The Complexity of Resilience

One focus area in data management research is to understand how changes in the data can affect the output of a view or standing query. Example applications are explaining query results and propagating updates through views. In this thesis we study the complexity of the Resilience problem, which is the problem of finding the minimum number of tuples that need to be deleted from the database in order to change the result of a query. We will see that resilience is closely related to the well-studied problems of deletion propagation and causal responsibility, and that analyzing its complexity offers important insight for solving those problems as well. Our contributions include the definition of the concept of triads for conjunctive queries, which is a crucial tool on our analysis, and the characterization of a NP versus P dichotomy for the resilience problem considering the class of conjunctive queries without self-joins. Moreover, this result allowed us to show dichotomies for the same class of queries for both deletion propagation with source side-effects and causal responsibility problems. We also completely characterize how the presence of functional dependencies can change the complexity of such problems. The class of conjunctive queries with self-joins is far richer and more complicated than the self-join-free ones. Therefore we focus on binary queries without variable repetition, which are queries formed by unary or binary relations only and each atom has only one occurrence of any variable. For this restricted case, we identify three main query structures that help us identify complexity: chains, permutations and confluences. Using those we are able to characterize classes of queries for which resilience is NP-complete and some for which it is P

The Descriptive Complexity of the Deterministic Exponential Time Hierarchy

AbstractIn Descriptive Complexity, we investigate the use of logics to characterize computational complexity classes. Since 1974, when Fagin proved that the class NP is captured by existential second-order logic, considered the first result in this area, other relations between logics and complexity classes have been established. Well-known results usually involve first-order logic and its extensions, and complexity classes in polynomial time or space. Some examples are that the first-order logic extended by the least fixed-point operator captures the class P and the second-order logic extended by the transitive closure operator captures the class PSPACE. In this paper, we will analyze the combined use of higher-order logics of order i, HOi, for i⩾2, extended by the least fixed-point operator, and we will prove that each level of this hierarchy captures each level of the deterministic exponential time hierarchy. As a corollary, we will prove that the hierarchy of HOi(LFP), for i⩾2, does not collapse, that is, HOi(LFP)⊂HOi+1(LFP)

Lesão Pulmonar Associada Ao Uso De Cigarros Eletrônicos: Revisão De Literatura

E-cigarettes, a widely used emerging product, are facing growing popularity despite little research into their health risks. Electronic Cigarette Use Associated Lung Injury, or EVALI, has become a prominent concern in recent research, expanding the need to understand the health effects of vaping, given the diversity of technologies and liquids involved. An integrative review was carried out to analyze the relationship between electronic cigarettes and lung injuries, using the PubMed database. 664 articles were selected, with inclusion criteria based on human studies published between 2018 and 2023. The analysis, exclusion and selection process was carefully conducted by the authors. Electronic cigarettes, consisting of a battery, atomizer and liquid, stand out due to the uncertainty about their health effects, in contrast to traditional cigarettes. EVALI, predominantly associated with the vaporization of THC products, reveals serious symptoms and significant risks. The complex composition of e-liquids, especially when exposed to high temperatures, generates harmful substances, including carbonyl compounds, suspected of causing oxidative stress and inflammation in the airways. The integrative review highlights the lack of consensus on the safety of electronic cigarettes and the urgency in understanding the associated risks. EVALI, as a diagnosis of exclusion, highlights the need for immediate investigation in the event of respiratory symptoms. Treatment and monitoring of EVALI patients requires a careful approach, considering clinical and risk factors. Public education about potential dangers and cessation strategies becomes crucial, especially among young people.Los cigarrillos electrónicos, un producto emergente ampliamente utilizado, se enfrentan a una creciente popularidad a pesar de la poca investigación sobre sus riesgos para la salud. La lesión pulmonar asociada al uso de cigarrillos electrónicos, o EVALI, se ha convertido en una preocupación destacada en investigaciones recientes, ampliando la necesidad de comprender los efectos del vapeo en la salud, dada la diversidad de tecnologías y líquidos involucrados. Se realizó una revisión integradora para analizar la relación entre los cigarrillos electrónicos y las lesiones pulmonares, utilizando la base de datos PubMed. Se seleccionaron 664 artículos, con criterios de inclusión basados ​​en estudios en humanos publicados entre 2018 y 2023. El proceso de análisis, exclusión y selección fue cuidadosamente realizado por los autores. Los cigarrillos electrónicos, compuestos por batería, atomizador y líquido, destacan por la incertidumbre sobre sus efectos sobre la salud, a diferencia de los cigarrillos tradicionales. EVALI, predominantemente asociado con la vaporización de productos de THC, revela síntomas graves y riesgos importantes. La compleja composición de los e-líquidos, especialmente cuando se exponen a altas temperaturas, genera sustancias nocivas, incluidos compuestos carbonílicos, sospechosos de causar estrés oxidativo e inflamación en las vías respiratorias. La revisión integradora destaca la falta de consenso sobre la seguridad de los cigarrillos electrónicos y la urgencia de comprender los riesgos asociados. EVALI, como diagnóstico de exclusión, destaca la necesidad de investigación inmediata en caso de síntomas respiratorios. El tratamiento y seguimiento de los pacientes con EVALI requiere un enfoque cuidadoso, considerando los factores clínicos y de riesgo. La educación pública sobre los peligros potenciales y las estrategias para dejar de fumar se vuelve crucial, especialmente entre los jóvenes.Os cigarros eletrônicos, produto emergente amplamente utilizado, enfrentam crescente popularidade apesar da escassa investigação sobre seus riscos à saúde. A Lesão Pulmonar Associada ao Uso de Cigarro Eletrônico, ou EVALI, tornou-se uma preocupação destacada nas pesquisas recentes, ampliando a necessidade de compreender os efeitos da vaporização na saúde, dada a diversidade de tecnologias e líquidos envolvidos. Realizou-se uma revisão integrativa para analisar a relação entre cigarros eletrônicos e lesões pulmonares, utilizando a base de dados PubMed. Foram selecionados 664 artigos, com critérios de inclusão baseados em estudos humanos publicados entre 2018 e 2023. O processo de análise, exclusão e seleção foi conduzido de forma criteriosa pelos autores. Os cigarros eletrônicos, compostos por bateria, atomizador e líquido, destacam-se pela incerteza sobre seus efeitos à saúde, em contraste com os tradicionais. A EVALI, predominantemente associada à vaporização de produtos com THC, revela sintomas graves e riscos significativos. A composição complexa dos e-líquidos, especialmente quando expostos a altas temperaturas, gera substâncias nocivas, incluindo compostos carbonílicos, suspeitos de causar estresse oxidativo e inflamação nas vias aéreas. A revisão integrativa destaca a falta de consenso sobre a segurança dos cigarros eletrônicos e a urgência em compreender os riscos associados. A EVALI, como diagnóstico de exclusão, destaca a necessidade de investigação imediata diante de sintomas respiratórios. O tratamento e o acompanhamento de pacientes EVALI requerem abordagem cuidadosa, considerando fatores clínicos e de risco. A educação pública sobre os perigos potenciais e estratégias de cessação torna-se crucial, especialmente entre os jovens

Descriptive complexity of the logic of higher order with lower fixed point and analysis of expression of some modal logics

Em Complexidade Descritiva investigamos o uso de logicas para caracterizar classes problemas pelo vies da complexidade. Desde 1974, quando Fagin provou que NP e capturado pela logica existencial de segunda-ordem, considerado o primeiro resultado da area, outras relac~oes entre logicas e classes de complexidade foram estabelecidas. Os resultados mais conhecidos normalmemte envolvem logica de primeira-ordem e suas extens~oes, e classes de complexidade polinomiais em tempo ou espaco. Alguns exemplos sÃo que a logica de primeira-ordem estendida com o operador de menor ponto xo captura a clsse P e que a logica de segunda-ordem estendida com o operador de fecho transitivo captura a classe PSPACE. Nesta dissertaÃÃo, analisaremos inicialmente a expressividade de algumas logicas modais com relacÃo ao problema de decisÃo REACH e veremos que e possvel expressa-lo com as logicas temporais CTL e CTL. Analisaremos tambem o uso combinado de logicas de ordem superior com o operador de menor ponto xo e obteremos como resultado que cada nvel dessa hierarquia captura cada nvel da hierarquia determinstica em tempo exponencial. Como corolario, provamos que a hierarquia de HOi(LFP) nÃo colapsa, ou seja, HOi(LFP) HOi+1(LFP)In Descriptive Complexity, we investigate the use of logics to characterize computational classes os problems through complexity. Since 1974, when Fagin proved that the class NP is captured by existential second-order logic, considered the rst result in this area, other relations between logics and complexity classes have been established. Wellknown results usually involve rst-order logic and its extensions, and complexity classes in polynomial time or space. Some examples are that the rst-order logic extended by the least xed-point operator captures the class P and the second-order logic extended by the transitive closure operator captures the class PSPACE. In this dissertation, we will initially analyze the expressive power of some modal logics with respect to the decision problem REACH and see that is possible to express it with temporal logics CTL and CTL. We will also analyze the combined use of higher-order logics extended by the least xed-point operator and obtain as result that each level of this hierarchy captures each level of the deterministic exponential time hierarchy. As a corollary, we will prove that the hierarchy of HOi(LFP), for i 2, does not collapse, that is, HOi(LFP) HOi+1(LFP