Robust Quantitative Comparative Statics for a Multimarket Paradox

We introduce a quantitative approach to comparative statics that allows to bound the maximum effect of an exogenous parameter change on a system's equilibrium. The motivation for this approach is a well known paradox in multimarket Cournot competition, where a positive price shock on a monopoly market may actually reduce the monopolist's profit. We use our approach to quantify for the first time the worst case profit reduction for multimarket oligopolies exposed to arbitrary positive price shocks. For markets with affine price functions and firms with convex cost technologies, we show that the relative profit loss of any firm is at most 25% no matter how many firms compete in the oligopoly. We further investigate the impact of positive price shocks on total profit of all firms as well as on social welfare. We find tight bounds also for these measures showing that total profit and social welfare decreases by at most 25% and 16.6%, respectively. Finally, we show that in our model, mixed, correlated and coarse correlated equilibria are essentially unique, thus, all our bounds apply to these game solutions as well.Comment: 23 pages, 1 figur

How does EU cohesion policy work? Evaluating its effects on fiscal outcome variables

The impact of EU Cohesion Policy has mainly been evaluated with regard to its growth effects. We extend the perspective by investigating the impact of EU Cohesion Policy on public investments and budget deficits in order to learn more about the channels through which this policy field works. Using a dataset of 27 EU countries for the time period 1982-2006, we find that EU Cohesion Policy payments do not cause public investments to increase significantly, which points to a crowding out of national investment. Moreover, the hypothesis that EU Cohesion Policy is used for the consolidation of public budgets cannot be completely rejected. --EU Cohesion Policy,public investment,public deficits,panel data

Which is the Right Dose of EU Cohesion Policy for Economic Growth?

The current empirical literature on the impact of EU Cohesion Policy on the economic growth rates of the European regions mainly relies on functional form assumptions. However, it is ex ante not clear which functional form is appropriate with regard to the relationship between structural funds pay- ments and regional economic growth. In order to avoid such assumptions, this paper applies the method of generalized propensity score (GPS) to a sample of 122 NUTS-1 and NUTS-2 EU-15 regions for the time period 1995{2005, which leads to the estimation of a dose-response function, as proposed by Hirano and Imbens (2004). Our results indicate that structural funds payments have a positive, but not statistically significant, impact on the regions' average three-year growth rates. This implies that it does not matter which \dose" of structural funds payments a region receives. --EU structural funds,economic growth,continuous treatment,dose-response function

Does EU Cohesion Policy Promote Growth? Evidence from Regional Data and Alternative Econometric Approaches

This paper analyses the growth e®ects of EU structural funds using a new panel dataset of 124 NUTS-1 / NUTS-2 regions over the time period 1995-2005. We extend the current literature with regard to at least three aspects: First of all, we extend the time period of investigation, using structural funds payments of the last Financial Perspective 2000{2006 that have not been analysed before. Second, we use more precise measures of structural funds by distinguishing between Objective 1, 2 and 3 payments and by investigating the impact of time lags more carefully. Third, we examine the robustness of our results by comparing different econometric approaches highlighting specific methodological problems. Apart from \classical" panel data methods like system GMM, we apply spatial panel econometric techniques. The empirical evidence indicates that the Objective 1 payments in particular have a positive and significant impact on growth, whereas Objective 2 and 3 payments negatively affect the regions' growth rates. Furthermore, our results show that the growth impact occurs with a time lag of approximately two to three years. --EU structural funds,economic growth,spatial econometrics

Do EU structural funds promote regional employment? Evidence from dynamic panel data models

Despite its rather broad goal of promoting “economic, social and territorial cohesion”, the existing literature has mainly focused on investigating the Cohesion Policy’s growth effects. This ignores the fact that part of the EU expenditures is directly aimed at reducing disparities in the employment sector. Against this background, the paper analyses the impact of EU structural funds on employment drawing on a panel dataset of 130 European NUTS regions over the time period 1999-2007. Compared to previous studies we (i) explicitly take into account the unambiguous theoretical propositions by testing the conditional impact of structural funds on the educational attainment of the regional labour supply, (ii) use more precise measures of structural funds for an extended time horizon and (iii) examine the robustness of our results by comparing different dynamic panel econometric approaches to control for heteroscedasticity, serial and spatial correlation as well as for endogeneity. Our results indicate that high-skilled population in particular benefits from EU structural funds. JEL Classification: R11, R12, C23, J20dynamic panel models, EU structural funds, regional employment effects, spatial panel econometrics

Solving Vertex Cover in Polynomial Time on Hyperbolic Random Graphs

The VertexCover problem is proven to be computationally hard in different ways: It is NP-complete to find an optimal solution and even NP-hard to find an approximation with reasonable factors. In contrast, recent experiments suggest that on many real-world networks the run time to solve VertexCover is way smaller than even the best known FPT-approaches can explain. Similarly, greedy algorithms deliver very good approximations to the optimal solution in practice. We link these observations to two properties that are observed in many real-world networks, namely a heterogeneous degree distribution and high clustering. To formalize these properties and explain the observed behavior, we analyze how a branch-and-reduce algorithm performs on hyperbolic random graphs, which have become increasingly popular for modeling real-world networks. In fact, we are able to show that the VertexCover problem on hyperbolic random graphs can be solved in polynomial time, with high probability. The proof relies on interesting structural properties of hyperbolic random graphs. Since these predictions of the model are interesting in their own right, we conducted experiments on real-world networks showing that these properties are also observed in practice. When utilizing the same structural properties in an adaptive greedy algorithm, further experiments suggest that, on real instances, this leads to better approximations than the standard greedy approach within reasonable time

The mechanics of stochastic slowdown in evolutionary games

We study the stochastic dynamics of evolutionary games, and focus on the so-called `stochastic slowdown' effect, previously observed in (Altrock et. al, 2010) for simple evolutionary dynamics. Slowdown here refers to the fact that a beneficial mutation may take longer to fixate than a neutral one. More precisely, the fixation time conditioned on the mutant taking over can show a maximum at intermediate selection strength. We show that this phenomenon is present in the prisoner's dilemma, and also discuss counterintuitive slowdown and speedup in coexistence games. In order to establish the microscopic origins of these phenomena, we calculate the average sojourn times. This allows us to identify the transient states which contribute most to the slowdown effect, and enables us to provide an understanding of slowdown in the takeover of a small group of cooperators by defectors: Defection spreads quickly initially, but the final steps to takeover can be delayed substantially. The analysis of coexistence games reveals even more intricate behavior. In small populations, the conditional average fixation time can show multiple extrema as a function of the selection strength, e.g., slowdown, speedup, and slowdown again. We classify two-player games with respect to the possibility to observe non-monotonic behavior of the conditional average fixation time as a function of selection strength.Comment: Accepted for publication in the Journal of Theoretical Biology. Includes changes after peer revie

Fast Solvers for Unsteady Thermal Fluid Structure Interaction

We consider time dependent thermal fluid structure interaction. The respective models are the compressible Navier-Stokes equations and the nonlinear heat equation. A partitioned coupling approach via a Dirichlet-Neumann method and a fixed point iteration is employed. As a refence solver a previously developed efficient time adaptive higher order time integration scheme is used. To improve upon this, we work on reducing the number of fixed point coupling iterations. Thus, first widely used vector extrapolation methods for convergence acceleration of the fixed point iteration are tested. In particular, Aitken relaxation, minimal polynomial extrapolation (MPE) and reduced rank extrapolation (RRE) are considered. Second, we explore the idea of extrapolation based on data given from the time integration and derive such methods for SDIRK2. While the vector extrapolation methods have no beneficial effects, the extrapolation methods allow to reduce the number of fixed point iterations further by up to a factor of two with linear extrapolation performing better than quadratic.Comment: 17 page