Segmentation-free word spotting with bag-of-features hidden Markov models See

The method that is proposed in this thesis makes document images searchable with minimum manual effort. This works in the query-by-example scenario where the user selects an exemplary occurrence of the query word in a document image. Afterwards, an entire collection of document images is searched automatically. The major challenge is to detect relevant words and to sort them according to similarity to the query. However, recognizing text in historic document images can be considered as extrem...

Design of fault-tolerant virtual execution environments for cyber-physical systems See

The last decade revealed the vast economical and societal potential of Cyber-Physical Systems (CPS) which integrate computation with physical processes. In order to better exploit this potential, designers of CPS are trying to take advantage of novel technological opportunities provided by the unprecedented efficiency of today's hardware. There are, however, considerable challenges to this endeavor. First, there is a strong trend towards softwarization. Functions that were originally impl...

Extraction, localization, and fusion of collective vehicle data See

Maps representing the detailed features of the road network are becoming more and more important for self-driving vehicles and next generation driver assistance systems. The mapping of the road network, by specially equipped vehicles of the well-known map providers, leads to usually quarterly map updates, which might result in problems encountered by self-driving vehicles in the case that the road information is outdated. Furthermore, the provided maps could lack details, such as precise land...

Algorithmic aspects of type-based program synthesis See

In the area of type-based program synthesis, the decision problem of inhabitation (given a type environment Gamma and a type tau, is there a term M such that M can be assigned the type tau in Gamma?) corresponds to existence of a program (term M) that satisfies the given specification (type tau) under additional assumptions (type environment Gamma). Inhabitation in typed lambda-calculi can be seen as functional program synthesis from scratch. Complementarily, inhabitation in combinatory l...

Optimization and analysis for dependable application software on unreliable hardware platforms See

As chip technology keeps on shrinking towards higher densities and lower operating vol- tages, memory and logic components are now vulnerable to electromagnetic inference and radiation, leading to transient faults in the underlying hardware, which may jeopar- dize the correctness of software execution and cause so-called soft errors. To mitigate threats of soft errors, embedded-software developers have started to deploy Software- Implemented Hardware Fault Tolerance (SIHFT) techniques. H...

SACA Bench See

PG 613: ACC++ See

Autonomous Driving Using Neural Networks See

Bioinformatics from genetic variants to methylation See

An important research topic in bioinformatics is the analysis of DNA, the molecule that encodes the genetic information of all organisms. The basis for this is sequencing, a procedure in which the sequence of DNA bases is determined. In addition to the identification of variations in the base sequence itself, advances in sequencing methods and a steady reduction in sequencing costs open up new fields of research: the analysis of functionally relevant non-base-related changes, so-called ...

Uncertainty handling in surrogate assisted optimisation of games See

In this thesis entitled Uncertainty handling in surrogate assisted optimisation of games, we started out with the goal to investigate the uncertainty in game optimisation problems, as well as to identify or develop suitable optimisation algorithms. In order to approach this problem systematically, we first created a benchmark consisting of suitable game optimisation functions (GBEA). The suitability of these functions was determined using a taxonomy that was created based on the results of a ...

Contributions to computer-aided analysis of cuneiform tablet fragments See

This thesis presents methods for computer-aided three-dimensional analysis of digitized cuneiform tablets, an ancient type of writing documents. Since cuneiform script is predominantly conserved in the form of fractured clay tablet fragments, identifying matching fragments is a central task of manuscript reconstruction. This goal can benefit from the increasing 3D digitization of cuneiform fragments, which offers access to highly accurate cuneiform representations. The main contribution...

Learning attribute representations with deep convolutional neural networks for word spotting See

Understanding the contents of handwritten texts from document images has long been a traditional field of research in computer science. The ultimate goal is to automatically transcribe the text in the images into an electronic format. This would make the documents from which the images were generated much easier to access and would also allow for a fast extraction of information. Especially for historical documents a possibility to easily sift through large document image collections would...

Surrogate models for discrete optimization problems See

Surrogate models are crucial tools for many real-world optimization problems. An optimization algorithm can evaluate a data-driven surrogate model instead of an expensive objective function. While surrogate models are well-established in the continuous optimization domain, they are less frequently applied to more complex search spaces with discrete or combinatorial solution representations. The main goal of this thesis is to fill this gap. We develop and improve methods for data-driven su...

K-best enumeration - theory and application See

Where an optimal solution does not contain sufficient information about a given problem instance, enumerating good solutions is a common coping strategy. In combinatorial optimization, k-best enumeration, or ranking, has been studied and applied extensively. The k shortest simple path problem in directed, weighted graphs (kSSP), introduced in 1963 by Clarke, Krikorian and Rausen, is particularly well known. Efficient existing algorithms are based on Yen's algorithm for this problem; they all ...

Output-sensitive complexity of multiobjective combinatorial optimization with an application to the multiobjective shortest path problem See

In this thesis, we are concerned with multiobjective combinatorial optimization (MOCO) problems. We attempt to fill the gap between theory and practice, which comes from the lack of a deep complexity theory for MOCO problems. In a first part, we consider a complexity notion for multiobjective optimization problems which derives from output-sensitive complexity. The primary goal of such a complexity notion is to classify problems into easy and hard problems. We show that the multiobjectiv...

Partially supervised learning of models for visual scene and object recognition See

When creating a visual recognition system for a novel task, one of the main burdens is the collection and annotation of data. Often several thousand samples need to be manually reviewed and labeled so that the recognition system achieves the desired accuracy. The goal of this thesis is to provide methods that lower the annotation effort for visual scene and object recognition. These methods are applicable to traditional pattern recognition approaches as well as methods from the field of deep ...

On large-scale probabilistic and statistical data analysis See

In this manuscript we develop and apply modern algorithmic data reduction techniques to tackle scalability issues and enable statistical data analysis of massive data sets. Our algorithms follow a general scheme, where a reduction technique is applied to the large-scale data to obtain a small summary of sublinear size to which a classical algorithm is applied. The techniques for obtaining these summaries depend on the problem that we want to solve. The size of the summaries is usually paramet...

Exploring regular structures in strings See

This thesis is dedicated to string processing algorithms and to combinatorics on words. With respect to the former, we devise Lempel-Ziv (LZ) factorization and sparse suffix sorting algorithms. With respect to the latter, we search for all distinct squares, all maximal α-gapped repeats, and all maximal α-gapped palindromes. The topics of the presented approaches are related: for instance, our results for the LZ factorization have applications for finding all distinct squares, whereas our spar...

Markov decision processes with uncertain parameters See

Markov decision processes model stochastic uncertainty in systems and allow one to construct strategies which optimize the behaviour of a system with respect to some reward function. However, the parameters for this uncertainty, that is, the probabilities inside a Markov decision model, are derived from empirical or expert knowledge and are themselves subject to uncertainties such as measurement errors or limited expertise. This work considers second-order uncertainty models for Markov decisi...