On the Power of Advice and Randomization for Online Bipartite Matching

While randomized online algorithms have access to a sequence of uniform random bits, deterministic online algorithms with advice have access to a sequence of advice bits, i.e., bits that are set by an all powerful oracle prior to the processing of the request sequence. Advice bits are at least as helpful as random bits, but how helpful are they? In this work, we investigate the power of advice bits and random bits for online maximum bipartite matching (MBM). The well-known Karp-Vazirani-Vazirani algorithm is an optimal randomized $(1-\frac{1}{e})$-competitive algorithm for \textsc{MBM} that requires access to $\Theta(n \log n)$ uniform random bits. We show that $\Omega(\log(\frac{1}{\epsilon}) n)$ advice bits are necessary and $O(\frac{1}{\epsilon^5} n)$ sufficient in order to obtain a $(1-\epsilon)$-competitive deterministic advice algorithm. Furthermore, for a large natural class of deterministic advice algorithms, we prove that $\Omega(\log \log \log n)$ advice bits are required in order to improve on the $\frac{1}{2}$-competitiveness of the best deterministic online algorithm, while it is known that $O(\log n)$ bits are sufficient. Last, we give a randomized online algorithm that uses $c n$ random bits, for integers $c \ge 1$, and a competitive ratio that approaches $1-\frac{1}{e}$ very quickly as $c$ is increasing. For example if $c = 10$, then the difference between $1-\frac{1}{e}$ and the achieved competitive ratio is less than $0.0002$

LAND MARKETS IN AGENT BASED MODELS OF STRUCTURAL CHANGE

Replaced with revised version of paper 02/22/08.Land Economics/Use, Research Methods/ Statistical Methods,

WINNERS AND LOSERS OF POLICY CHANGES – WHAT IS THE ROLE OF STRUCTURAL CHANGE?

In this paper several decoupling options are evaluated concerning their impact on structural change especially on farm incomes and their surviving. Therefore, the agent-based model AgriPoliS was used and extended to account the income of leaving farms. This enables the comparison of future incomes of leaving and surviving farms to find out whether leaving farms are losers or not. The disaggregated analysis of farms’ household incomes showed that leaving farmers even benefit from their decision in case that enough off-farm jobs are available. Losers are farms that would have left agriculture under conditions of the Agenda 2000. After decoupling they stay in the sector and cannot increase their income as much as under Agenda conditions. Furthermore, the analysis displayed a persistence of farms in the sector despite it would have been more profitable for them to quit agriculture.Structural change, decoupling, agent-based modeling, Common Agricultural Policy, Agricultural and Food Policy, Consumer/Household Economics, Farm Management,

Analysis of the sedimentary characteristics of the tees estuary using remote sensing and GIS techniques

This thesis examines the ability of airborne remotely sensed data to provide quantitative information about the characteristics of intertidal sediments. The research was undertaken on Seal Sands in the Tees estuary, UK, and the airborne imagery was acquired by the Natural Environment Research Council (NERC) using a Daedalus 1268 11 channel scanning radiometer. The research focused upon establishing calibration and correction procedures for the airborne imagery as well as developing GIS techniques to process and analyze the data. A database was produced for the National Nature Reserve of Seal Sands to integrate remotely sensed imagery data, primary data from fieldwork (particle size analysis) and digital map data. Quantitative analysis of the relationship between radiance and particle size characteristics was undertaken. Results show that a multiple regression model is able to predict sand fractions in intertidal sediments and explain over 70% of the variance in radiance data. GIS techniques have facilitated predictions of the ATM data and particle size analysis of the intertidal sediments, sediment interpolation, and spatial patterns of birds' feeding behaviour. In addition, a digital elevation model (DEM) was established to investigate the relationship of sediment distribution to topography. Although limited to a single study area, the integrated approach employed in this research should be of use in monitoring estuarine environments elsewhere

Metellus and the Head of Sertorius

Sin resume

Semantic 3D Reconstruction with Finite Element Bases

We propose a novel framework for the discretisation of multi-label problems on arbitrary, continuous domains. Our work bridges the gap between general FEM discretisations, and labeling problems that arise in a variety of computer vision tasks, including for instance those derived from the generalised Potts model. Starting from the popular formulation of labeling as a convex relaxation by functional lifting, we show that FEM discretisation is valid for the most general case, where the regulariser is anisotropic and non-metric. While our findings are generic and applicable to different vision problems, we demonstrate their practical implementation in the context of semantic 3D reconstruction, where such regularisers have proved particularly beneficial. The proposed FEM approach leads to a smaller memory footprint as well as faster computation, and it constitutes a very simple way to enable variable, adaptive resolution within the same model

Non-abelian gerbes and some applications in string theory

We review a systematic construction of the 2-stack of bundle gerbes via descent, and extend it to non-abelian gerbes. We review the role of non-abelian gerbes in orientifold sigma models, for the anomaly cancellation in supersymmetric sigma models, and in a geometric description of so-called non-geometric T-duals.Comment: Contribution to "Particles, String and the Early Universe - Research Results of the Collaborative Research Centre SFB 676 in Hamburg

EXPLORING THE ROLE OF SUCCESSION PATTERNS IN CENTRAL AND EASTERN EUROPEAN'S DUALISTIC FARM STRUCTURES

This paper analyses the interplay between farm adjustments on individual farms in dualistic farm structures over time using an agent-based simulation approach. In particular, explore the development of individual farms when there are off-farm work opportunities and different propensities of younger farm successors to take over the farm. Results show that despite of large numbers of individual farms leaving agriculture, the impacts on land use, production, and income are independent on different propensities to take over a farm.dualistic farm structures, individual farms, generation change, succession, Farm Management, Institutional and Behavioral Economics,