Th. univ.--Mathématiques mention informatique--Paris VI, 1987. / 1987 d'après la déclaration de dépôt légal. Bibliogr. p. 213-219.

Th.--Sci. math.--Paris 11--Orsay, 1981. N°: 2522.

Supervisor : Professor Ross Stewart In the last decade there has been considerable interest in strongly basic solutions and Hammett H_ acidity functions have been defined for various solvent systems. However some doubts still remain about the ionization modes of certain indicators which were used to determine these H_ functions, and the pKa values assigned to weak carbon acids. A careful anchoring of the H_ scale for the system dimethylsulfoxide-water-0.011 molar tetramethylammonium hydroxide with 2,4,4'-trinitrodiphenylamine was undertaken. The lower region of this scale correlates well with the recently published H_ function for the more basic regions. To study the dependence of H_ functions on indicator structure, the ionization of nitrogen and oxygen acids were compared in strongly basic systems. The solvent systems used in the study were dimethylsulfoxide-methanol-0.01 molar sodium methoxide and dimethylsulfoxide-ethanol-0.01 molar sodium ethoxide. The shallow rise of the function for phenols as compared to that of the HN for diphenylamine is believed to be caused by the smaller degree of charge delocalization in the phenolate anions than in the amide ions. The dissociation constants of 15 substituted nitrodiphenyl-amines were determined in the two previously mentioned alcoholic dimethylsulfoxide systems, and in the aqueous dimethylsulfoxide system. The "similar colour indicator" postulate was elaborated on the observation that the relative acidity of Hammett-type indicators remains constant through changes in solvent environment only if their spectral characteristics are similar. Linear free energy relationships between the pK values of 30 substituted diphenylamines and the substituent constant, σ°, were drawn. The ρ value in excess of 4 for monosubstituted diphenylamines compared with ρ values of the order of 2 for nitrosubstituted diphenylamines, results from the low degree of conjugation between the central N atom and the ring substituent whenever a nitro group is present in the other ring. The base-catalyzed rates of detritiation of various hydrocarbons were determined in dimethylsulfoxide mixtures. The logarithm of these rates were correlated with the thermodynamic basicity of the medium as measured by the H N function and gave excellent straight lines with slopes around 0.8. The theoretical basis of such correlations is discussed, and it was concluded that the logarithm of the rates should be correlated with H_ + log aROH. In the case of methanolic dimethylsulfoxide the activity of methanol has been determined, giving corrected correlations with slopes around 0.9. The qualitative limitation due to the use of HN instead of HC functions is also discussed. The activation parameters for these detritiations have been determined. The enthalpies of activation were found to increase with decreasing acidity of the hydrocarbon. These variations in enthalpy of activation, coupled with variation in the kinetic isotope effect and the observed Bronsted relationship have been interpreted in terms of a mechanism involving a rate-determining pre-equilibrium step with a transition state of increasing asymmetry. A critical examination of the HC scale for carbon acids in dimethylsulfoxide-ethanol-0.01 molar sodium ethoxide was made. The failure of the scale probably results from the fact that, for a number of indicators, proton abstraction is followed by a reaction between the carbanion and the neutral molecule to give a radical and radical anion. The carbanions of three nitrophenylmethanes were prepared in hexamethylphosphoramide and unequivocally identified by high resolution nuclear magnetic resonance. The spectral characteristics of the carbanions were recorded and compared with previously published values. The radical anions of these nitrophenylmethanes were generated electrochemically and their e.s.r. spectra measured. The variation in ¹⁴N hyperfine coupling constant (aN) of these radical anions indicated a large solvent shift in the absorption maxima. / Science, Faculty of / Chemistry, Department of / Graduate

Doctor en Ciencias, Mención Computación / Las bases de datos de grafos han recibido mucho interés en los últimos años, debido a sus aplicaciones en temas como las redes sociales o la Web Semántica. En esta tesis estudiamos lenguajes de consultas que poseen las características navegaciones fundamentales para las distintas aplicaciones de bases de datos de grafos. Estos incluyen la clase de consultas regulares de caminos (RPQs), las cuales chequean si dos nodos están conectados por un camino cuya etiqueta satisface una expresión regular; la clase de las RPQs con inversos (2RPQs), que adicionalmente permiten navegar arcos en la dirección reversa; la clase de las uniones de conjunciones de 2RPQs (UC2RPQs), que resulta de cerrar las 2RPQs bajo las operaciones de join, projección y unión; y la clase de las consultas regulares (RQs) que adicionalmente cierra las UC2RPQs bajo clausura transitiva. En esta tesis demostramos nuevos resultados de complejidad para UC2RPQs y RQs. En la primera parte, estudiamos evaluación de UC2RPQs. Este problema es computacionalmente difícil: NP-completo en general y W[1]-completo en complejidad parametrizada. Esto ha motivado la búsqueda de restricciones que hacen que la evaluación sea tratable o tratable de parámetro fijo. Las más importantes son las clases de UC2RPQs de treewidth acotado, que se pueden evaluar en tiempo polinomial, pero hasta la fecha no se conocen otras restricciones que sean tratables o tratables de parámetro fijo. El resultado principal de esta parte es que la evaluación de UC2RPQs de treewidth acotado módulo equivalencia es tratable de parámetro fijo. Más precisamente, demostramos que, para cada k fijo, existe un algoritmo tratable de parámetro fijo que evalúa UC2RPQs que son equivalentes a alguna UC2RPQ de treewidth a lo más k. También estudiamos el caso cuando la cota k es 1, esto es, la clase de UC2RPQs semánticamente acíclicas, y obtenemos aún más resultados. En particular, demostramos que chequear acaso una UC2RPQ es semánticamente acíclica es decidible y EXPSPACE-completo. En la segunda parte, estudiamos contención de RQs. Las RQs han emergido recientemente como un lenguaje natural para bases de datos de grafos. Las RQs tienen propiedades naturales de clausura, no como las UC2RPQs que no son cerradas bajo clausura transitiva. Además, evaluar RQs no es más difícil que evaluar UC2RPQs (NP-completo). Sin embargo, el problema de contención de RQs aún está abierto. Este problema es decidible, pero sólo cotas no elementales son conocidas. En contraste, es sabido que contención de UC2RPQs es elemental, específicamente, EXPSPACE-completo. El resultado principal de esta parte es que contención de RQs es 2EXPSPACE-completo, y luego, tiene complejidad elemental tal como las UC2RPQs. También estudiamos restricciones de RQs que mejoran la complejidad de evaluación o contención, y algunas extensiones. En particular, demostramos que contención para una generalización natural de RQs para bases de datos relacionales es 2EXPSPACE-completo. / Graph databases have gained renewed interest in recent years, due to their application in areas such as social networks and the Semantic Web. We study graph query languages that provide the fundamental navigational features needed in di erent graph database applications. This includes the class of regular path queries (or RPQs for short), which check whether two nodes are connected by a path whose label satis es a regular expression; the class of two-way RPQs (2RPQs), which additionally enables backward navigation of edges; the class of unions of conjunctive 2RPQs (UC2RPQs), which results from closing 2RPQs under the operations of join, projection, and union; and the class of regular queries (RQs), which additionally closes UC2RPQs under transitive closure. In this thesis, we provide new complexity results for UC2RPQs and RQs. In the rst part, we study query evaluation for UC2RPQs. This problem is known to be computationally hard: NP-complete in combined complexity and W[1]-complete in parameterized complexity. This has motivated the search for restrictions that lead to ( xed-parameter) tractable evaluation. The most prominent restrictions are the classes of UC2RPQs of bounded treewidth, which can be evaluated in polynomial time, but no other tractable or xed-parameter tractable restrictions are known to date. Our main result in this part is that evaluation for UC2RPQs of bounded treewidth modulo equivalence is xed-parameter tractable. More precisely, we show that, for each xed k 1, there is a xed-parameter tractable algorithm that evaluates UC2RPQs that are equivalent to some UC2RPQ of treewidth at most k. We also study the case when the bound k equals 1, that is, the class of semantically acyclic UC2RPQs, and provide further results. In particular, we show that checking whether a UC2RPQ is semantically acyclic is decidable and Expspace-complete. In the second part, we study query containment for RQs. The class of RQs has emerged only recently as a natural graph query language. RQs have natural closure properties, unlike UC2RPQs that are not closed under transitive closure. Moreover, RQs are not harder to evaluate than UC2RPQs (NP-complete). Nevertheless, the containment problem for RQs has been open so far. This problem is decidable, but only nonelementary complexity upper bounds are known. In contrast, query containment for UC2RPQs is known to be elementary, speci cally, Expspace-complete. Our main result in this part is that containment of RQs is 2Expspace-complete, and therefore, it has elementary complexity just like UC2RPQs. We also study restrictions of RQs that help to alleviate the complexity of evaluation or containment, and also some extensions. In particular, we show that containment of a natural generalization of RQs for relational databases is still 2Expspace-complete. / Este trabajo ha sido financiado por Conicyt y el Centro de Investigación de la Web Semántica

Thesis (Ph. D.)--Washington State University, May 2010. / Title from PDF title page (viewed on June 4, 2010). "Edward R. Murrow College of Communication." Includes bibliographical references (p. 110-126).

El alcance del presente proyecto de fin de carrera el análisis y diseño de los procesos que componen el conjunto de ITIL como son: La Gestión de Configuraciones y La Gestión de Cambios; elaborada para el área de TI de la empresa importadora y distribuidora de vidrios y aluminios. El presente proyecto tiene como finalidad establecer una guía de buenas prácticas en el área de TI, la cual pueda ser consultada al realizarse las tareas que involucran los procesos de gestión de configuraciones y gestión de cambios. La presente propuesta está dirigida a todas las organizaciones y/o empresas que manejen recursos de TI. Por lo tanto, las recomendaciones o buenas prácticas tratarán de ser las más genéricas posibles para poder apartase fácilmente a cualquier ambiente. Todos los requerimientos serán tomados de ITIL v3 ya que este constituye un marco de trabajo de las mejores prácticas destinadas a facilitar la entrega de servicios de tecnologías de la información (TI) de alta calidad. Cabe resaltar que no se realizará la implantación de un sistema propiamente dicho en el presente proyecto de fin de carrera dado el tiempo limitado que se tiene para realizar el proyecto y la resistencia al cambio de parte de la gerencia general de la empresa. / Tesis

No description available.

Texte remanié de: Dissertation--Freiburg im Breisgau--Albert-Ludwig-Universität, 2001.

Thèse doctorat : Informatique. Documents multimédia, Images et Systèmes d'Information Communicants : Villeurbanne, INSA : 2001. / Titre provenant de l'écran-titre. Bibliogr. p. 263-276.

Reproduction de : Thèse d'Etat : mathématiques : Grenoble 1 : 1986. / Titre provenant de l'écran-titre. Bibliogr. p. 187-197.