Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-05-24T21:33:25Z No. of bitstreams: 1 EdileideSantosLima.pdf: 1928796 bytes, checksum: 7cd66567aa5ea1fea56f0f328c6adfcb (MD5) / Made available in DSpace on 2017-05-24T21:33:25Z (GMT). No. of bitstreams: 1 EdileideSantosLima.pdf: 1928796 bytes, checksum: 7cd66567aa5ea1fea56f0f328c6adfcb (MD5) Previous issue date: 2015-07-31 / The growth of distance learning in Brazil is a reality - mainly the undergraduate courses since its regularization by the LDB 9394/96 (decree 5.622 from 2005) and the appearance of Brazil Open University (UAB). Despite the growth of this kind of education, there is a problem that worries everyone: its significant evasion. Thus, this dissertation is the result of a survey about evasion concerning the Education undergraduate Course, held at the State University in Maranhão (UEMA) - specifically in the Technology Center for Education (UemaNet). This study aimed at investigating the causes of evasion in the Education undergraduate Course (distance learning) from 2009 to 2013. In order to have this research carried out, a quantitative and qualitative study, a case study, as well as an on-line questionnaire applied to the course general coordination, local coordination, tutors and dropout students from the period mentioned were held to understand the administrative and pedagogical structure of the course and the causes of evasion. In addition, bibliographic and documentary analysis was performed with the aim at better understanding the investigated object. After collection, quantitative data were analyzed using descriptive statistics and qualitative data were studied through content analysis. It was concluded that the escape was the result of a number of factors, from personal, pedagogical, technological and interaction, including the most significant were the personal aspects. / O crescimento de cursos a distância no Brasil é uma realidade, principalmente, os de graduação, desde a sua regularização na LDB 9394/96, no decreto 5.622 de 2005 e do surgimento da Universidade Aberta do Brasil (UAB). Apesar do crescimento dessa modalidade de ensino, há uma problemática que preocupa a todos, trata-se da evasão que é significativa. Dessa forma, essa dissertação é resultado de uma pesquisa realizada acerca da evasão no curso de Licenciatura em Pedagogia na modalidade a distância, realizada na Universidade Estadual do Maranhão (UEMA) mediada pelo Núcleo de Tecnologias para a Educação (UemaNet). Objetivou-se, investigar as causas da evasão no curso de Licenciatura em Pedagogia na modalidade a distância no período de 2009 a 2013. Empreendeu-se um estudo misto, quantitativo e qualitativo, um estudo de caso, utilizando-se para a coleta de dados, o questionário online para a coordenação de curso, a coordenação de polo presencial, os tutores a distância e os alunos evadidos do no período citado com a finalidade de entender a estrutura administrativa e pedagógica do referido curso, bem como as causas da evasão. Além disso, foi realizada pesquisa bibliográfica e análise documental com o intuito de melhor entender o objeto investigado. Após a coleta de dados, os quantitativos foram analisados por meio de estatística descritiva e os qualitativos pela análise de conteúdo. Concluiu-se que a evasão é resultado de um conjunto de fatores desde aspectos pessoais, pedagógicos, tecnológicos e de interação, dentre eles o mais significativo foram os aspectos pessoais.

Simulating large numbers of agents, performing complex behaviors in realistic environments is a difficult problem with applications in robotics, computer graphics and animation. A multi-agent system can be a useful tool for studying a range of situations in simulation in order to plan and train for actual events. Systems supporting such simulations can be used to study and train for emergency or disaster scenarios including search and rescue, civilian crowd control, evacuation of a building, and many other training situations. This work describes our approach to multi-agent systems which integrates a roadmap-based approach with agent-based systems for groups of agents performing a wide range of behaviors. The system that we have developed is highly customizable and allows us to study a variety of behaviors and scenarios. The system is tunable in the kinds of agents that can exist and parameters that describe the agents. The agents can have any number of behaviors which dictate how they react throughout a simulation. Aspects that are unique to our approach to multi-agent group behavior are the environmental encoding that the agents use when navigating and the extensive usage of the roadmap in our behavioral framework. Our roadmap-based approach can be utilized to encode both basic and very complex environments which include multi- level buildings, terrains and stadiums. In this work, we develop techniques to improve the simulation of multi-agent systems. The movement strategies we have developed can be used to validate agent movement in a simulated environment and evaluate building designs by varying portions of the environment to see the effect on pedestrian flow. The strategies we develop for searching and tracking improve the ability of agents within our roadmap-based framework to clear areas and track agents in realistic environments. The application focus of this work is on pursuit-evasion and evacuation planning. In pursuit-evasion, one group of agents, the pursuers, attempts to find and capture another set of agents, the evaders. The evaders have a goal of avoiding the pursuers. In evacuation planning, the evacuating agents attempt to find valid paths through potentially complex environments to a safe goal location determined by their environmental knowledge. Another group of agents, the directors may attempt to guide the evacuating agents. These applications require the behaviors created to be tunable to a range of scenarios so they can reflect real-world reactions by agents. They also potentially require interaction and coordination between agents in order to improve the realism of the scenario being studied. These applications illustrate the scalability of our system in terms of the number of agents that can be supported, the kinds of realistic environments that can be handled, and behaviors that can be simulated.

This dissertation analyzes the optimal mix of direct and indirect taxes in an economy with multiple tax collecting authorities when both the taxes are subject to evasion and to what extent the tax compliance behavior of individuals in the United States are persistent and spatially dependent. Essay I derives and provides an intuitive interpretation of: (i) impact of the changes in the government instruments on tax evasion by firms, the expected prices they charge, and the expected tax rates they face; (ii) a generalized version of Ramsey rule for optimal commodity taxation which accounts for income tax evasion from either or both the tax authorities; (iii) generalized formulae for the optimal income tax rate for each of the tax authorities; and (iv) the tradeoff between optimal tax rates and audit probabilities for each of the tax authorities. It also re-examines controversies surrounding the uniform income taxes and the differentiated commodity taxes, and investigates how income tax evasion affects the progressivity of the income tax rates. It concludes that whether or not tax evasion calls for reductions in the optimal income tax rates hinges on how tax evasion and the associated concealment costs vary across individual taxpayers. Essay II introduces the twin issues of spatiality and persistence in the individual income tax evasion. While the issue of persistence arises through accumulated learning over time, spatiality arises for several reasons. Some these include the exchange of information between taxpayers; the social norm of tax compliance: an individual would comply if everybody in the society complies and vice versa; individuals faced with dynamic stochastic decision problems that pose immense computational challenges may simply look to others to infer satisfactory policies and interpersonal dependence works through learning by imitating rather than learning by doing. State-level annual per return evasion of individual income tax and related data were used to examine the above hypotheses and found supports for both of them in the individual income tax evasion in the United States.

Essay one develops and tests a revenue-maximizing tax structure model. This model represents one of the first attempts to evaluate and compare the responsiveness of various tax instruments to tax evasion within a tax revenue maximization framework. We use data from both the OECD and East African countries and estimation is via a seemingly unrelated regression model. The GDP share of agricultural income is used as an instrument to correct for the simultaneity between tax revenue shares and tax evasion. Our findings indicate that tax evasion increases the tax authority’s reliance on consumption taxes vis-à-vis taxes on income, suggesting that diverse tax instruments respond differently to tax evasion, and as such the choice of a revenue-maximizing tax structure is influenced by the amount of revenue lost through tax evasion. Essay two analyzes the incidence of tax evasion in both the formal and informal sectors of the economy using a computable general equilibrium model. This essay incorporates the element of uncertainty in an individual’s decision to evade so as to account for the uncertainty of returns to the tax evader. We also allow for varying degrees of competi¬tion or entry across sectors in the economy to examine how much of the tax advantage is retained by the initial evaders and how much is shifted via factor and commodity price changes. Our simulation results show that the evading households’ post-evasion welfare is only 0.68-3.40 percent higher than the post-tax welfare if it had fully complied with taxes. The simulation results further reveal that the evading household keeps 77.1-83.2 percent of this initial increase in welfare, while 16.8-22.9 percent of this initial gain is competed away as a result of increased competition and entry into the informal sector. The compliant households’ welfare increases by 58.8-101.7 percent with increased competition in the informal sector. Therefore, if we construe the changes in consumer welfare as an overall indicator of the gains and/or losses from tax evasion, then the evading household only benefits marginally and this advantage diminishes with increased entry or competition in the informal sector.

Graph searching problems are described as games played on graphs, between a set of searchers and a fugitive. Variants of the game restrict the abilities of the searchers and the fugitive and the corresponding search number (the least number of searchers that have a winning strategy) is related to several well-known parameters in graph theory. One popular variant is called the Cops and Robber game, where the searchers (cops) and the fugitive (robber) move in rounds, and in each round they move to an adjacent vertex. This game, defined in late 1970's, has been studied intensively. The most famous open problem is Meyniel's conjecture, which states that the cop number (the minimum number of cops that can always capture the robber) of a connected graph on n vertices is O(sqrt n). We consider a version of the Cops and Robber game, where the robber is faster than the cops, but is not allowed to jump over the cops. This version was first studied in 2008. We show that when the robber has speed s, the cop number of a connected n-vertex graph can be as large as Omega(n^(s/s+1)). This improves the Omega(n^(s-3/s-2)) lower bound of Frieze, Krivelevich, and Loh (Variations on Cops and Robbers, J. Graph Theory, to appear). We also conjecture a general upper bound O(n^(s/s+1)) for the cop number, generalizing Meyniel's conjecture. Then we focus on the version where the robber is infinitely fast, but is again not allowed to jump over the cops. We give a mathematical characterization for graphs with cop number one. For a graph with treewidth tw and maximum degree Delta, we prove the cop number is between (tw+1)/(Delta+1) and tw+1. Using this we show that the cop number of the m-dimensional hypercube is between c1 n / m sqrt(m) and c2 n / m for some constants c1 and c2. If G is a connected interval graph on n vertices, then we give a polynomial time 3-approximation algorithm for finding the cop number of G, and prove that the cop number is O(sqrt(n)). We prove that given n, there exists a connected chordal graph on n vertices with cop number Omega(n/log n). We show a lower bound for the cop numbers of expander graphs, and use this to prove that the random G(n,p) that is not very sparse, asymptotically almost surely has cop number between d1 / p and d2 log (np) / p for suitable constants d1 and d2. Moreover, we prove that a fixed-degree regular random graph with n vertices asymptotically almost surely has cop number Theta(n).

No description available.

Pursuit and evasion games have garnered much research attention since the class of problems was first posed over a half century ago. With wide applicability to both civilian and military problems, the study of pursuit and evasion games showed much early promise. Early work generally focused on analytical solutions to games involving a single pursuer and a single evader. These solutions generally assumed simple system dynamics to facilitate convergence to a solution. More recently, numerical techniques have been utilized to solve more difficult problems. While many sophisticated numerical tools exist for standard optimization and optimal control problems, developing a more complete set of numerical tools for pursuit and evasion games is still a developing topic of research. This thesis extends the current body of numeric solution tools in two ways. First, an existing approach that modifies sophisticated optimization tools to solve two player pursuer and evasion games is extended to incorporate a class of state inequality constraints. Several classical problems are solved to illustrate the e±cacy of the new approach. Second, a new cooperation metric is introduced into the system objective function for multi-player pursuit and evasion games. This new cooperation metric encourages multiple pursuers to surround and then proceed to capture an evader. Several examples are provided to demonstrate this new cooperation metric.

This dissertation comprises three chapters. The first chapter investigates whether consumers can help governments improve firm compliance with the Value Added Tax. It exploits quasi-experimental variation from a government program from Sao Paulo, Brazil that created monetary rewards for consumers to ask for receipts. To assess how incentives to consumers can be effective despite potential collusion opportunities, I construct datasets for 1 million firms, 40 million consumers, and 2.7 billion receipts. I estimate that revenue reported in retail increased by at least 22% over four years. The estimated compliance effect is stronger for sectors with a high volume of transactions and small receipt values, consistent with a model in which there are fixed costs to negotiate collusive deals to avoid issuing receipts. Furthermore, the effect has an inverted-U shape with respect to firm size. This result is consistent with a model of higher baseline compliance among larger firms, and in which shifts in audit probability from consumer monitoring increase in firm size. I find no effects on exit rates or formal employment decisions.

Issues and problems associated with the seriousness of tax non-compliance have increased dramatically over the years due to the widening tax gaps experienced by governments worldwide as a result of sophisticated transactions. To add to the severity of the situation are the concerns surrounding the difficulties associated with our abilities in defining what is meant by tax compliance, non-compliance and their relevant sub-categories. This study reviews both the international existing literature and New Zealand case law to examine how the concepts have (or have not) been defined over the years within particular studies and case law. The results are presented in the form of a critical literature review where the definitions (or descriptions) for the concepts are organized into tables, in order to compare how the definitions have (or have not) been ‘improved’ over the years. Lastly, this study discusses the implications regarding whether ‘universal’ definitions can or should be developed and attributed to each of the concepts in order to clear the murkiness between our understanding of the various concepts of tax compliance, non-compliance, and their sub-categories.

Graph searching problems are described as games played on graphs, between a set of searchers and a fugitive. Variants of the game restrict the abilities of the searchers and the fugitive and the corresponding search number (the least number of searchers that have a winning strategy) is related to several well-known parameters in graph theory. One popular variant is called the Cops and Robber game, where the searchers (cops) and the fugitive (robber) move in rounds, and in each round they move to an adjacent vertex. This game, defined in late 1970's, has been studied intensively. The most famous open problem is Meyniel's conjecture, which states that the cop number (the minimum number of cops that can always capture the robber) of a connected graph on n vertices is O(sqrt n). We consider a version of the Cops and Robber game, where the robber is faster than the cops, but is not allowed to jump over the cops. This version was first studied in 2008. We show that when the robber has speed s, the cop number of a connected n-vertex graph can be as large as Omega(n^(s/s+1)). This improves the Omega(n^(s-3/s-2)) lower bound of Frieze, Krivelevich, and Loh (Variations on Cops and Robbers, J. Graph Theory, to appear). We also conjecture a general upper bound O(n^(s/s+1)) for the cop number, generalizing Meyniel's conjecture. Then we focus on the version where the robber is infinitely fast, but is again not allowed to jump over the cops. We give a mathematical characterization for graphs with cop number one. For a graph with treewidth tw and maximum degree Delta, we prove the cop number is between (tw+1)/(Delta+1) and tw+1. Using this we show that the cop number of the m-dimensional hypercube is between c1 n / m sqrt(m) and c2 n / m for some constants c1 and c2. If G is a connected interval graph on n vertices, then we give a polynomial time 3-approximation algorithm for finding the cop number of G, and prove that the cop number is O(sqrt(n)). We prove that given n, there exists a connected chordal graph on n vertices with cop number Omega(n/log n). We show a lower bound for the cop numbers of expander graphs, and use this to prove that the random G(n,p) that is not very sparse, asymptotically almost surely has cop number between d1 / p and d2 log (np) / p for suitable constants d1 and d2. Moreover, we prove that a fixed-degree regular random graph with n vertices asymptotically almost surely has cop number Theta(n).