004 Datenverarbeitung; Informatik
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Multi-agent systems are a mature approach to model complex software systems by means of Agent-Oriented Software Engineering (AOSE). However, their application is not widely accepted in mainstream software engineering. Parallel to this the interdisciplinary field of Agent-based Social Simulation (ABSS) finds increasing recognition beyond the purely academic realm which starts to draw attention from the mainstream of agent researchers. This work analyzes factors to improve the uptake of AOSE as well as characteristics which separate the two fields AOSE and ABSS to understand their gap. Based on the efficiency-oriented micro-agent concept of the Otago Agent Platform (OPAL) we have constructed a new modern and self-contained micro-agent platform called µ². The design takes technological trends into account and integrates representative technologies, such as the functionally-inspired JVM language Clojure (with its Transactional Memory), asynchronous message passing frameworks and the mobile application platform Android. The mobile version of the platform shows an innovative approach to allow direct interaction between Android application components and micro-agents by mapping their related internal communication mechanisms. This empowers micro-agents to exploit virtually any capability of mobile devices for intelligent agent-based applications, robotics or simply act as a distributed middleware. Additionally, relevant platform components for the support of social simulations are identified and partially implemented. To show the usability of the platform for simulation purposes an interaction-centric scenario representing group shaping processes in a multi-cultural context is provided. The scenario is based on Hofstede's concept of 'Cultural Dimensions'. It does not only confirm the applicability of the platform for simulations but also reveals interesting patterns for culturally augmented in- and out-group agents. This explorative research advocates the potential of micro-agents as a powerful general system modelling mechanism while bridging the convergence between mobile and desktop systems. The results stimulate future work on the micro-agent concept itself, the suggested platform and the deeper exploration of mechanisms for seemless interaction of micro-agents with mobile environments. Last but not least the further elaboration of the simulation model as well as its use to augment intelligent agents with cultural aspects offer promising perspectives for future research.
Knowledge compilation is a common technique for propositional logic knowledge bases. A given knowledge base is transformed into a normal form, for which queries can be answered efficiently. This precompilation step is expensive, but it only has to be performed once. We apply this technique to concepts defined in the Description Logic ALC. We introduce a normal form called linkless normal form for ALC concepts and discuss an efficient satisability test for concepts given in this normal form. Furthermore, we will show how to efficiently calculate uniform interpolants of precompiled concepts w.r.t. a given signature.
This thesis introduces fnnlib, a C++ library for recurrent neural network simulations that I developed between October 2009 and March 2010 at Osaka University's Graduate School of Engineering. After covering the theory behind recurrent neural networks, backpropagation through time, recurrent neural networks with parametric bias, continuous-time recurrent neural networks, and echo state networks, the design of the library is explained. All of the classes as well as their interrelationships are presented along with reasons as to why certain design decisions were made. Towards the end of the thesis, a small practical example is shown. Also, fnnlib is compared to other neural network libraries.
This thesis presents an analysis of API usage in a large corpus of Java software retrieved from the open source repositories hosted at SourceForge. Most larger software projects use software libraries, which offer a public "application programming interface" or API as an interface for the programmer. In order to facilitate the transition between different APIs, there are emerging research projects in the field of automated API migration. However, there is a lack of basic statistical background information about in-the-wild usage of APIs as such measurements have, until now, only been done on rather small corpora. We thus present an analysis method suitable for measurements with large corpora. First, we create a corpus of open source projects hosted on SourceForge, as well as a corpus of software libraries. Then, all projects in the corpus are compiled with an instrumented compiler. We use a compiler plugin for javac that gives detailed information about every method created by the compiler. This information is stored in a database and analyzed.
Specifying behaviors of multi-agent systems (MASs) is a demanding task, especially when applied in safety-critical systems. In the latter systems, the specification of behaviors has to be carried out carefully in order to avoid side effects that might cause unwanted or even disastrous behaviors. Thus, formal methods based on mathematical models of the system under design are helpful. They not only allow us to formally specify the system at different levels of abstraction, but also to verify the consistency of the specified systems before implementing them. The formal specification aims a precise and unambiguous description of the behavior of MASs, whereas the verification aims at proving the satisfaction of specified requirements. A behavior of an agent can be described as discrete changes of its states with respect to external or internal actions. Whenever an action occurs, the agent moves from one state to another one. Therefore, an efficient way to model this type of discrete behaviors is to use a kind of state transition diagrams such as finite automata. One remarkable advantage of such transition diagrams is that they lend themselves formal analysis techniques using model checking. The latter is an automatic verification technique which determines whether given properties are satisfied within a model underlying a particular system. In realistic physical environments, however, it is necessary to consider continuous behaviors in addition to discrete behaviors of MASs. Examples of those type of behaviors include the movement of a soccer agent to kick off or to go to the ball, the process of putting out the fire by a fire brigade agent in a rescue scenario, or any other behaviors that depend on any timed physical law. The traditional state transition diagrams are not sufficient to combine these types of behaviors. Hybrid automata offer an elegant method to capture such types of behaviors. Hybrid automata extend regular state transition diagrams with methods that deal with those continuous actions such that the state transition diagrams are used to model the discrete changes of behaviors, while differential equations are used to model the continuous changes. The semantics of hybrid automata make them accessible to formal verification by means of model checking. The main goal of this thesis is to approach hybrid automata for specifying and verifying behaviors of MASs. However, specifying and and verifying behaviors of MASs by means of hybrid automata raises several issues that should be considered. These issues include the complexity, modularity, and the expressiveness of MASs' models. This thesis addresses these issues and provides possible solutions to tackle them.
Texture-based text detection in digital images using wavelet features and support vector machines
(2010)
In this bachelor thesis a new texture-based approach for the detection of text in digital images is presented. The procedure can be essentially divided into two main tasks, in detection of text blocks and detection of individual words, whereby the individual words are extracted from the detected text blocks. Roughly, the developed method acts with multiple support vector machines, which classify possible text regions of an image into real text regions, using wavelet-based features. In the process the possible text regions are defifined by edge projections with diσerent orientations. The results of the approach are X/Y coordinates, width and height of rectangular regions of an image, which contains individual words. This knowledge can be further processed, for example by an optical character recognition software to get the important and useful text information.
Ontologies play an important role in knowledge representation for sharing information and collaboratively developing knowledge bases. They are changed, adapted and reused in different applications and domains resulting in multiple versions of an ontology. The comparison of different versions and the analysis of changes at a higher level of abstraction may be insightful to understand the changes that were applied to an ontology. While there is existing work on detecting (syntactical) differences and changes in ontologies, there is still a need in analyzing ontology changes at a higher level of abstraction like ontology evolution or refactoring pattern. In our approach we start from a classification of model refactoring patterns found in software engineering for identifying such refactoring patterns in OWL ontologies using DL reasoning to recognize these patterns.
Mobile payment has been a payment option in the market for a long time now and was predicted to become a widely used payment method. However, over the years, the market penetration rate of mPayments has been relatively low, despite it having all characteristics required of a convenient payment method. The primaryrnreason for this has been cited as a lack of customer acceptance mainly caused due to the lack of perceived security by the end-user. Although biometric authentication is not a new technology, it is experiencing a revival in the light of the present day terror threats and increased security requirements in various industries. The application of biometric authentication in mPayments is analysed here and a suitable biometric authentication method for use with mPayments is recommended. The issue of enrolment, human and technical factors to be considered are discussed and the STOF business model is applied to a BiMoP (biometric mPayment) application.
In recent years ontologies have become common on the WWW to provide high-level descriptions of specific domains. These descriptions could be effectively used to build applications with the ability to find implicit consequences of their represented knowledge. The W3C developed the Resource Description Framework RDF, a language to describe the semantics of the data on the web, and the Ontology Web Language OWL, a family of knowledge representation languages for authoring ontologies. In this thesis we propose an ontology API engineering framework that makes use of the state-of-the-art ontology modeling technologies as well as of software engineering technologies. This system simplifies the design and implementation process of developing dedicated APIs for ontologies. Developers of semantic web applications usually face the problem of mapping entities or complex relations described in the ontology to object-oriented representations. Mapping complex relationship structures that come with complex ontologies to a useful API requires more complicated API representations than does the mere mapping of concepts to classes. The implementation of correct object persistence functions in such class representations also becomes quite complex.