Web information retrieval is a relatively new research area that has attracted a significant amount of interest from researchers around the world since the emergence of the World Wide Web in the early 1990s. The problems facing successful web information retrieval are a combination of challenges that stem from traditional information retrieval and challenges characterised by the nature of the World Wide Web. The goal of any information retrieval system is to provide an information need fulfilment in response to an information need. In a web setting, this means retrieving as many relevant web documents as possible in response to an inputted query that is typically limited to only containing a few terms expressive of the user's information need. This thesis is primarily concerned with firstly reviewing pertinent literature related to various aspects of web information retrieval research and secondly proposing and investigating a novel concept and context-based approach. The approach consists of techniques that can be used together or independently and aim to provide an improvement in retrieval accuracy over other approaches. A novel concept-based term weighting technique is proposed as a new method of deriving query term significance from ontologies that can be used for the weighting of inputted queries. A technique that dynamically determines the significance of terms occurring in documents based on the matching of contexts is also proposed. Other contributions of this research include techniques for the combination of document and query term weights for the ranking of retrieved documents. All techniques were implemented and tested on benchmark data. This provides a basis for performing comparison with previous top performing web information retrieval systems. High retrieval accuracy is reported as a result of utilising the proposed approach. This is supported through comprehensive experimental evidence and favourable comparisons against previously published results.

Submitted by Kelson Anthony de Menezes (kelson@ucb.br) on 2017-01-09T11:10:46Z No. of bitstreams: 1 BrunaRibeiroGanemDissertacaoParcial2015.pdf: 952390 bytes, checksum: b9f45d5295e02005f556c040f27bb147 (MD5) / Made available in DSpace on 2017-01-09T11:10:46Z (GMT). No. of bitstreams: 1 BrunaRibeiroGanemDissertacaoParcial2015.pdf: 952390 bytes, checksum: b9f45d5295e02005f556c040f27bb147 (MD5) Previous issue date: 2015-12-15 / This is a critical paper about the incidence of Real State Tax, a municipal tax, in cases where immovable properties and assets held by Federal or States Government are occupied by particular persons, as result of legal use concession contracts or authorized occupation, and its connections with the Mutual Tax Immunity. To achieve these aims, therefore, this study solved the following research problems: in first place, confirmation of the partial unconstitutionality of the National Tax Code in relation to the Constitution of 1946 and its non reception by the current Federal Constitution (1988); construction of the normative matrix rule of the studied tax, since the constitutional level, passing throw the complementary legal settlement, until the local legislation, study that resulted in a doctrinal refinement of the analyzed institute, specially, on its material, personal e quantitative criterions; and, in second place, implications of the Mutual Tax Immunity on the definition of the taxpayer subject, considering the impossibility of transferring the payment responsibility to a non-taxable person, such as the occupant of the public property covered by a concession contract. Furthermore, this research analyzed the Mutual Tax Immunity under the Article 150, VI, ???a???, of the Federal Constitution, in order to identify if it grants a absolute status of protection against the taxation, or if it can be relaxed in cases where the Public Person explore remunerate economic activities. These subjects are under judgment by the Brazilian Supreme Court in the Leading Case number 473 of the general repercussion. Finally, from the theory of the fundamental rights of Robert Alexy, pondering and weighing were developed in order to solve the conflict between the involved constitutional principles: the Free Competition as a key element of an open market economy; and the Mutual Tax Immunity as a guarantor of the Federation Principle. / O objeto de estudo deste trabalho ?? a an??lise da incid??ncia do Imposto Predial e Territorial Urbano (IPTU) sobre os im??veis p??blicos ocupados por particulares por meio de contratos onerosos de concess??o de direito real de uso. No primeiro cap??tulo, a autora fez uma an??lise hist??ria da evolu????o constitucional do estudado imposto e suas rela????es com o C??digo Tribut??rio Nacional (CTN), que resultou no reconhecimento da inconstitucionalidade material de partes dos artigos 32 e 34 do CTN em face da Constitui????o de 1946, bem como a sua n??o recep????o parcial pela Constitui????o Federal de 1988. No cap??tulo subsequente, a norma tribut??ria do IPTU foi estruturada em seus diversos planos normativos, com a constru????o de suas regras-matrizes constitucional, complementar e local, cujos conte??dos se mostraram conflitantes. O terceiro cap??tulo foi direcionado para a constru????o de uma proposta de solu????o para o Tema 437 da Repercuss??o Geral do Supremo Tribunal Federal, que tem como objeto a verifica????o da possibilidade de manuten????o da imunidade tribut??ria rec??proca dos entes p??blicos nas situa????es em que transferem a posse e o uso de seus bens im??veis para particulares mediante o recebimento de contrapresta????o. Nesse contexto, foi necess??rio analisar se a imunidade em quest??o pode ser afastada em raz??o do car??ter oneroso do contrato, bem como se essa atividade de concess??o de bem im??vel p??blico pode ser considerada como h??bil para interferir na livre concorr??ncia do setor imobili??rio local. Para solucionar essas quest??es, utilizou-se a teoria dos direitos fundamentais de Robert Alexy, com a pondera????o e o sopesamento do princ??pio da imunidade tribut??ria rec??proca com o da livre concorr??ncia, a fim de verificar qual deles deve prevalecer no caso concreto. Por fim, foi apresentada uma proposta de solu????o para o leading case que tem a pretens??o tanto de harmonizar o conflito principiol??gico constatado, como de aprimorar a estrutura????o da regra-matriz do IPTU, particularmente no que tange ?? defini????o de seus crit??rios material, pessoal e quantitativo.