In wireless packet-forwarding networks, the nodes or users are always selfish to maximize their utilities in nature. Selfish users would not like to help others for forward each others¡¦ packets, which will cause the network performance degrades severely. To solve the packet-forwarding problem, we propose a novel coalitional game approach based orthogonal decode-and-forward (ODF) relaying scheme to encourage the selfish users for cooperation. In the game-theoretic analysis, we study the properties and stability of the coalitions thoroughly. Furthermore, we prove that the cohesive behavior can be obtained by the aspect of outage probability indeed in this game. Simulation results show that the proposed ODF coalitional game can enforce cooperation exactly and it is always beneficial to form the cooperative groups for all users.

Este trabalho aborda a trajetória do PFL (Partido da Frente Liberal), desde a sua fundação em 1985 até 2010, quando já sob nova denominação DEM deixou de contar com seus três principais líderes: Jorge Bornhausen, Marco Maciel e Antônio Carlos Magalhães. A tese busca explicar as razões do sucesso do partido, até 2002, e de sua decadência a partir de então. Como principal hipótese, argumenta-se que a conexão com o governo federal foi a causa principal tanto do sucesso quanto da decadência da legenda, desencadeada pela passagem do PFL para a oposição após a vitória do Partido dos Trabalhadores na eleição presidencial de 2002. A análise da inserção do PFL no presidencialismo de coalizão e a narrativa da atuação dos três principais líderes do partido junto às altas esferas do governo federal foram os principais subsídios para a construção indutiva da comprovação da hipótese acima formulada. / This work addresses the path of the PFL (Partido da Frente Liberal), since its foundation in 1985 until 2010, when already under the new name - DEM - no longer count on its three main leaders: Jorge Bornhausen, Marco Maciel and Antonio Carlos Magalhães. The thesis seeks to explain the reasons for the party\'s success, until 2002, and its decline from then on. As the main hypothesis it is claimed that the connection to the federal government was the main cause of both, the success and the decline, triggered by the passage of the PFL to the opposition after the Workers Party (PT) victory in the presidential election of 2002. The analysis of PFL in the Brazilian coalitional presidentialism and the narrative of the three main important party leaders connections with high ranks of federal government provide the inductive proof of the above hypothesis.

This thesis comprises of two separate game theoretic models that fall under the general umbrella of network formation games. The first is a coalitional model of interaction in social networks that is based on the idea of social distance, in which players seek interactions with similar others. Our model captures some of the phenomena observed on such networks, such as homophily driven interactions and the formation of small worlds for groups of players. Using social distance games, we analyze the interactions between players on the network, study the properties of efficient and stable networks, relate them to the underlying graphical structure of the game, and give an approximation algorithm for finding optimal social welfare. We then show that efficient networks are not necessarily stable, and stable networks do not necessarily maximise welfare. We use the stability gap to investigate the welfare of stable coalition structures, and propose two new solution concepts with improved welfare guarantees. The second model is a compact formulation of matchings with externalities. Our formulation achieves tractability of the representation at the expense of full expressivity. We formulate a template of solution concept that applies to games where externalities are involved, and instantiate it in the context of optimistic, neutral, and pessimistic reasoning. Then we investigate the complexity of the representation in the context of many-to-many and one-to-one matchings, and provide both computational hardness results and polynomial time algorithms where applicable.

We first present a non-cooperative auction game to solve the bandwidth allocation problem for non-cooperative channel access in a wireless network. The Nash equilibrium is obtained as a solution of the game. To address this problem of bandwidth sharing under unknown information, we further develop a Bayesian auction game model and then Bayesian Nash equilibrium is then obtained. Next, we present a framework based on coalitional game for cooperative channel access for carry-and-forward-based data delivery. Each mobile node helps others to carry and then forward their data. A coalitional game is proposed to find a stable coalition structure for this cooperative data delivery. We next present static and dynamic coalitional games for carry-and-forward-based data delivery when the behavior of each mobile node is unknown by others. In the dynamic game, each mobile node can update its beliefs about other mobile nodes’ types when the static coalitional game is played repeatedly.

The focus of this thesis is on cooperative spectrum sensing and related security issues in multi-channel cognitive radio networks (MCCRNs). We first study the channel assignment for cooperative spectrum sensing in MCCRNs to maximize the number of available channels. In centralized implementation, a heuristic scheme is proposed along with a greedy scheme to reduce the reported information from the cognitive radios (CRs). In distributed scenario, a novel scheme with multi-round operation is designed following the coalitional game theory. Next, we focus on the physical layer security issues for cooperative spectrum sensing in MCCRNs, caused by Byzantine attacks. New counterattacks are proposed to combat attacks comprising coalition head and CRs as Byzantine attackers, which target to reduce the number of available channels for sensing in distributed MCCRNs. First, a new secure coalition head selection is proposed, by using statistical properties of the exchanged SNRs in the coalitions. Then, an iterative algorithm is proposed to block out attackers, if they continue attacking the system. The important problem of key management is considered next, and an energy-efficient identity-based and a certificate-based distributed key management schemes are proposed. First, a new elliptic curve cryptography (ECC)-based distributed private key generation scheme is proposed to combat the single point of failure problem along with novel distributed private key generator (DPKG) selection schemes to preserve security and energy-efficiency. Because of its importance in the proposed identity-based key management scheme, we further propose a low-complexity DPKG assignment, based on multi-objective programming, which can capture DPKG fairness in addition to energy-efficiency. Finally, a more powerful and intelligent distributed cooperative Byzantine attack on the proposed multi-channel cooperative spectrum sensing is proposed, where attackers collude by applying coalitional game theory to maximize the number of invaded channels in a distributed manner. As a remedy, a hierarchical identity-based key management scheme is proposed, in which CRs can only play on a certain number of requested channels and channel access for sensing is limited to the honest CRs selected in the coalitional game. Simulation results show that the proposed schemes can significantly improve cooperative spectrum sensing and secure the system against Byzantine attacks.

We first present a non-cooperative auction game to solve the bandwidth allocation problem for non-cooperative channel access in a wireless network. The Nash equilibrium is obtained as a solution of the game. To address this problem of bandwidth sharing under unknown information, we further develop a Bayesian auction game model and then Bayesian Nash equilibrium is then obtained. Next, we present a framework based on coalitional game for cooperative channel access for carry-and-forward-based data delivery. Each mobile node helps others to carry and then forward their data. A coalitional game is proposed to find a stable coalition structure for this cooperative data delivery. We next present static and dynamic coalitional games for carry-and-forward-based data delivery when the behavior of each mobile node is unknown by others. In the dynamic game, each mobile node can update its beliefs about other mobile nodes’ types when the static coalitional game is played repeatedly.

This thesis comprises of two separate game theoretic models that fall under the general umbrella of network formation games. The first is a coalitional model of interaction in social networks that is based on the idea of social distance, in which players seek interactions with similar others. Our model captures some of the phenomena observed on such networks, such as homophily driven interactions and the formation of small worlds for groups of players. Using social distance games, we analyze the interactions between players on the network, study the properties of efficient and stable networks, relate them to the underlying graphical structure of the game, and give an approximation algorithm for finding optimal social welfare. We then show that efficient networks are not necessarily stable, and stable networks do not necessarily maximise welfare. We use the stability gap to investigate the welfare of stable coalition structures, and propose two new solution concepts with improved welfare guarantees. The second model is a compact formulation of matchings with externalities. Our formulation achieves tractability of the representation at the expense of full expressivity. We formulate a template of solution concept that applies to games where externalities are involved, and instantiate it in the context of optimistic, neutral, and pessimistic reasoning. Then we investigate the complexity of the representation in the context of many-to-many and one-to-one matchings, and provide both computational hardness results and polynomial time algorithms where applicable.

abstract: California's Proposition 8 revoked the right to marriage for that state's gay and lesbian population. Proposition 8 was a devastating defeat for gay marriage movements across the nation. The primary rhetorical strategy of the No on 8 campaign was a reliance on a Civil Rights analogy that constructed the gay and lesbian movement for marriage as a civil right akin to those fought for by African Americans in the 1950s and 1960s. Analogizing the gay and lesbian struggle for gay marriage with the racial struggles of the Civil Rights Movement exposed a complicated relationship between communities of color and gay and lesbian communities. This project reads critical rhetoric and intersectionality together to craft a critical intersectional rhetoric to better understand the potentialities and pitfalls of analogizing the gay rights with Civil Rights. I analyze television ads, communiques of No on 8 leadership, as well as state level and national court decisions related to gay marriage to argue alternative frameworks that move away from analogizing and move towards coalition building. / Dissertation/Thesis / Ph.D. Communication 2011

The thesis deals with the transformation of the Brazilian Workers' Party (Partido dos Trabalhadores, PT). Its aim is to identify reasons for more than a decade interval between the renewal of direct presidential election under the universal suffrage and the victory of the left in a society that is marked by extreme inequality of wealth distribution. The second issue which is covered is how the party managed to consolidate power and keep it for three consecutive terms. Using modified concepts of mass, catch-all and cartel party the author tests the hypothesis that the electoral victory of the left was conditioned by the domination of the leftist side of political spectrum by the PT, as a result of building a mass (program-oriented) party, which subsequently tailored its campaign to focus on centrist voters (shift to the catch-all format, or votes-oriented party). The maintenance of power is based on crafting oversized coalitions with parties across the political spectrum, i.e. including the right-wing parties. However, these coalitions are created only to support government; the Workers' Party never forms electoral coalitions with prominent rightest parties. Furthermore, the thesis discusses the functioning of the so-called coalitional presidentialism, the typologies of current leftist governments in Latin America and also presents the basic elements of the Brazilian political system.

Este trabalho aborda a trajetória do PFL (Partido da Frente Liberal), desde a sua fundação em 1985 até 2010, quando já sob nova denominação DEM deixou de contar com seus três principais líderes: Jorge Bornhausen, Marco Maciel e Antônio Carlos Magalhães. A tese busca explicar as razões do sucesso do partido, até 2002, e de sua decadência a partir de então. Como principal hipótese, argumenta-se que a conexão com o governo federal foi a causa principal tanto do sucesso quanto da decadência da legenda, desencadeada pela passagem do PFL para a oposição após a vitória do Partido dos Trabalhadores na eleição presidencial de 2002. A análise da inserção do PFL no presidencialismo de coalizão e a narrativa da atuação dos três principais líderes do partido junto às altas esferas do governo federal foram os principais subsídios para a construção indutiva da comprovação da hipótese acima formulada. / This work addresses the path of the PFL (Partido da Frente Liberal), since its foundation in 1985 until 2010, when already under the new name - DEM - no longer count on its three main leaders: Jorge Bornhausen, Marco Maciel and Antonio Carlos Magalhães. The thesis seeks to explain the reasons for the party\'s success, until 2002, and its decline from then on. As the main hypothesis it is claimed that the connection to the federal government was the main cause of both, the success and the decline, triggered by the passage of the PFL to the opposition after the Workers Party (PT) victory in the presidential election of 2002. The analysis of PFL in the Brazilian coalitional presidentialism and the narrative of the three main important party leaders connections with high ranks of federal government provide the inductive proof of the above hypothesis.