Optimizing and Implementing Repair Programs for Consistent Query Answering in Databases

Databases may not always satisfy their integrity constraints (ICs) and a number of different reasons can be held accountable for this. However, in most cases an important part of the data is still consistent with the ICs, and can still be retrieved through queries posed to the database. Consistent query answers are characterized as ordinary answers obtained from every minimally repaired and consistent version of the database. Database repairs wrt a wide class of ICs can be specified as stable models of disjunctive logic programs. Thus, Consistent Query Answering (CQA) for first-order queries is translated into cautious reasoning under the stable models semantics. The use of logic programs does not exceed the intrinsic complexity of CQA. However, using them in a straightforward manner is usually inefficient. The goal of this thesis is to develop optimized techniques to evaluate queries over inconsisten

Capacidade diagnóstica das escalas Braden Q e Norton para ulceres pressores em pacientes pediátricos de unidades críticas

The objective of the investigation was to evaluate the diagnostic capacity of the Braden Q and Norton scales for the development of pressure ulcers in pediatric patients of Critical Units in a highly complex hospital in Chile. It is a cross-sectional study comparing diagnostic tests in patients admitted to critical units. The sample was non-probabilistic, for the convenience of 118 children. Both scales were analyzed respecting the precepts, in order to compare the discriminative capacity of two diagnostic tests verifying that both are measured simultaneously while applied on the same subjects. The research was approved by the Ethics Committee, Health Service and Informed Consent signed by the parents of the children. It was determined that the sensitivity of the Braden Q scale, at 24 and 48 hours, is lower than Norton´s in the same evaluations; it has a higher positive predictive value in both measurements, as well as the probability ratio (+). It is concluded that Braden Q is the ideal scale to assess the risk of developing pressure ulcers in the pediatric population; it presents greater reliability.El objetivo de la investigación fue conocer la capacidad diagnóstica de las escalas Braden Q y Norton para el desarrollo de úlceras por presión en pacientes pediátricos de Unidades Críticas en un hospital de alta complejidad en Chile. Es un estudio transversal de comparación de pruebas diagnósticas en pacientes ingresados a unidades críticas. La muestra fue no probabilística, por conveniencia de 118 niños. Se analizaron ambas escalas respetando los preceptos, para comparar la capacidad discriminativa de dos pruebas diagnósticas y verificar que ambas sean medidos simultáneamente aplicadas sobre los mismos sujetos. La investigación contó con aprobación de comité de Ética Servicio de Salud y Consentimiento Informado firmado de los padres de los niños. Se determinó que la sensibilidad de la escala Braden Q, a las 24 y 48 horas, es menor que la presentada por la Norton en las mismas evaluaciones; presenta valor predictivo positivo más alto en ambas mediciones, como también la razón de probabilidad (+). Se concluye que Braden Q es la escala idónea para valorar el riesgo de desarrollar UPP en la población pediátrica; presenta mayor confiabilidad.O objetivo da investigação foi conhecer a capacidade diagnóstica das escalas Braden Q e Norton, para o desenvolvimento de úlceras de pressão (UPP) em pacientes pediátricos de unidades críticas, em um hospital altamente complexo, no Chile. É um estudo transversal que compara testes diagnósticos em pacientes admitidos em unidades críticas. A amostra não era probabilística, para a conveniência de 118 crianças. Ambas as escalas foram analisadas respeitando os preceitos, para comparar a capacidade discriminativa de dois testes de diagnóstico e verificar que ambos são medidos simultaneamente, aplicados nos mesmos assuntos. A pesquisa foi aprovada pelo Comitê de Ética, Serviço de Saúde e Consentimento Informado assinado por pais de crianças. Determinou-se que a sensibilidade da escala de Braden Q, às 24 e 48 horas, é menor que a apResentada por Norton nas mesmas avaliações, possui maior valor preditivo positivo em ambas as medidas, bem como a razão de probabilidade (+). Conclui-se que Braden Q é a escala ideal para avaliar o risco de desenvolver UPP na população pediátrica, e apresenta maior confiabilidade

Handling Inconsistencies in Data Warehouses

Abstract. Data warehouses (DWs) can become inconsistent when some dimensional constraints are not satisfied by the dimension instances. In this paper, we present preliminary results about the effects of the violation of partitioning constraints in homogeneous dimension instances over aggregation queries, and in particular over the summarizability property (SUMM) of the DWs. We are interested in finding ways to retrieve consistent answers even when the DW is inconsistent. We give a notion of repair for inconsistent instances based on a notion of prioritized minimization. We also describe a notion of consistent answer in DWs.

The Consistency Extractor System: Answer Set Programs for Consistent Query Answering in Databases

We describe the Consistency Extractor System (ConsEx) that computes consistent answers to Datalog queries with negation posed to relational databases that may be inconsistent with respect to certain integrity constraints. In order to solve this task, ConsEx uses answers set programming. More precisely, ConsEx uses disjunctive logic programs with stable models semantics to specify and reason with the repairs, i.e. with the consistent virtual instances that minimally depart from the original database. The consistent information is invariant under all repairs. ConsEx achieves efficient query evaluation by implementing magic sets techniques. We describe the general methodology, its optimizations for query answering, and the architecture of the system. We also present encouraging experimental results