We investigate the expressive power of different fragments of higher-order logics over finite relational structures (or equivalently, relational databases) with special emphasis in higher-order logics of order greater than or equal three. Our main results concern the study of the effect on the expressive power of higher-order logics, of simultaneously bounding the arity of the higher-order variables and the alternation of quantifiers. Let AAi(r,m) be the class of (i + 1)-th order logic formulae where all quantifiers are grouped together at the beginning of the formulae, forming m alternating blocks of consecutive existential and universal quantifiers, and such that the maximal-arity (a generalization of the concept of arity, not just the maximal of the arities of the quantified variables) of the higher-order variables is bounded by r. Note that, the order of the quantifiers in the prefix may be mixed. We show that, for every i [greater than or equal to] 1, the resulting AAi hierarchy of formulae of (i + 1)-th order logic is proper. This extends a result by Makowsky and Pnueli who proved that the same hierarchy in second-order logic is proper. In both cases the strategy used to prove the results consists in considering the set AUTOSAT(F) of formulae in a given logic F which, represented as finite structures, satisfy themselves. We then use a similar strategy to prove that the classes of [Sigma superscript i subscript m union Pi superscript i subscript m] formulae in which the higher-order variables of all orders up to i+1 have maximal-arity at most r, also induce a proper hierarchy in each higher-order logic of order i [greater than or equal to] 3. It is not known whether the correspondent hierarchy in second-order logic is proper. Using the concept of finite model truth definitions introduced by M. Mostowski, we give a sufficient condition for that to be the case. We also study the complexity of the set AUTOSAT(F) and show that when F is one of the prenex fragments [Sigma superscript 1 subscript m] of second-order logic, it follows that AUTOSAT(F) becomes a complete problem for the corresponding prenex fragment [Sigma superscript 2 subscript m] of third-order logic. Finally, aiming to provide the background for a future line of research in higher-order logics, we take a closer look to the restricted second-order logic SO[superscript w] introduced by Dawar. We further investigate its connection with the concept of relational complexity studied by Abiteboul, Vardi and Vianu. Dawar showed that the existential fragment of SO[superscript w] is equivalent to the nondeterministic inflationary fixed-point logic NFP. Since NFP captures relational NP, it follows that the existential fragment of SO[superscript w] captures relational NP. We give a direct proof, in the style of the proof of Fagin’s theorem, of this fact. We then define formally the concept of relational machine with relational oracle and prove the exact correspondence between the prenex fragments of SO[superscript w] and the levels of the relational polynomial-time hierarchy. This allows us to stablish a direct connection between the relational polynomial hierarchy and SO without using the Abiteboul and Vianu normal form for relational machines.

We investigate the expressive power of different fragments of higher-order logics over finite relational structures (or equivalently, relational databases) with special emphasis in higher-order logics of order greater than or equal three. Our main results concern the study of the effect on the expressive power of higher-order logics, of simultaneously bounding the arity of the higher-order variables and the alternation of quantifiers. Let AAi(r,m) be the class of (i + 1)-th order logic formulae where all quantifiers are grouped together at the beginning of the formulae, forming m alternating blocks of consecutive existential and universal quantifiers, and such that the maximal-arity (a generalization of the concept of arity, not just the maximal of the arities of the quantified variables) of the higher-order variables is bounded by r. Note that, the order of the quantifiers in the prefix may be mixed. We show that, for every i [greater than or equal to] 1, the resulting AAi hierarchy of formulae of (i + 1)-th order logic is proper. This extends a result by Makowsky and Pnueli who proved that the same hierarchy in second-order logic is proper. In both cases the strategy used to prove the results consists in considering the set AUTOSAT(F) of formulae in a given logic F which, represented as finite structures, satisfy themselves. We then use a similar strategy to prove that the classes of [Sigma superscript i subscript m union Pi superscript i subscript m] formulae in which the higher-order variables of all orders up to i+1 have maximal-arity at most r, also induce a proper hierarchy in each higher-order logic of order i [greater than or equal to] 3. It is not known whether the correspondent hierarchy in second-order logic is proper. Using the concept of finite model truth definitions introduced by M. Mostowski, we give a sufficient condition for that to be the case. We also study the complexity of the set AUTOSAT(F) and show that when F is one of the prenex fragments [Sigma superscript 1 subscript m] of second-order logic, it follows that AUTOSAT(F) becomes a complete problem for the corresponding prenex fragment [Sigma superscript 2 subscript m] of third-order logic. Finally, aiming to provide the background for a future line of research in higher-order logics, we take a closer look to the restricted second-order logic SO[superscript w] introduced by Dawar. We further investigate its connection with the concept of relational complexity studied by Abiteboul, Vardi and Vianu. Dawar showed that the existential fragment of SO[superscript w] is equivalent to the nondeterministic inflationary fixed-point logic NFP. Since NFP captures relational NP, it follows that the existential fragment of SO[superscript w] captures relational NP. We give a direct proof, in the style of the proof of Fagin’s theorem, of this fact. We then define formally the concept of relational machine with relational oracle and prove the exact correspondence between the prenex fragments of SO[superscript w] and the levels of the relational polynomial-time hierarchy. This allows us to stablish a direct connection between the relational polynomial hierarchy and SO without using the Abiteboul and Vianu normal form for relational machines.

We investigate the expressive power of different fragments of higher-order logics over finite relational structures (or equivalently, relational databases) with special emphasis in higher-order logics of order greater than or equal three. Our main results concern the study of the effect on the expressive power of higher-order logics, of simultaneously bounding the arity of the higher-order variables and the alternation of quantifiers. Let AAi(r,m) be the class of (i + 1)-th order logic formulae where all quantifiers are grouped together at the beginning of the formulae, forming m alternating blocks of consecutive existential and universal quantifiers, and such that the maximal-arity (a generalization of the concept of arity, not just the maximal of the arities of the quantified variables) of the higher-order variables is bounded by r. Note that, the order of the quantifiers in the prefix may be mixed. We show that, for every i [greater than or equal to] 1, the resulting AAi hierarchy of formulae of (i + 1)-th order logic is proper. This extends a result by Makowsky and Pnueli who proved that the same hierarchy in second-order logic is proper. In both cases the strategy used to prove the results consists in considering the set AUTOSAT(F) of formulae in a given logic F which, represented as finite structures, satisfy themselves. We then use a similar strategy to prove that the classes of [Sigma superscript i subscript m union Pi superscript i subscript m] formulae in which the higher-order variables of all orders up to i+1 have maximal-arity at most r, also induce a proper hierarchy in each higher-order logic of order i [greater than or equal to] 3. It is not known whether the correspondent hierarchy in second-order logic is proper. Using the concept of finite model truth definitions introduced by M. Mostowski, we give a sufficient condition for that to be the case. We also study the complexity of the set AUTOSAT(F) and show that when F is one of the prenex fragments [Sigma superscript 1 subscript m] of second-order logic, it follows that AUTOSAT(F) becomes a complete problem for the corresponding prenex fragment [Sigma superscript 2 subscript m] of third-order logic. Finally, aiming to provide the background for a future line of research in higher-order logics, we take a closer look to the restricted second-order logic SO[superscript w] introduced by Dawar. We further investigate its connection with the concept of relational complexity studied by Abiteboul, Vardi and Vianu. Dawar showed that the existential fragment of SO[superscript w] is equivalent to the nondeterministic inflationary fixed-point logic NFP. Since NFP captures relational NP, it follows that the existential fragment of SO[superscript w] captures relational NP. We give a direct proof, in the style of the proof of Fagin’s theorem, of this fact. We then define formally the concept of relational machine with relational oracle and prove the exact correspondence between the prenex fragments of SO[superscript w] and the levels of the relational polynomial-time hierarchy. This allows us to stablish a direct connection between the relational polynomial hierarchy and SO without using the Abiteboul and Vianu normal form for relational machines.

We investigate the expressive power of different fragments of higher-order logics over finite relational structures (or equivalently, relational databases) with special emphasis in higher-order logics of order greater than or equal three. Our main results concern the study of the effect on the expressive power of higher-order logics, of simultaneously bounding the arity of the higher-order variables and the alternation of quantifiers. Let AAi(r,m) be the class of (i + 1)-th order logic formulae where all quantifiers are grouped together at the beginning of the formulae, forming m alternating blocks of consecutive existential and universal quantifiers, and such that the maximal-arity (a generalization of the concept of arity, not just the maximal of the arities of the quantified variables) of the higher-order variables is bounded by r. Note that, the order of the quantifiers in the prefix may be mixed. We show that, for every i [greater than or equal to] 1, the resulting AAi hierarchy of formulae of (i + 1)-th order logic is proper. This extends a result by Makowsky and Pnueli who proved that the same hierarchy in second-order logic is proper. In both cases the strategy used to prove the results consists in considering the set AUTOSAT(F) of formulae in a given logic F which, represented as finite structures, satisfy themselves. We then use a similar strategy to prove that the classes of [Sigma superscript i subscript m union Pi superscript i subscript m] formulae in which the higher-order variables of all orders up to i+1 have maximal-arity at most r, also induce a proper hierarchy in each higher-order logic of order i [greater than or equal to] 3. It is not known whether the correspondent hierarchy in second-order logic is proper. Using the concept of finite model truth definitions introduced by M. Mostowski, we give a sufficient condition for that to be the case. We also study the complexity of the set AUTOSAT(F) and show that when F is one of the prenex fragments [Sigma superscript 1 subscript m] of second-order logic, it follows that AUTOSAT(F) becomes a complete problem for the corresponding prenex fragment [Sigma superscript 2 subscript m] of third-order logic. Finally, aiming to provide the background for a future line of research in higher-order logics, we take a closer look to the restricted second-order logic SO[superscript w] introduced by Dawar. We further investigate its connection with the concept of relational complexity studied by Abiteboul, Vardi and Vianu. Dawar showed that the existential fragment of SO[superscript w] is equivalent to the nondeterministic inflationary fixed-point logic NFP. Since NFP captures relational NP, it follows that the existential fragment of SO[superscript w] captures relational NP. We give a direct proof, in the style of the proof of Fagin’s theorem, of this fact. We then define formally the concept of relational machine with relational oracle and prove the exact correspondence between the prenex fragments of SO[superscript w] and the levels of the relational polynomial-time hierarchy. This allows us to stablish a direct connection between the relational polynomial hierarchy and SO without using the Abiteboul and Vianu normal form for relational machines.

Zugl.: Lübeck, Univ., Diss., 2006

La croissance continue des besoins en puissance de calcul a conduit au triomphe du modèle de Cloud Computing. Des clients demandeurs en puissance de calcul vont s’approvisionner auprès de fournisseurs d’infrastructures de Cloud Computing, mises à disposition via Internet. Pour réaliser des économies d’échelles, ces infrastructures sont toujours plus grandes et concentrées en quelques endroits, conduisant à des problèmes tels que l’approvisionnement en énergie, la tolérance aux pannes et l’éloignement des utilisateurs. Cette thèse s’est intéressée à la mise en place d’un système d’IaaS massivement distribué et décentralisé exploitant un réseau de micros centres de données déployés sur la dorsale Internet, utilisant une version d’OpenStack revisitée pendant cette thèse autour du support non intrusif de bases de données non relationnelles. Des expériences sur Grid’5000 ont montré des résultats intéressants sur le plan des performances, toutefois limités par le fait qu’OpenStack ne tirait pas avantage nativement d’un fonctionnement géographiquement réparti. Nous avons étudié la prise en compte de la localité réseau pour améliorer les performances des services distribués en favorisant les collaborations proches. Un prototype de l’algorithme de placement de machines virtuelles DVMS, fonctionnant sur une topologie non structurée basée sur l’algorithme Vivaldi, a été validé sur Grid’5000. Ce prototype a fait l’objet d’un prix scientifique lors de l’école de printemps Grid’50002014. Enfin, ces travaux nous ont amenés à participer au développement du simulateur VMPlaceS. / The continuous increase of computing power needs has favored the triumph of the Cloud Computing model. Customers asking for computing power will receive supplies via Internet resources hosted by providers of Cloud Computing infrastructures. To make economies of scale, Cloud Computing that are increasingly large and concentrated in few attractive places, leading to problems such energy supply, fault tolerance and the fact that these infrastructures are far from most of their end users. During this thesis we studied the implementation of an fully distributed and decentralized IaaS system operating a network of micros data-centers deployed in the Internet backbone, using a modified version of OpenStack that leverages non relational databases. A prototype has been experimentally validated onGrid’5000, showing interesting results, however limited by the fact that OpenStack doesn’t take advantage of a geographically distributed functioning. Thus, we focused on adding the support of network locality to improve performance of Cloud Computing services by favoring collaborations between close nodes. A prototype of the DVMS algorithm, working with an unstructured topology based on the Vivaldi algorithm, has been validated on Grid’5000. This prototype got the first prize at the large scale challenge of the Grid’5000 spring school in 2014. Finally, the work made with DVMS enabled us to participate at the development of the VMPlaceS simulator.

The work deals with the relationship of the relational model and XML schema document and its technological and pragmatic aspects. It defines the theoretical field of data modeling at conceptual level and the two mentioned possible implementation models at the physical level. The aim is to answer the question when in the design and development of application or system it is appropriate to proceed with one of these models. Furthermore, this work also provides a general procedure for mapping conceptual schema into XML schema structures and solutions to problems that can come across during the mapping process. The problem is solved by analyzing two real issues - timetables of public transportation and the information system of a swimming school, formalized through a mechanism of predicate logic. Unlike most works on a similar topic this one varies in a pragmatic view on the problem - the concept of data, their origin, their target user and structuring.

The purpose of this project is to design, build, and implement an information retrieval database system for the Accounting Department at CSUSB. The database will focus on the financial details of the student accounts maintained by the accounting personnel. It offers detailed information pertinent to tuition, parking, housing, boarding, etc.

The mitigation of insider threats against databases is a challenging problem since insiders often have legitimate privileges to access sensitive data. Conventional security mechanisms, such as authentication and access control, are thus insufficient for the protection of databases against insider threats; such mechanisms need to be complemented with real-time anomaly detection techniques. Since the malicious activities aiming at stealing data may consist of multiple steps executed across temporal intervals, database anomaly detection is required to track users' actions across time in order to detect correlated actions that collectively indicate the occurrence of anomalies. The existing real-time anomaly detection techniques for databases can detect anomalies in the patterns of referencing the database entities, i.e., tables and columns, but are unable to detect the increase in the sizes of data retrieved by queries; neither can they detect changes in the users' data access frequencies. According to recent security reports, such changes are indicators of potential data misuse and may be the result of malicious intents for stealing or corrupting the data. In this thesis, we present techniques for monitoring database accesses and detecting anomalies that are considered early signs of data misuse by insiders. Our techniques are able to track the data retrieved by queries and sequences of queries, the frequencies of execution of periodic queries and the frequencies of referencing the database tuples and tables. We provide detailed algorithms and data structures that support the implementation of our techniques and the results of the evaluation of their implementation.<br>

<p>Doktorska disertacija pripada oblasti<br />informacionih sistema, odnosno podoblasti koja<br />se bavi upravljanjem skladi&scaron;tenjem i<br />pretraživanjem informacija. Osnovni cilj<br />disertacije je modeliranje i implementacija<br />skupa alata koji omogućavaju upotrebu fazi<br />logike u radu sa relacionim bazama podataka.<br />Da bi se do tog skupa alata do&scaron;lo, najpre je<br />relacioni model podataka pro&scaron;iren elementima<br />teorije fazi skupova, a zatim je definisano fazi<br />pro&scaron;irenje upitnog jezika SQL &ndash; PFSQL.<br />Interpreter za taj jezik je implementiran u<br />okviru fazi JDBC drajvera koji, osim<br />implementacije interpretera, sadrži i elemente<br />koji omogućavaju jednostavnu upotrebu ovih<br />mehanizama iz programskog jezika Java. Skup<br />alata je zaokružen implementacijom CASE<br />alata za razvoj fazi-relacionog modela baze<br />podataka. Osim toga, razmatrane su i<br />mogućnosti za upotrebu PFSQL jezika u<br />vi&scaron;eslojnim aplikacijama.</p> / <p>This doctoral dissertation belongs to the<br />field of information systems, subfield<br />information storage and retrieval management.<br />The main subject of the dissertation is modeling<br />and implementation of a set of tools that allow<br />usage of fuzzy logic in relational database<br />applications<br />In order to achieve that goal, at first, the<br />relational data model is extended with elements<br />of fuzzy set theory. After that, a fuzzy<br />extension of the SQL query language, called<br />PFSQL, is defined. An interpreter for that<br />language is implemented as a part of the fuzzy<br />JDBC driver. Beside the implementation of the<br />interpreter, this fuzzy JDBC driver contains<br />elements that allow simple usage of offered<br />mechanisms from Java programming language.<br />The set of tools is concluded with the<br />implementation of the CASE tool for the<br />development of fuzzy-relational data models. In<br />addition, possibilities to use PFSQL language<br />on the middle tier of multi tier systems are<br />discussed.</p>