Veranstaltungsbericht - 4. Berliner Konzessionsrechtstrage 2019

Am 22. und 23. März 2019 fanden die nunmehr vierten Berliner Konzessionsrechtstage an der Freien Universität Berlin statt. Gegenstand der Tagung waren die Spannungslagen, in denen sich das Konzessionsvergaberecht nach wie vor bewegt: So hat die Diskussion um die Verortung des Konzessionsvergaberechts zwischen öffentlichem und privatem Recht und der damit konnotierten Frage nach dem richtigen Rechtsweg bis heute kein Ende gefunden. Weiterhin wird die Frage nach der Reichweite des Konzessionsbegriffs immer noch unterschiedlich beantwortet. Schließlich bedarf die Vielzahl an relevanten Rechtsregimen bei der Durchführung von Konzessionsvergabeverfahren besonderer Beachtung

Confluence reduction for Markov automata

Markov automata are a novel formalism for specifying systems exhibiting nondeterminism, probabilistic choices and Markovian rates. Recently, the process algebra MAPA was introduced to efficiently model such systems. As always, the state space explosion threatens the analysability of the models generated by such specifications. We therefore introduce confluence reduction for Markov automata, a powerful reduction technique to keep these models small. We define the notion of confluence directly on Markov automata, and discuss how to syntactically detect confluence on the MAPA language as well. That way, Markov automata generated by MAPA specifications can be reduced on-the-fly while preserving divergence-sensitive branching bisimulation. Three case studies demonstrate the significance of our approach, with reductions in analysis time up to an order of magnitude

Modelling and analysis of Markov reward automata

Costs and rewards are important ingredients for many types of systems, modelling critical aspects like energy consumption, task completion, repair costs, and memory usage. This paper introduces Markov reward automata, an extension of Markov automata that allows the modelling of systems incorporating rewards (or costs) in addition to nondeterminism, discrete probabilistic choice and continuous stochastic timing. Rewards come in two flavours: action rewards, acquired instantaneously when taking a transition; and state rewards, acquired while residing in a state. We present algorithms to optimise three reward functions: the expected cumulative reward until a goal is reached, the expected cumulative reward until a certain time bound, and the long-run average reward. We have implemented these algorithms in the SCOOP/IMCA tool chain and show their feasibility via several case studies

Researching Teenagers’ (Mobile) Interaction Orders – Methodical and Methodological Reflections on a Challenging Field

Mobile phones play an essential role in the everyday lives and social relationships of young people. They are deeply embedded in peer interactions, not only as tools but also as references of interaction. The article is based on an empirical study, which investigates how young people interpret various situations of interaction through, and related to, mobile phones. Providing a useful heuristic to reconstruct the inherent rules, claims and expectations of such situations, Goffman’s concept of the interaction order was modified in regard to youth-specific and mobile media-specific dimensions with the help of a grounded theory approach.The article deals with the methodical strategies that were applied as well as respective methodological questions that arose during the research process. In order to gain insights into the participants’ episodic and semantic knowledge about mobile media related situations, group interviews/discussions, mobile phone diaries and individual interviews were conducted. Each collection strategy is discussed in respect to its preconditions and execution. Additionally, problems regarding the role of the researcher in relation to the participants will be explicated

Bisimulation of Labeled State-to-Function Transition Systems of Stochastic Process Languages

Labeled state-to-function transition systems, FuTS for short, admit multiple transition schemes from states to functions of finite support over general semirings. As such they constitute a convenient modeling instrument to deal with stochastic process languages. In this paper, the notion of bisimulation induced by a FuTS is proposed and a correspondence result is proven stating that FuTS-bisimulation coincides with the behavioral equivalence of the associated functor. As generic examples, the concrete existing equivalences for the core of the process algebras ACP, PEPA and IMC are related to the bisimulation of specific FuTS, providing via the correspondence result coalgebraic justification of the equivalences of these calculi.Comment: In Proceedings ACCAT 2012, arXiv:1208.430

Exploring the Differential Effects of Perceived Threat on Attitudes toward Ethnic Minority Groups in Germany

Adopting a differentiated threat approach, we investigated the relationship between cultural, economic, and criminal threat on attitudes toward four different ethnic minorities in Germany (Muslims, foreigners, refugees, and Sinti and Roma). We hypothesized that the effect of different types of intergroup threats on ethnic prejudice varies with the perceived characteristics of minority groups. Using a representative sample of German adults, we found that cultural and economic threat primarily predicted attitudes toward Muslims and foreigners, while criminal threat played a minor role in attitude formation among the majority population. For refugees and Sinti and Roma, all three types of intergroup threats were found to be equally important for the prediction of attitudes toward these minority groups. These results are only partially in line with the culture-specific threat profiles of these minority groups in the German context. Therefore, we discuss the tenability of the differentiated threat approach to explain the genesis of ethnic prejudice in different cultural contexts