fundiert-entscheiden.de – mehr Sachlichkeit im medialen Raum

Diskussionen zu kontroversen Fragestellungen gesellschaftlicher Belange werden im medialen Raum durch eine fehlende strukturierte Informationsaufbereitung weniger sachlich geführt als sie sein könnten und sein sollten. Die Bereitstellung eines Entscheidungsfindungstools soll vorherrschender Unsachlichkeit entgegenwirken und Objektivität fördern. Im Hinblick auf die Missstände in den Medien wird in der vorliegenden Publikation mit fundiert-entscheiden ein solches Tool vorgestellt

Path Finding Strategies in Stochastic Networks

We introduce a novel generic algorithmic problem in directed acyclic graphs, motivated by our train delay research. Roughly speaking, an arc is admissible or not subject to the value of a random variable at its tail node. The core problem is to precompute data such that a walk along admissible arcs will lead to one of the target nodes with a high probability. In the motivating application scenario, this means to meet an appointment with a high chance even if train connections are broken due to train delays. We present an efficient dynamic-programming algorithm for the generic case. The algorithm allows us to maximize the probability of success or, alternatively, optimize other criteria subject to a guaranteed probability of success. Moreover, we customize this algorithm to the application scenario. For this scenario, we present computational results based on real data from the national German railway company. The results demonstrate that our approach is superior to the natural approach, that is, to find a fast and convenient connection and to identify alternative routes for all tight train changes where the probability that the change breaks due to delays is not negligible

A LINEAR-TIME ALGORITHM FOR EDGE-DISJOINT PATHS IN PLANAR GRAPHS

In this paper we discuss the problem of finding edge-disjoint paths in a planar, undirected graph such that each path connects two specified vertices on the boundary of the graph. We will focus on the "classical" case where an instance additionally fulfills the so-called evenness-condition. The fastest algorithm for this problem known from the literature requires O (nb/3(loglogn)l/3) time, where n denotes the number of vertices. In this paper now, we introduce a new approach to this problem, which results in an O(n) algorithm. The proof of correctness immediately yields an alternative proof of the Theorem of Okamura and Seymour, which states a necessary and sufficient condition for solvability

Reliability and Delay Distributions of Train Connections

Finding reliable train connections is a considerable issue in timetable information since train delays perturb the timetable daily. We present an effective probabilistic approach for estimating the reliability of connections in a large train network. Experiments on real customer queries and real timetables for all trains in Germany show that our approach can be implemented to deliver good results at the expense of only little processing time. Based on probability distributions for train events in connections, we estimate the reliability of connections. We have analyzed our computed reliability ratings by validating our predictions against real delay data from German Railways. This study shows that we are able to predict the feasibility of connections very well. In essence, our predictions are slightly optimistic for connections with a high rating and pretty accurate for connections with a medium rating. Only for the rare cases of a very low rating, we are too pessimistic. Our probabilistic approach already delivers good results, still has improvement potential, and offers a new perspective in the search for more reliable connections in order to bring passengers safely to their destinations even in case of delays

Kurzübersicht über UNIX/X11/Internetzugang am Beispiel des Bereichs Informatik der Universität Konstanz

Diese Schrift soll keine Einführung in die Materie geben, sondern einen Überblick über die Dienste und Werkzeuge, die durch die Rechnersysteme im Bereich Informatik zur Verfügung gestellt werden. Sie soll zugleich als Kurzreferenz und als "Einstiegspunkt" zur effizienten Nutzung von Handbüchern und On-Line-Hilfen dienen. Der Hauptteil besteht aus systematischer Hintergrundinformation über die dem System zugrundeliegenden Konzepte