Remarks on Category-Based Routing in Social Networks

It is well known that individuals can route messages on short paths through social networks, given only simple information about the target and using only local knowledge about the topology. Sociologists conjecture that people find routes greedily by passing the message to an acquaintance that has more in common with the target than themselves, e.g. if a dentist in Saarbr\"ucken wants to send a message to a specific lawyer in Munich, he may forward it to someone who is a lawyer and/or lives in Munich. Modelling this setting, Eppstein et al. introduced the notion of category-based routing. The goal is to assign a set of categories to each node of a graph such that greedy routing is possible. By proving bounds on the number of categories a node has to be in we can argue about the plausibility of the underlying sociological model. In this paper we substantially improve the upper bounds introduced by Eppstein et al. and prove new lower bounds.Comment: 21 page

Critical market shares for investors and access seekers and competitive models in fibre networks

In this paper we consider and evaluate NGA architectures which meet the foreseeable future bandwidth demand and allow for highest bandwidth and quality for end-users and which no longer rely on copper cable elements. These are FTTH architectures only. From all available FTTH architectures we concentrate on the two most relevant architectures in Europe, Ethernet Point-to-Point and GPON. We assume the incumbent to be the investor in the NGA network infrastructure. If the NGA architecture is based on a Point-to-Point fibre plant we have modelled the competitors as using unbundled fibre loops as the wholesale access service. If the architecture is based on a Point-to-Multipoint fibre plant, we consider an active wholesale access (bitstream access) at the MPoP or at the core network node locations. Our basic modelling relies upon an engineering bottom-up cost modelling approach. We model the total cost of the services considered under efficient conditions, taking into account the cost of all network elements needed to produce these services in the specific architecture deployed. This approach is coherent with a Long Run Incremental Cost approach as applied in regulatory economics. Our modelling approach generates a broad set of results including the relative performance of the various network architectures, investment requirements and the degree of profitable coverage. In this paper, however, we focus on the results on the potential for competition and potential market structures in an NGA environment. --NGA architecture,cost modelling,FTTH,coverage,access models,unbundling

Lebenskompetenz entwickeln im Dialog - zur Aktualität der Pädagogik Friedrich Fröbels

"Fragt man im Jahr des 175. Jubiläums der Gründung des Kindergartens nach der spezifischen Aktualität des Erbes von Werk und Person Friedrich Fröbels, zeigt sich bei Fröbel, auch im Vergleich mit den anderen „Klassikern“ der (Früh-)Pädagogik, nicht nur eine unmittelbare Anschluss-, sondern sogar eine besondere Zukunftsfähigkeit im Hinblick auf die gegenwärtigen Forschungs- und Diskussionsstränge der Frühpädagogik. Fröbels Kindheitspädagogik ist in ihrem Kern kommunikativ-dialogisch konzipiert. Sie hält insofern nach wie vor grundlegende Anregungen bereit zu den Themen phänomenographische Erfassung der Bildungsprozesse und deren curriculare Gestaltung; Kooperation zwischen Eltern und Erzieherinnen; Professionalisierung des Personals, schließlich hinsichtlich der kinderrechtlichen und bildungspolitischen sowie ökonomischen Herausforderungen und Konsequenzen. In kontrastivem Abgleich mit dem derzeit in den Bildungswissenschaften dominierenden Begründungsdiskurs der Bildungsstandards- Paradigmatik wird auf das kritische Potential der Fröbelschen Bildungstheorie verwiesen und für das Feld der Didaktik der Frühpädagogik am Beispiel der Spielpädagogik Fröbels expliziert. Für Fröbel steht dabei, wie in jüngster Zeit insbesondere in der Sozialpädagogik thematisiert, der Erwerb von Lebenskompetenz im Zentrum. Dabei besteht allerdings bei Fröbel kein Zweifel, dass eine didaktisch arrangierte Auseinandersetzung mit Welt und Selbst als Begreifen und Gestalten des eigenen Lebens nur als Prozess einer religiösen Selbstverständigung modelliert werden kann. Mit seinem Konzept vom Kindergarten als einem die 'sphärische' Grundverfasstheit der Welt repräsentierenden Ort hat er offenbar ein kontinuierlich weiterwirkendes Modell des Lebensortes für Kinder in ihrer sie jeweils umgebenden Gesellschaft nicht nur begründet, sondern auch schon experimentell erfolgreich realisiert." (Autorenreferat)"Wondering about the specific actuality of the heritage of the work and the person of Friedrich Froebel in the year of the 175th anniversary of the foundation of the kindergarten, it can be seen that Froebel's work, in comparison to other 'classics' of (early childhood) education, is not only compatible to today's research and discussions in the field of early childhood education, but is furthermore relevant for the future. The concept of Froebel's early childhood education is basically communicative-dialogic. Furthermore, it still provides essential stimuli on topics such as the phenomenographic research on educational processes and their curricular design; the cooperation of parents and educational staff, the professionalization of the staff and the challenges concerning children's rights, educational policy and economic consequences. In contrast to the currently dominating foundational discourse of educational standards, the critical potential of Froebel’s educational theory is highlighted. His theory is explicated for the field of the didactics of early childhood education using the example of Froebel's pedagogy of play. Froebel focuses on the acquisition of lifes kills similar to the current discourse in the field of social education. However, there is no doubt that the didactically arranged examination of the world and the self as an understanding and a design of the own life - according to Froebel - can only be seen as a process of a religious self-understanding. With his concept of the kindergarten as a place representing the 'spherical' basic structure of the world, Froebel did not only found but also successfully realized an ongoing setting for children in society." (author's abstract