Hierarchical contextual reasoning

Computer supported development of proofs requires user interaction even for theorems that are simple by human standards. In this thesis we define a communication infrastructure as a mediator between the user and the automatic reasoning procedures. It is based on a new uniform meta proof theory for contextual reasoning and encompasses most aspects of communication from the presentation of the proof state, via the supply of relevant contextual information about possible proof continuations, to the support for a hierarchical proof development. The proof theory is uniform for a variety of logics. It exploits proof theoretic annotations in formulas for a contextual reasoning style that is as far as possible intuitive for the user while at the same time still adequate for automatic reasoning procedures. Furthermore, concepts are defined to accomodate both the use and the explicit representation of hierarchies that are inherent in problem solving in general.Das computergestuetzte Beweisen von Theoremen erfordert den Eingriff des menschlichen Benutzers selbst fuer nach menschlichen Maßstaeben einfache Theoreme. Diese Arbeit definiert eine Kommunikationsplattform, die eine synergetische Kooperationsform des Benutzers mit dem Beweisverfahren ermöglicht

New editing techniques for video post-processing

This thesis contributes to capturing 3D cloth shape, editing cloth texture and altering object shape and motion in multi-camera and monocular video recordings. We propose a technique to capture cloth shape from a 3D scene flow by determining optical flow in several camera views. Together with a silhouette matching constraint we can track and reconstruct cloth surfaces in long video sequences. In the area of garment motion capture, we present a system to reconstruct time-coherent triangle meshes from multi-view video recordings. Texture mapping of the acquired triangle meshes is used to replace the recorded texture with new cloth patterns. We extend this work to the more challenging single camera view case. Extracting texture deformation and shading effects simultaneously enables us to achieve texture replacement effects for garments in monocular video recordings. Finally, we propose a system for the keyframe editing of video objects. A color-based segmentation algorithm together with automatic video inpainting for filling in missing background texture allows us to edit the shape and motion of 2D video objects. We present examples for altering object trajectories, applying non-rigid deformation and simulating camera motion.In dieser Dissertation stellen wir Beiträge zur 3D-Rekonstruktion von Stoffoberfächen, zum Editieren von Stofftexturen und zum Editieren von Form und Bewegung von Videoobjekten in Multikamera- und Einkamera-Aufnahmen vor. Wir beschreiben eine Methode für die 3D-Rekonstruktion von Stoffoberflächen, die auf der Bestimmung des optischen Fluß in mehreren Kameraansichten basiert. In Kombination mit einem Abgleich der Objektsilhouetten im Video und in der Rekonstruktion erhalten wir Rekonstruktionsergebnisse für längere Videosequenzen. Für die Rekonstruktion von Kleidungsstücken beschreiben wir ein System, das zeitlich kohärente Dreiecksnetze aus Multikamera-Aufnahmen rekonstruiert. Mittels Texturemapping der erhaltenen Dreiecksnetze wird die Stofftextur in der Aufnahme mit neuen Texturen ersetzt. Wir setzen diese Arbeit fort, indem wir den anspruchsvolleren Fall mit nur einer einzelnen Videokamera betrachten. Um realistische Resultate beim Ersetzen der Textur zu erzielen, werden sowohl Texturdeformationen durch zugrundeliegende Deformation der Oberfläche als auch Beleuchtungseffekte berücksichtigt. Im letzten Teil der Dissertation stellen wir ein System zum Editieren von Videoobjekten mittels Keyframes vor. Dies wird durch eine Kombination eines farbbasierten Segmentierungsalgorithmus mit automatischem Auffüllen des Hintergrunds erreicht, wodurch Form und Bewegung von 2D-Videoobjekten editiert werden können. Wir zeigen Beispiele für editierte Objekttrajektorien, beliebige Deformationen und simulierte Kamerabewegung

Online problems and two-player games : algorithms and analysis

In this thesis we study three problems that are adversarial in nature. Such problems can be viewed as a game between an algorithm and an adversary, where the adversary always tries to force the algorithm into worst-case scenarios during its execution. Many real world problems with inherent uncertainty or lack of information fit into this model. For instance, it includes the vast field of online problems where the input is only partially available and an adversary reveals the complete input gradually over time (online fashion). The algorithm has to perform efficiently under this uncertainty. In contrast to the online setting, in an offline setting, the complete input is available in the beginning. The first problem that we investigate is a classical online scheduling problem where a sequence of jobs that arrive online have to be assigned to a set of identical machines with the objective of minimizing the maximum load. We study a natural generalization of this problem where we allow migration of already scheduled jobs to other machines upon the arrival of a new job, thus bridging the gap between online and offline setting. Already for a small amount of migration, our result compares with the best results to date in both online and offline settings. From the point of view of sensitivity analysis, our results imply that, only small changes are to be made to the current schedule to accommodate a new job, if we are satisfied with near optimal solution. The other online problem that we study is the well-known metrical task systems problem. We present a probabilistic analysis of the well-known text book algorithm called the work function algorithm. Besides average-case analysis we also present smoothed analysis, which is a notion introduced recently as a hybrid between worst-case and average-case analysis. Our analysis reveals that the performance of this algorithm is much better than worst-case for a large class of inputs. This motivates us to support smoothed analysis as an alternative model for evaluating the performance of online algorithms. The third problem that we investigate is a pursuit-evasion game: an algorithm (the pursuer) has to find/catch an adversary that is \u27hiding\u27; in a graph where both players can travel in the graph. This problem belongs to the rich field of search games and it addresses the question of how long it takes for the pursuer to find the evader in a given graph that, for example, corresponds to a computer network or a geographic terrain. Such game models are also used to design efficient communication protocols. We present improved results against adversaries with varying power and also present tight lower bounds.In der vorliegenden Arbeit beschäftigen wir uns mit drei Problemen, welche als eine Art Spiel zwischen einem Algorithmus und seinem Gegenspieler interpretiert werden können. In diesem Spiel versucht der Gegenspieler, den Algorithmus während seiner Ausführung in sein Worst-Case Verhalten zu zwingen. Eine Vielzahl von praxisrelevanten Problemen, in denen nicht von Beginn an die volle Information über die Eingabeinstanz zur Verfügung steht, lassen sich als derartige Spiele modellieren. Zu dieser Klasse von Problemen gehören z. B. auch online Probleme, in denen der Gegenspieler die Eingabeinstanz für den Algorithmus online, d. h. während der Ausführung des Algorithmus, spezifiziert. Das Ziel des Algorithmus ist es, auf dieser so spezifizierten Instanz möglichst effizient zu sein. Im Gegensatz zum online Szenario kennt der Algorithmus im offline Szenario die gesamte Eingabeinstanz gleich von Beginn an. Im online Szenario wird die Effizienz eines (online) Algorithmus anhand seines Competitive Ratio gemessen. Ein Algorithmus ist c-competitive, wenn die Kosten, die der Algorithmus auf einer beliebigen online Eingabe verursacht, maximal einen Faktor c von den Kosten eines optimalen (offline) Algorithmus, der die gesamte Eingabe kennt, entfernt ist. Das erste Problem, dass wir betrachten, ist ein klassisches Scheduling Problem, in dem Jobs online eintreffen und auf identischen parallelen Maschinen verteilt werden müssen. Das Ziel ist es, die maximale Maschinenlast zu minimieren. Das zweite online Problem, dass wir betrachten, ist das Metrical Task System Problem. Als drittes Problem analysieren wir ein "Katz-und-Maus-Spiel\u27;: eine Katze (der Algorithmus) und eine Maus (der Gegenspieler) befinden sich in einem Graphen und die Katze versucht, die Maus zu fangen

Dynamic remeshing and applications

Triangle meshes are a flexible and generally accepted boundary representation for complex geometric shapes. In addition to their geometric qualities such as for instance smoothness, feature sensitivity ,or topological simplicity, intrinsic qualities such as the shape of the triangles, their distribution on the surface and the connectivity is essential for many algorithms working on them. In this thesis we present a flexible and efficient remeshing framework that improves these "intrinsic\u27; properties while keeping the mesh geometrically close to the original surface. We use a particle system approach and combine it with an iterative remeshing process in order to trim the mesh towards the requirements imposed by different applications. The particle system approach distributes the vertices on the mesh with respect to a user-defined scalar-field, whereas the iterative remeshing is done by means of "Dynamic Meshes\u27;, a combination of local topological operators that lead to a good natured connectivity. A dynamic skeleton ensures that our approach is able to preserve surface features, which are particularly important for the visual quality of the mesh. None of the algorithms requires a global parameterization or patch layouting in a preprocessing step, but works with simple local parameterizations instead. In the second part of this work we will show how to apply this remeshing framework in several applications scenarios. In particular we will elaborate on interactive remeshing, dynamic, interactive multiresolution modeling, semiregular remeshing and mesh simplification and we will show how the users can adapt the involved algorithms in a way that the resulting mesh meets their personal requirements

Realistic Rendering and Reconstruction of Astronomical Objects and an Augmented Reality Application for Astronomy

These days, there is an ever increasing need for realistic models, renderings and visualization of astronomical objects to be used in planetarium and as a tool in modern astrophysical research. One of the major goals of this dissertation is to develop novel algorithms for recovering and rendering 3D models of a specific set of astronomical objects. We first present a method to render the color and shape of the solar disc in different climate conditions as well as for different height to temperature atmospheric profiles. We then present a method to render and reconstruct the 3D distribution of reflection nebulae. The rendering model takes into account scattering and absorption to generate physically realistic visualization of reflection nebulae. Further, we propose a reconstruction method for another type of astronomical objects, planetary nebulae. We also present a novel augmented reality application called the augmented astronomical telescope, tailored for educational astronomy. The real-time application augments the view through a telescope by projecting additional information such as images, text and video related to th

Dekan der technischen Fakultät:

New approaches to protein dockin

zur Erlangung des Grades Doktor der

Subject of this thesis is the formal verification of pipelined microprocessors. This includes processors with state of the art schedulers, such as the Tomasulo scheduler and speculation. In contrast to most of the literature, we verify synthesizable design at gate level. Furthermore, we prove both data consistency and liveness. We verify the proofs using the theorem proving system PVS. We verify both in-order and out-of-order machines. For verifying in-order machines, we extend the stall engine concept presented in [MP00]. We describe and implement an algorithm that does the transformation into a pipelined machine. We describe a generic machine that supports speculating on arbitraty values. We formally verify proofs for the Tomasulo scheduling algorithm with reorder buffer