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XML (Extensible Markup Language) ist ein sequentielles Format zur Speicherung und Übermittlung strukturierter Daten. Obwohl es ursprünglich für die Dokumentenverarbeitung entwickelt wurde, findet XML heute Verwendung in nahezu allen Bereichen der Datenverarbeitung, insbesondere aber im Internet. Jede XML-Dokumentenverarbeitungs-Software basiert auf einem XML-Parser. Der Parser liest ein Dokument in XML-Syntax ein und stellt es als Dokumentbaum der eigentlichen Anwendung zur Verfügung. Dokumentenverarbeitung ist dann im wesentlichen die Manipulation von Bäumen. Moderne funktionale Programmiersprachen wie SML und Haskell unterstützen Bäume als Basis-Datentypen und sind daher besonders gut für die Implementierung von Dokumentenverarbeitungs-Systemen geeignet. Um so erstaunlicher ist es, dass dieser Bereich zum größten Teil von Java-Software dominiert wird. Dies ist nicht zuletzt darauf zurückzuführen, dass noch keine vollständige Implementierung der XML-Syntax als Parser in einer funktionalen Programmiersprache vorliegt. Eine der wichtigsten Aufgaben in der Dokumentenverarbeitung ist Querying, d.h. die Lokalisierung von Teildokumenten, die eine angegebene Strukturbedingung erfüllen und in einem bestimmten Kontext stehen. Die baumartige Auffassung von Dokumenten in XML erlaubt die Realisierung des Querying mithilfe von Techniken aus der Theorie der Baumsprachen und Baumautomaten. Allerdings müssen diese Techniken an die speziellen Anforderungen von XML angepasst werden. Eine dieser Anforderungen ist, dass auch extrem große Dokumente verarbeitet werden müssen. Deshalb sollte der Querying-Algorithmus in einem einzigen Durchlauf durch das Dokument ausführbar sein, ohne den Dokumentbaum explizit im Speicher aufbauen zu müssen. Diese Arbeit besteht aus zwei Teilen. Der erste Teil beschreibt den XML- Parser fxp, der vollständig in SML programmiert wurde. Insbesondere werden die Erfahrungen mit SML diskutiert, die während der Implementierung von fxp gewonnen wurden. Es folgt eine Analyse des Laufzeit-Verhaltens von fxp und ein Vergleich mit anderen XML-Parsern, die in imperativen oder objekt- orientierten Programmiersprachen entwickelt wurden. Im zweiten Teil beschreiben wir einen Algorithmus zum Querying von XML- Dokumenten, der auf der Theorie der Waldautomaten fundiert ist. Er findet alle Treffer einer Anfrage in höchstens zwei Durchläufen durch das Dokument. Für eine wichtige Teilklasse von Anfragen kann das Querying sogar in einem einzelnen Durchlauf realisiert werden. Außerdem wird die Implementierung des Algorithmus in SML mit Hilfe von fxp dargestellt.

The vision of a future information and communication society has prompted leading politicians in the United States, the European Union and Japan to influence or even lead the economic and social transition in the context of an active technology policy. The technological development of society, however, is a product of a complex interplay of technological, economic and socio-political constraints. These constraints limit the political decision-making and implementation abilities. Moreover, facts and information are continuously changing during a paradigmatic technological, economic and social shift, which limits political decision-making abilities. This study compares political decision-making to promote computer-mediated communications in the Triad since the beginning of the 1980s, on four levels: the development of a political vision, the long-term aims and strategies, technology policy (e.g. the promotion of technological development and competition policy) and regulatory policy (e.g. universal access, protection of privacy and intellectual property). While technology policy tends to be uncontroversial, during a paradigmatic shift regulatory policy is difficult and lengthy. Nevertheless, the inclusion of interest groups, which rise during this paradigmatic shift and which are close to the technologies and their societal consequences, help to aid decision-making processes. In this context, politics in the United States has been more successful that in the European Union and especially Japan. Although this study predates the rise of eCommerce over the Internet, it addresses many of the themes underlying it. Of these themes, many remain politically unsettled, both on national, supranational and especially international levels. For example, for encryption and secure payments, which are necessary for eCommerce, no international standards do yet exist. The issue of taxation has hardly been opened for discussions. In sum, this study does not only offer a historical overview of the development of the Internet, but it also discusses issues of continuing present concern.

Spatial Queues
(2000)

In the present thesis, a theoretical framework for the analysis of spatial queues is developed. Spatial queues are a generalization of the classical concept of queues as they provide the possibility of assigning properties to the users. These properties may influence the queueing process, but may also be of interest for themselves. As a field of application, mobile communication networks are modeled by spatial queues in order to demonstrate the advantage of including user properties into the queueing model. In this application, the property of main interest is the user's position in the network. After a short introduction, the second chapter contains an examination of the class of Markov-additive jump processes, including expressions for the transition probabilities and the expectation as well as laws of large numbers. Chapter 3 contains the definition and analysis of the central concept of spatial Markovian arrival processes (shortly: SMAPs) as a special case of Markov-additive jump processes, but also as a natural generalization from the well-known concept of BMAPs. In chapters 4 and 5, SMAPs serve as arrival streams for the analyzed periodic SMAP/M/c/c and SMAP/G/infinity queues, respectively. These types of queues find application as models or planning tools for mobile communication networks. The analysis of these queues involves new methods such that even for the special cases of BMAP inputs (i.e. non-spatial queues) new results are obtained. In chapter 6, a procedure for statistical parameter estimation is proposed along with its numerical results. The thesis is concluded by an appendix which collects necessary results from the theories of Markov jump processes and stochastic point fields. For special classes of Markov jump processes, new results have been obtained, too.

The study at hand deals with madness as it is represented in English Canadian fiction. The topic seemed most interesting and fruitful for analysis due to the fact that as the ways madness has been defined, understood, described, judged and handled differ quite profoundly from society to society, from era to era, as the language, ideas and associations surrounding insanity are both strongly culture-relative and shifting, madness as a theme of myth and literature has always been a excellent vehicle to mirror the assumptions and arguments, the aspirations and nostalgia, the beliefs and values, hopes and fears of its age and society. Thus, while the overall intent of this study is to elucidate some discernible patterns of structure and style which accompany the use of madness in Canadian literature, to investigate the varying sorts of portrayal and the conventions of presentation, to interpret the use of madness as literary devices and to highlight the different statements which are made, the continuity, variation, and changes in the theme of madness provide an informing principle in terms of certain Canadian experiences and perceptions. By examining madness as it represents itself in Canadian literature and considering the respective explorations of the deranged mind within their historical context, I hope to demonstrate that literary interpretations of madness both reflect and question cultural, political, religious and psychological assumptions of their times and that certain symptoms or usages are characteristic of certain periods. Such an approach, it is hoped, might not only contribute towards an assessment of the wealth of associations which surround madness and the ambivalence with which it is viewed, but also shed some light on the Canadian imagination. As such this study can be considered not only as a history of literary madness, but a history of Canadian society and the Canadian mind.

The goal of this thesis is to transfer the logarithmic barrier approach, which led to very efficient interior-point methods for convex optimization problems in recent years, to convex semi-infinite programming problems. Based on a reformulation of the constraints into a nondifferentiable form this can be directly done for convex semi- infinite programming problems with nonempty compact sets of optimal solutions. But, by means of an involved max-term this reformulation leads to nondifferentiable barrier problems which can be solved with an extension of a bundle method of Kiwiel. This extension allows to deal with inexact objective values and subgradient information which occur due to the inexact evaluation of the maxima. Nevertheless we are able to prove similar convergence results as for the logarithmic barrier approach in the finite optimization. In the further course of the thesis the logarithmic barrier approach is coupled with the proximal point regularization technique in order to solve ill-posed convex semi-infinite programming problems too. Moreover this coupled algorithm generates sequences converging to an optimal solution of the given semi-infinite problem whereas the pure logarithmic barrier only produces sequences whose accumulation points are such optimal solutions. If there are certain additional conditions fulfilled we are further able to prove convergence rate results up to linear convergence of the iterates. Finally, besides hints for the implementation of the methods we present numerous numerical results for model examples as well as applications in finance and digital filter design.

Due to the breath-taking growth of the World Wide Web (WWW), the need for fast and efficient web applications becomes more and more urgent. In this doctoral thesis, the emphasis will be on two concrete tasks for improving Internet applications. On the one hand, a major problem of many of today's Internet applications may be described as the performance of the Client/Server-communication: servers often take a long time to respond to a client's request. There are several strategies to overcome this problem of high user-perceived latencies; one of them is to predict future user-requests. This way, time-consuming calculations on the server's side can be performed even before the corresponding request is being made. Furthermore, in certain situations, also the pre-fetching or the pre-sending of data might be appropriate. Those ideas will be discussed in detail in the second part of this work. On the other hand, a focus will be placed on the problem of proposing hyperlinks to improve the quality of rapid written texts, at first glance, an entirely different problem to predicting client requests. Ultra-modern online authoring systems that provide possibilities to check link-consistencies and administrate link management should also propose links in order to improve the usefulness of the produced HTML-documents. In the third part of this elaboration, we will describe a possibility to build a hyperlink-proposal module based on statistical information retrieval from hypertexts. These two problem categories do not seem to have much in common. It is one aim of this work to show that there are certain, similar solution strategies to look after both problems. A closer comparison and an abstraction of both methodologies will lead to interesting synergetic effects. For example, advanced strategies to foresee future user-requests by modeling time and document aging can be used to improve the quality of hyperlink-proposals too.

This work is concerned with arbitrage bounds for prices of contingent claims under transaction costs, but regardless of other conceivable market frictions. Assumptions on the underlying market are held as weak as convenient for the deduction of meaningful results that make good economic sense. In discrete time we also allow for underlying price processes with uncountable state space. In continuous time the underlying price process is modeled by a semimartingale. For the most part we could avoid any stronger assumptions. The main problems with which we deal in this work are the modelling of (proportional) transaction costs, Fundamental Theorems of Asset Pricing under transaction costs, dual characterizations of arbitrage bounds under transaction costs, Quantile-Hedging under transaction costs, alternatives to the Black-Scholes model in continuous time (under transaction costs). The results apply to stock and currency markets.

In this thesis we focus on the development and investigation of methods for the computation of confluent hypergeometric functions. We point out the relations between these functions and parabolic boundary value problems and demonstrate applications to models of heat transfer and fluid dynamics. For the computation of confluent hypergeometric functions on compact (real or complex) intervals we consider a series expansion based on the Hadamard product of power series. It turnes out that the partial sums of this expansion are easily computable and provide a better rate of convergence in comparison to the partial sums of the Taylor series. Regarding the computational accuracy the problem of cancellation errors is reduced considerably. Another important tool for the computation of confluent hypergeometric functions are recurrence formulae. Although easy to implement, such recurrence relations are numerically unstable e.g. due to rounding errors. In order to circumvent these problems a method for computing recurrence relations in backward direction is applied. Furthermore, asymptotic expansions for large arguments in modulus are considered. From the numerical point of view the determination of the number of terms used for the approximation is a crucial point. As an application we consider initial-boundary value problems with partial differential equations of parabolic type, where we use the method of eigenfunction expansion in order to determine an explicit form of the solution. In this case the arising eigenfunctions depend directly on the geometry of the considered domain. For certain domains with some special geometry the eigenfunctions are of confluent hypergeometric type. Both a conductive heat transfer model and an application in fluid dynamics is considered. Finally, the application of several heat transfer models to certain sterilization processes in food industry is discussed.

This work is concerned with the numerical solution of optimization problems that arise in the context of ground water modeling. Both ground water hydraulic and quality management problems are considered. The considered problems are discretized problems of optimal control that are governed by discretized partial differential equations. Aspects of special interest in this work are inaccurate function evaluations and the ensuing numerical treatment within an optimization algorithm. Methods for noisy functions are appropriate for the considered practical application. Also, block preconditioners are constructed and analyzed that exploit the structure of the underlying linear system. Specifically, KKT systems are considered, and the preconditioners are tested for use within Krylov subspace methods. The project was financed by the foundation Stiftung Rheinland-Pfalz für Innovation and carried out in joint work with TGU GmbH, a company of consulting engineers for ground water and water resources.