções de mercado sobre a Huawei representando actualmente um valor acrescentado para o consumidor. Os principais resultados mostraram que a percepção da marca está em grande evolução, tendo conquistado uma opinião favorável junto dos consumidores, factor que a manter-se a longo prazo conduzirá a intenções de compra

Vista Alegre Atlantis investment committee paper - valuation

The proposed Investment Committee Paper is intended for academic purposes only. The project aims to study a private equity deal using a Leveraged Buyout (LBO) for Vista Alegre Atlantis (VAA), a market leader in the ceramic and glass tableware sector. Our goal is to understand how the LBO could be structured, what returns it could provide, and what exit strategies can be pursued. In addition, we will focus on analysing and forecasting the business plan and defining the optimal capital structure. The conclusion is that VAA is an attractive investment opportunity, able to leverage the market's growth

Viabilidade de implantacao de aveia em pastagens estabelecidas de capim-elefante.

bitstream/item/142996/1/2033.pd

Fake news: characterization of different individual profiles in relation to different news topics

Project Work presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Information Systems and Technologies ManagementThe existence of fake news is an extremely topical concern which calls into question the veracity of the broadcasted information. Since nowadays the search and production of news is mainly done online, the costs with content production are low and the content’s reach and speed of propagation is very high. These factors facilitate the dissemination of fake news in social platforms that are not specialized means of communication, namely in online social networks. Therefore, this study aims to characterize different profiles of Portuguese individuals based on their susceptibility to several news topics. The attainment of the mentioned profiles is going to be a valuable contribution to information management and it is going to allow future definition of measures to mitigate the propagation of fake news in social platforms. To achieve this, critical literature review was done and accompanied by the creation of a survey to analyze how academic background and topic of the news pieces influence the accuracy of individuals identifying false news. This dissertation intents to understand if there is anyone immune to fake news, or if individuals can be more or less immune depending on the topic

As diversas faces dos embargos de declaração

- Disponível também na Revista de Processo: RePro, v. 30, n. 130, p. 11-18, dez. 2005

On the information leakage of differentially-private mechanisms

International audienceDifferential privacy aims at protecting the privacy of participants instatistical databases. Roughly, a mechanism satisfies differential privacy ifthe presence or value of a single individual in the database does notsignificantly change the likelihood of obtaining a certain answer to anystatistical query posed by a data analyst. Differentially-private mechanisms areoften oblivious: first the query is processed on the database to produce a trueanswer, and then this answer is adequately randomized before being reported tothe data analyst. Ideally, a mechanism should minimize leakage, i.e., obfuscateas much as possible the link between reported answers and individuals' data,while maximizing utility, i.e., report answers as similar as possible to thetrue ones. These two goals, however, are in conflict with each other, thusimposing a trade-off between privacy and utility.In this paper we use quantitative information flow principles to analyze leakageand utility in oblivious differentially-private mechanisms. We introduce atechnique that exploits graph symmetries of the adjacency relation on databasesto derive bounds on the min-entropy leakage of the mechanism. We consider anotion of utility based on identity gain functions, which is closely related tomin-entropy leakage, and we derive bounds for it. Finally, given some graphsymmetries, we provide a mechanism that maximizes utility while preserving therequired level of differential privacy