How Much Lookahead is Needed to Win Infinite Games?

Delay games are two-player games of infinite duration in which one player may delay her moves to obtain a lookahead on her opponent's moves. For $\omega$-regular winning conditions it is known that such games can be solved in doubly-exponential time and that doubly-exponential lookahead is sufficient. We improve upon both results by giving an exponential time algorithm and an exponential upper bound on the necessary lookahead. This is complemented by showing EXPTIME-hardness of the solution problem and tight exponential lower bounds on the lookahead. Both lower bounds already hold for safety conditions. Furthermore, solving delay games with reachability conditions is shown to be PSPACE-complete. This is a corrected version of the paper https://arxiv.org/abs/1412.3701v4 published originally on August 26, 2016

Prompt Delay

Delay games are two-player games of infinite duration in which one player may delay her moves to obtain a lookahead on her opponent's moves. Recently, such games with quantitative winning conditions in weak MSO with the unbounding quantifier were studied, but their properties turned out to be unsatisfactory. In particular, unbounded lookahead is in general necessary. Here, we study delay games with winning conditions given by Prompt-LTL, Linear Temporal Logic equipped with a parameterized eventually operator whose scope is bounded. Our main result shows that solving Prompt-LTL delay games is complete for triply-exponential time. Furthermore, we give tight triply-exponential bounds on the necessary lookahead and on the scope of the parameterized eventually operator. Thus, we identify Prompt-LTL as the first known class of well-behaved quantitative winning conditions for delay games. Finally, we show that applying our techniques to delay games with \omega-regular winning conditions answers open questions in the cases where the winning conditions are given by non-deterministic, universal, or alternating automata

Evaluierung von sechs Fotofallenmodellen hinsichtlich der Eignung für Fang-Wiederfang Methoden beim Eurasischen Luchs (Lynx lynx)

Digital outdoor cameras are increasingly used in wildlife research because they allow species inventories, population estimates, and behavior or activity observations. Which camera model is suitable and practical depends on environmental conditions, focus species and specific scientific questions posed. Here we focused on testing cameras appropriate for elusive species that can be identified visually owing to individual coat patterns. Specifically the camera should be adequate for calculating the minimum population of Eurasian Lynx (Lynx lynx) during a systematic monitoring with camera traps. Therefore we tested six digital camera models with regard to trigger speed and the image quality necessary for visual identification of pacing lynx on trails. The decision if a camera model is adequate for the scientific goal was regulated due to priority levels under laboratory conditions. Only one camera model proved to be suitable for camera-trap monitoring. Our practical camera test can be used to evaluate newer models of digital cameras as they become available. This application opens an avenue for a non-invasive population monitoring of rare and elusive species in a low mountain range area.Digitale Fotofallen werden weltweit in der Wildtierforschung eingesetzt. Die Einsatzgebiete sind vielfältig, sie reichen von Artenbestandsaufnahmen und Populationsschätzungen über die Verhaltensforschung bis hin zu Aktivitätsanalysen. Das jeweilig eingesetzte Kameramodell muss an die Aufnahmesituation und die Zielsetzung der Analyse angepasst sein. Das Ziel unseres Fotofallentests war es, ein Modell zu finden, welches für die visuelle Identifizierung von Fellmustern des Eurasischen Luchses geeignet ist. Die Fotofalle soll in einem systematischen Monitoring für die minimale Anzahl der im Gebiet vorkommenden Luchse und deren Populationsschätzung mit Fang-Wiederfang Methoden eingesetzt werden können. Bei dem Test von sechs Fotofallenmodellen, fiel das Hauptaugenmerk auf die Auslösegeschwindigkeit und die Bildqualität welche die nötigen Faktoren für die Sicherstellung der visuellen Identifikation von schreitenden Luchsen am Wildwechsel darstellen. Zur Entscheidungsfindung der Eignung eines Fotofallenmodells für die Fragestellung definierten wir Prioritätslevel unter Laborbedingungen. Es stellte sich heraus, dass nur ein Fotofallenmodell die Ansprüche erfüllte. Der praktische Fotofallentest kann für neuerscheinende Fotofallenmodelle adaptiert werden. Diese Anwendung eröffnet die Möglichkeit für ein nicht invasives Monitoring in Mittelgebirgslandschaften

Strict irreducibility of Markov kernels and ergodicity of step skew products

We consider step skew products arising from bundles of measure preserving transformations, which act on a common probability space and are chosen at random by a stationary ergodic Markov chain. In many contexts it is desirable to know whether ergodicity of the bundle implies ergodicity of the skew product. Introducing the notion of strict irreducibility for Markov kernels we shall characterize the class of Markov chains for which the aforementioned implication holds true. We thereby extend a sufficient condition of Bufetov for the case of finite state Markov chains to general state spaces and show that it is in fact also necessary. As an application we obtain an explicit description of the limit in ergodic theorems for random dynamical systems of Markov type.Comment: main results extended from countable state spaces to arbitrary state spaces, title changed accordingly, one author added (P.L.), 20 page

Evaluation and Optimization of Heliostat Calibration Methods

In solar tower power plants, the sun's energy is focused onto a receiver at the top of a solar tower by means of many biaxially movable mirrors (heliostats) and the high energy density generated is used, for example, to generate electricity via a steam power process or to trigger chemical processes for the production of new types of fuels. It is very important that the heliostats track the movement of the sun correctly throughout the day, so that the incoming solar rays are reflected as accurately as possible onto a defined point on the tower. To achieve this, motor positions of the two linear actuators, which change the orientation of the heliostats, are calculated from an error-prone kinematic geometry model of the individual heliostats. To minimize alignment errors, selected parameters of the geometry model are adjusted by means of a regression to calibration data recorded by the camera-target method. Within the scope of this work, on the one hand, the regression method used is investigated and improvements and further algorithms are tested and developed. On the other hand, the selection of optimization parameters from the geometry model is analyzed. It was found that changing the regression methodology does not improve the alignment accuracy. However, a selection of optimization parameters and their optimization order could be found that indicate a significant reduction of the alignment error

Extracting partial decay rates of helium from complex rotation: autoionizing resonances of the one-dimensional configurations

Partial autoionization rates of doubly excited one-dimensional helium in the collinear Zee and eZe configuration are obtained by means of the complex rotation method. The approach presented here relies on a projection of back-rotated resonance wave functions onto singly ionized $\textrm{He}^{+}$ channel wave functions and the computation of the corresponding particle fluxes. In spite of the long-range nature of the Coulomb potential between the electrons and the nucleus, an asymptotic region where the fluxes are stationary is clearly observed. Low-lying doubly excited states are found to decay predomintantly into the nearest single-ionization continuum. This approach paves the way for a systematic analysis of the decay rates observed in higher-dimensional models, and of the role of electronic correlations and atomic structure in recent photoionization experiments

Ultrashort pulse induced nanostructures in transparent materials

Glass fascinates mankind since its first discovery about 30 thousand years ago. Besides the challenging conditions for fabricating glasses with homogeneous properties the technological prospects for precise machining were first developed in the last millennium. While core areas of glass processing were dominated by well-established mechanical techniques such as scribing, grinding, sawing and polishing the technological progress and ongoing miniaturization demanded alternative processing tools. Within the end of the 20th century the development of ultrashort pulse laser systems paved the way for precise and cost-efficient solutions for materials processing in key technologies such as computer chips, medical surgery or in the field of automotive. Even more, the short pulse duration represents the key to locally process transparent materials within the bulk to induce modifications with feature sizes smaller than the wavelength of light [1, 2]. When focusing ultrashort laser pulses in the bulk of glass nonlinear absorption leads to extreme non-equilibrium states within a confined volume mediating the localized deposition of the laser pulse energy. Fused silica turned out as versatile platform to study the laser-induced modifications. Typically three different kinds are distinguished. First, isotropic refractive index changes allow for inscribing waveguides [3, 4] that may serve to realize complex photonic networks [5, 6]. Second, a confined micro-explosion within the focal volume may leave a region devoid of any material [7, 8] that can be used for data storage [9] or microfluidic purposes [10]. Finally, one of the key findings of laser materials processing is the local inscription of strong birefringence due to a sub-wavelength grating structure within an otherwise isotropic host material [11, 12]

Virtuelle Wirklichkeiten: Atmosphärisches Vergangenheitserleben im Digitalen Spiel

Atmosphären sind überall: am Arbeitsplatz, im Fußballstadion, vor dem knisternden Kaminfeuer. Sie prägen unsere Alltagssprache und sind ganz selbstverständlich gewordener Ausdruck dessen, wie wir uns in bestimmten Umgebungen befinden und wie wir diese empfinden. Ihr Einfluss ist weitreichend: Ästhetische Atmosphären sind eng verbunden mit einer gegenwärtigen erlebnisorientierten Geschichtskultur, deren Produkte und Praktiken behaupten, einen unmittelbaren Kontakt mit der Vergangenheit herzustellen. Mit den 'Vergangenheitsatmosphären' bietet der Autor erstmals einen Begriff an, um dieses Streben nach Unmittelbarkeit adäquat beschreiben zu können. Anhand tiefgehender Analysen der Digitalen Spiele "Anno 1800" (2019), "Assassin's Creed Syndicate" (2015) und "Dishonored: Die Maske des Zorns" (2012) wird der Begriff konturiert und die Produktivität einer an Theorien und Methoden der Public History, Game Studies und Phänomenologie geschulten Atmosphärenforschung unter Beweis gestellt