Showing papers by "University of Passau published in 2003"

How Corruption Affects Productivity

Abstract: Corruption is likely to lower the productivity of capital due to a variety of channels. Corruption renders governments incapable or unwilling to achieve public welfare as a result of x-inefficiency, wasteful rent-seeking or distorted public decisions (Bardhan 1997, Rose-Ackerman 1999, Lambsdorff 2002a). The allocation of capital goods will not be optimal when affected by corruption because those projects that promise large side-payments and exhibit low risks of detection are preferred to those that benefit the public at large. The best-connected contractors and those most willing to offer bribes are preferred to those offering the best product. The quality of investments will suffer from corruption because control mechanisms, required to guarantee the contracted quality level, can be circumvented. Public servants are appointed based on nepotism or bribe payments while aspects of efficiency and capacity are disregarded. The effort level of public servants suffers from adverse incentives because creating artificial bottlenecks can increase the need for paying speed-money. The most visible sign of the adverse impact of corruption are ‘white-elephant projects’, that is, projects that totally disregard public demand or that are wrecked shortly after completion (Mauro 1997). There exists strong empirical support for the adverse impact of corruption on the ratio of investment to GDP (Mauro 1995 and 1997, Knack and Keefer 1995, Campos, Lien and Pradhan 1999, Brunetti, Kisunko and Weder 1997: pp. 23, 25 and Brunetti and Weder 1998: pp. 526, 528). Equally there is substantial evidence for an adverse impact of corruption on foreign direct investments and capital inflows (Wei 2000, Lambsdorff 2003). But there exists no

Experiments on Graph Clustering Algorithms

Abstract: A promising approach to graph clustering is based on the intuitive notion of intra-cluster density vs. inter-cluster sparsity. While both formalizations and algorithms focusing on particular aspects of this rather vague concept have been proposed no conclusive argument on their appropriateness has been given. As a first step towards understanding the consequences of particular con- ceptions, we conducted an experimental evaluation of graph clustering approaches. By combining proven techniques from graph partitioning and geometric clustering, we also introduce a new approach that compares favorably.

A comparison of event models for Naive Bayes anti-spam e-mail filtering

Abstract: We describe experiments with a Naive Bayes text classifier in the context of anti-spam E-mail filtering, using two different statistical event models: a multi-variate Bernoulli model and a multinomial model. We introduce a family of feature ranking functions for feature selection in the multinomial event model that take account of the word frequency information. We present evaluation results on two publicly available corpora of legitimate and spam E-mails. We find that the multinomial model is less biased towards one class and achieves slightly higher accuracy than the multi-variate Bernoulli model.

How corruption affects persistent capital flows

Abstract: Corruption is known to reduce the ratio of investment to GDP. This study breaks down investment into domestic savings and net capital inflows. A significant impact of corruption exists only for the latter variable because the first variable is distorted by general equilibrium repercussions. An increase in Colombia’s level of integrity to that of the United Kingdom is found to increase net annual capital inflows by 3 percent of GDP. Decomposing this impact reveals that bureaucratic quality, civil liberty and government stability are irrelevant, but that a country’s law and order tradition is a crucial sub-component for attracting capital.

Visual unrolling of network evolution and the analysis of dynamic discourse

Abstract: We introduce a method for visualizing evolving networks. In addition to the intermediate states of the network, it conveys the nature of change between states by unrolling the dynamics of the network. Each modification is shown in a separate layer of a three-dimensional representation, where the stack of layers corresponds to a time line of the evolution. We focus on networks of dynamic discourse as the driving application, but the method extends to any type of networks evolving in similar ways.

Antecedents and consequences of corporate governance reform: the case of Germany

Abstract: The paper examines the antecedents and consequences of the voluntary adoption of corporate governance reform in firms embedded in a relationship-based governance system with less protection of minority shareholders. In such locations, ownership structure should be a key determinant of governance reform. Firms with dispersed ownership are likely to face agency problems but may lack sufficient ownership power in the hand of external owners for adoption to occur. Extensive ownership by external parties facilitates adoption but decreases the need and motivation to adopt governance reform. We examined the adoption of stock-based incentive plans and transparent accounting regulations (e.g., greater disclosure to shareholders) among large German firms (DAX 100) during the late 1990s. We found an inverse ‘U’-shaped relationship between ownership concentration and governance reform. In addition, we found that firms adopting governance reform were more likely to engage in corporate divestitures and achieve higher levels of market performance than firms not adopting governance reform. Copyright © 2003 John Wiley & Sons, Ltd.

Communicating centrality in policy network drawings

Abstract: We introduce a network visualization technique that supports an analytical method applied in the social sciences. Policy network analysis is an approach to study policy making structures, processes, and outcomes, thereby concentrating on relations between policy actors. An important operational concept for the analysis of policy networks is the notion of centrality, i.e., the distinction of actors according to their importance in a relational structure. We integrate this measure in a layout model for networks by mapping structural to geometric centrality. Thus, centrality values and network data can be presented simultaneously and explored interactively.

Context-sensitive slicing of concurrent programs

Abstract: Program slicing is a technique to identify statements that may influence the computations at other statements. Precise slicing has been shown to be undecidable for concurrent programs. This work presents the first context-sensitive approach to slice concurrent programs accurately. It extends the well known structures of the control flow graph and the (interprocedural) program dependence graph for concurrent programs with interference. This new technique does not require serialization or inlining.

Computer algebra systems

Abstract: Short descriptions of computer algebra systems are presented in three sections: major systems, special purpose systems, and packages. However, the separation between special purpose systems and packages is not to be taken too literally. An older survey is the paper by Calmet and van Hulzen in [Buchberger et al. 1982]. There is now an excellent new book by Wester [Wester 1999] that covers computer algebra systems.

Market structure and the taxation of international trade

Abstract: The paper compares non-cooperative commodity taxation under the destina- tion and origin principles under a variety of different assumptions about market structure. We consider a model of international duopoly with either quantity or price competition of firms and either segmented or integrated markets, and a mo- nopolistic competition model with mobile firms. In each setting the international spillovers of tax policy are isolated and evaluated at the Pareto efficient tax rate. The sign of the net spillover, and thus the direction that commodity tax com- petition will take, depends critically on whether lump-sum taxes are available or commodity taxes must be used to finance the government budget.

Selected open problems in graph drawing

Abstract: In this manuscript, we present several challenging and interesting open problems in graph drawing. The goal of the listing in this paper is to stimulate future research in graph drawing.

Reliable Web Service Execution and Deployment in Dynamic Environments

Abstract: In this work, we present novel techniques for flexible and reliable execution and deployment of Web services which can be integrated into existing service platforms The first technique, dynamic service selection, provides a layer of abstraction for service invocation offering Web services the possibility of selecting and invoking Web services at runtime based on a technical specification of the desired service The selection can be influenced by using different types of constraints The second technique, a generic dispatcher service capable of automatic service replication, augments Web services with load balancing and high availability features, without having to consider these features at the services’ development We implemented these techniques within the ServiceGlobe system, an open Web service platform

Visualizing Related Metabolic Pathways in Two and a Half Dimensions

Abstract: We propose a method for visualizing a set of related metabolic pathways using 2 1 D graph drawing. Interdependent, two- dimensional layouts of each pathway are stacked on top of each other so that biologists get a full picture of subtle and significant differences among the pathways. Layouts are determined by a global layout of the union of all pathway-representing graphs using a variant of the proven Sugiyama approach for layered graph drawing that allows edges to cross if they appear in different graphs.

New firm formation by industry over space and time: A multi-level analysis

Abstract: We apply a multi-level approach to analyze simultaneously the effects of three groups of determinants on new firm formation: industry, location and change over time. The data is for West Germany and covers the 1983-97 period. Our analysis indicates that innovation activities and the technological regime play a significant role in new firm formation processes. There are some differences with regard to the impact of a number of variables on start-ups in manufacturing and the service sector. Changes in demand are conducive to new firm formation while a high level of unemployment in a region obviously creates a relatively uncomfortable environment for setting up new businesses.

Functional Quantization and Small Ball Probabilities for Gaussian Processes

Abstract: Quantization consists in studying the L r -error induced by the approximation of a random vector X by a vector (quantized version) taking a finite number n of values. We investigate this problem for Gaussian random vectors in an infinite dimensional Banach space and in particular, for Gaussian processes. A precise link proved by Fehringer(4) and Dereich et al. (3) relates lower and upper bounds for small ball probabilities with upper and lower bounds for the quantization error, respectively. We establish a complete relationship by showing that the same holds for the direction from the quantization error to small ball probabilities. This allows us to compute the exact rate of convergence to zero of the minimal L r -quantization error from logarithmic small ball asymptotics and vice versa.

Evolutionary optimization of radial basis function networks for intrusion detection

Abstract: Feature selection and architecture optimization are two key tasks in most neural network applications. Appropriate input features must be selected from a given (and often large) set of possible features and architecture parameters of the network such as the number of hidden neurons or learning parameters must be adapted with respect to the selected features and a learning data set. This article sets out an evolutionary algorithm (EA) that performs the tasks simultaneously for radial basis function (RBF) networks. The feasibility and the benefits of this approach are demonstrated in an application in the area of computer security: the detection of attacks (intrusive behavior) in computer networks. The EA, however, is independent from the application example given so that the ideas and solutions may easily be transferred to other applications and even other neural network paradigms. In the application example investigated overall classification rates of about 99.4% (average of eight attack types) can be reached for independent validation data.

Distributed Queries and Query Optimization in Schema-Based P2P-Systems

Abstract: Databases have employed a schema-based approach to store and retrieve structured data for decades. For peer-to-peer (P2P) networks, similar approaches are just beginning to emerge, also motivated by the fact, that sending (atomic) queries to the appropriate peers clearly fails for queries which need data from more than one peer to be executed. While quite a few database techniques can be re-used in this new context, a P2P data management infrastructure poses additional challenges which have to be solved before schema-based P2P networks become as common as schema-based databases. Because of the dynamic nature of P2P networks, we can neither assume global knowledge about data distribution, nor are static topologies and static query plans suitable for these networks. Unlike in traditional distributed database systems, we cannot assume a complete schema instance but rather work with a distributed schema which directs query processing tasks from one node to one or more neighboring nodes.

Barrier slicing and chopping

Abstract: One of the critiques on program slicing is that slices presented to the user are hard to understand. This is partly due to bad user interfaces, but mainly related to the problem that slicing 'dumps' the results onto the user without any explanation. We present an approach that can be used to 'filter' slices. This approach basically introduces 'barriers' which are not allowed to be passed during slice computation. An earlier filtering approach is chopping which is also extended to obey such a barrier. The barrier variants of slicing and chopping provide filtering possibilities for smaller slices and better comprehensibility.

Quality of service in an information economy

Abstract: Accessing and processing distributed data sources have become important factors for businesses today. This is especially true for the emerging virtual enterprises with their data and processing capabilities spread across the Internet. Unfortunately, however, query processing on the Internet is not predictable and robust enough to meet the requirements of many business applications. For instance, the response time of a query can be unexpectedly high; or the monetary cost might be too high if the partners charge for the usage of their data or processing capabilities; or the result of the query might be useless because it is based on outdated data or only on parts (rather than all) of the available data. In this work, we show how a distributed query processor can be extended in order to support quality of service (QoS) guarantees. We propose ways to integrate QoS management into the various phases of query processing: (1) Query optimization uses a multi-dimensional assessment (cost, time and result quality) of query plans, (2) query plan instantiation comprises an admission control for sub-plans, and (3) during query plan execution the QoS of the query is monitored and a fuzzy controller initiates repairing actions if needed. The goal of our work is to provide an initial step towards QoS management in distributed query processing systems and do significantly better than current distributed database systems, which are based on a best-effort policy.

A generic projection operator for partial cylindrical algebraic decomposition

Abstract: This paper provides a starting point for generic quantifier elimination by partial cylindrical algebraic decomposition pcad. On input of a first-order formula over the reals generic pcad outputs a theory and a quantifier-free formula. The theory is a set of negated equations in the free variables of the input formula. The quantifier-free formula is equivalent to the input for all parameter values satisfying the theory. For obtaining this generic elimination procedure, we derive a generic projection operator from the standard Collins--Hong projection operator. Our operator particularly addresses formulas with many parameters thus filling a gap in the applicability of pcad. It restricts decomposition to a reasonable subset of the entire space. The above-mentioned theory describes this subset. The approach is compatible with other improvements in the framework of pcad. It turns out that the theory contains assumptions that are easily interpretable and that are most often non-degeneracy conditions. The applicability of our generic elimination procedure significantly extends that of the corresponding regular procedure. Our procedure is implemented in the computer logic system redlog.

Rule extraction from neural networks for intrusion detection in computer networks

Abstract: In many neural network applications, the understanding of the network functionality is an important issue. Trained neural networks are often termed as "black boxes" which do not allow to get a deeper insight into the relationships between the input (feature) and output spaces. In the past years some researchers addressed the problem of rule extraction from trained neural networks. This article investigates the properties and results of different rule extraction techniques in a specific application area: The detection of intrusions in computer networks. This application area is chosen because intrusion detection and the development of appropriate intrusion detection systems (IDS) gains more and more importance with the rapidly increasing impact of the Internet.

Unions of slices are not slices

Abstract: Many approaches to slicing rely upon the 'fact' that the union of two static slices is a valid slice. It is known that static slices constructed using program dependence graph algorithms are valid slices (Reps and Yang, 1988). However, this is not true for other forms of slicing. For example, it has been established that the union of two dynamic slices is not necessarily a valid dynamic slice (Hall, 1995). In this paper this result is extended to show that the union of two static slices is not necessarily a valid slice, based on Weiser's definition of a (static) slice. We also analyse the properties that make the union of different forms of slices a valid slice.

Fragmentation, Efficiency‐Seeking FDI, and Employment

Abstract: The paper examines the impact of efficiency-seeking FDI on factor prices, employment, and output. The analysis shows that when transportation costs fall, companies start relocating labor-intensive production processes to low-wage countries. But this does not necessarily hurt workers in the high-wage country. The paper demonstrates an employment-depressing \"relocation effect\" and an employment-enhancing \"efficiency effect.\" Employment is more likely to rise if the internationality of production is high and if the supply of capital is elastic. Furthermore, the model is capable of explaining intraindustry cross-hauling.

Attribute Grammars for Scalable Query Processing on XML Streams

Abstract: We introduce the new notion of XML Stream Attribute Grammars (XSAGs). XSAGs are the first scalable query language for XML streams (running strictly in linear time with bounded memory consumption independent of the size of the stream) that allows for actual data transformations rather than just document filtering. XSAGs are also relatively easy to use for humans. Moreover, the XSAG formalism provides a strong intuition for which queries can or cannot be processed scalably on streams. We introduce XSAGs together with the necessary language-theoretic machinery, study their theoretical properties such as their expressiveness and complexity, and discuss their implementation.

Intrusion detection in computer networks with neural and fuzzy classifiers

Abstract: With the rapidly increasing impact of the Internet, the development of appropriate intrusion detection systems (IDS) gains more and more importance. This article presents a performance comparison of four neural and fuzzy paradigms (multilayer perceptrons, radial basis function networks, NEFCLASS systems, and classifying fuzzy-k-means) applied to misuse detection on the basis of TCP and IP header information. As an example, four different attacks (Nmap, Portsweep, Dict, Back) will be detected utilising evaluation data provided by the Defense Advanced Research Projects Agency (DARPA). The best overall classification results (99.42%) can be achieved with radial basis function networks, which model hyperspherical clusters in the feature space.

Debate on the enlargement of the European Union The enlargement crisis of the European Union: limits of the dialectics of integration and expansion

Abstract: The enlargement crisis of the EU has been triggered by problems related to enlargement towards the east but its roots extend far beyond that issue. To date, European integration has developed within a structure of a wealthy core territory and concentric circles around this centre. The emergence of this pattern has been driven by the dialectics of integration and expansion. But the institutional obstacles and legitimation problems linked to EU eastward enlargement indicate that very little room for manoeuvre remains for future expansion of the EU. As the expansion process reaches its limits, differentiated forms of EU integration, creating different classes of EU members, are likely to appear.