Predicting Destinations by Nearest Neighbor Search on Training Vessel Routes

The DEBS Grand Challenge 2018 is set in the context of maritime route prediction. Vessel routes are modeled as streams of Automatic Identification System (AIS) data points selected from real-world tracking data. The challenge requires to correctly estimate the destination ports and arrival times of vessel trips, as early as possible. Our proposed solution partitions the training vessel routes by reported destination port and uses a nearest neighbor search to find the training routes that are closer to the query AIS point. Particular improvements have been included as well, such as a way to avoid changing the predicted ports frequently within one query route and automating the parameters tuning by the use of a genetic algorithm. This leads to significant improvements on the final score

Explicit linear kernels via dynamic programming

Several algorithmic meta-theorems on kernelization have appeared in the last years, starting with the result of Bodlaender et al. [FOCS 2009] on graphs of bounded genus, then generalized by Fomin et al. [SODA 2010] to graphs excluding a fixed minor, and by Kim et al. [ICALP 2013] to graphs excluding a fixed topological minor. Typically, these results guarantee the existence of linear or polynomial kernels on sparse graph classes for problems satisfying some generic conditions but, mainly due to their generality, it is not clear how to derive from them constructive kernels with explicit constants. In this paper we make a step toward a fully constructive meta-kernelization theory on sparse graphs. Our approach is based on a more explicit protrusion replacement machinery that, instead of expressibility in CMSO logic, uses dynamic programming, which allows us to find an explicit upper bound on the size of the derived kernels. We demonstrate the usefulness of our techniques by providing the first explicit linear kernels for $r$-Dominating Set and $r$-Scattered Set on apex-minor-free graphs, and for Planar-\mathcal{F}-Deletion on graphs excluding a fixed (topological) minor in the case where all the graphs in \mathcal{F} are connected.Comment: 32 page

Momentum dependence of the superconducting gap and in-gap states in MgB2 multi-band superconductor

We use tunable laser based Angle Resolved Photoemission Spectroscopy to study the electronic structure of the multi-band superconductor, MgB2. These results form the base line for detailed studies of superconductivity in multi-band systems. We find that the magnitude of the superconducting gap on both sigma bands follows a BCS-like variation with temperature with Delta0 ~7 meV. The value of the gap is isotropic within experimental uncertainty and in agreement with pure a s-wave pairing symmetry. We also observe in-gap states confined to kF of the sigma band that occur at some locations of the sample surface. The energy of this excitation, ~3 meV, is inconsistent with scattering from the pi band.Comment: 6 pages, 4 figure

Essays in public economics and on equality of opportunity

The dissertation consists of four independent empirical essays. The first chapter analyzes to what extent firms adjust their investment plans to higher tax rates, based on municipality level variation in business tax rates in Germany. The further chapters deal with the measurement of equality of opportunity. Chapter 2 develops a new approach to measuring social mobility in Germany. Chapter 3 characterizes equality of opportunity in the joint distribution of income and wealth in the USA. The final chapter documents new relationships between socio-economic status, career preferences, and future income and labor market participation. The results suggest that such career preferences may play an important role in the intergenerational transmission of socio-economic status.Die Dissertation besteht aus vier eigenständigen empirischen Aufsätzen. Das erste Kapitel untersucht auf der Grundlage von Gewerbesteuererhöhungen auf Gemeindeebene in Deutschland, inwieweit Unternehmen ihre Investitionspläne an höhere Steuersätze anpassen. Die weiteren Kapitel befassen sich mit der Messung von Chancengerechtigkeit. Kapitel 2 entwickelt einen neuen Ansatz zur Messung von sozialer Mobilität in Deutschland. Kapitel 3 charakterisiert Chancengerechtigkeit in der gemeinsamen Verteilung von Einkommen und Vermögen in den USA. Das letzte Kapitel dokumentiert neue Zusammenhänge zwischen sozioökonomischem Status, Präferenzen bei der Berufswahl, und zukünftigen Einkommen und Arbeitsmarktbeteiligung. Die Ergebnisse deuten darauf hin, dass Berufswahlpräferenzen eine wichtige Rolle bei der generationsübergreifenden Weitergabe von sozioökonomischem Status spielen