3,321 research outputs found
Tax-Transfer Systems in Europe: Between Efficiency, Redistribution and Stabilization
No full textThis thesis contains five empirical essays that aim at enriching the knowledge about European tax-transfer systems while also providing analyses concerned with concepts and developments that might become increasingly important for future policy design
Engineering Grid Markets
No full textGrids denote a promising concept to pool computer
resources for joint computations. Facing increasingly more complex
and demanding resources, Grids are deemed the solution to those
problems by a more efficient and flexible usage of already
existing resources. From a technical perspective Grid middleware
have made significant progress. While in former implementations it
was only possible to share idle resources (e.g. using Condor),
new Grid middleware allow advance reservation of resources that
are once committed not usable locally for the committed time
(e.g. GRAM in Globus Toolkit 4.0). Advance reservation thus
allows the sharing of not only idle resources but of all
designated resources.
The contribution of this paper is threefold. Firstly, this paper
derives a requirement list stemming from Grid applications that
need to be fulfilled by the market-based Grid. Secondly, the paper
compares related work with the above requirements. Thirdly, and
most importantly, this paper provides a fully-fledged market
mechanism that is tailored to the use in service-oriented Grids
Robert Neumann: Mit eigener Feder
No full textRobert Neumann (1897–1957, Austrian exiled author and Vicepresidet of the PEN International, was even a disputatious antifascist political writer. His essays, his letters and biograpical documents give a vivid portrait of the diversity of literary life in Germay and Austria (before 1933/after 1958) and of exile in England (1933–1958).Der österreichische Schriftsteller Robert Neumann (1897–1975), Exilant und Vizepräsident des PEN International, war auch ein streitbarer antifaschistischer Publizist. Seine politisch-literarischen Aufsätze, seine Briefe und biographischen Dokumente ergeben ein lebendiges und facettenreiches Bild des literarischen Lebens in Deutschland und Österreich (vor 1933/nach 1958) und des Exils in England (1933–1958)
Relative Haagerup property for arbitrary von Neumann algebras
No full textWe introduce the relative Haagerup approximation property for a unital, expected inclusion of arbitrary von Neumann algebras and show that if the smaller algebra is finite then the notion only depends on the inclusion itself, and not on the choice of the conditional expectation. Several variations of the definition are shown to be equivalent in this case, and in particular the approximating maps can be chosen to be unital and preserving the reference state. The concept is then applied to amalgamated free products of von Neumann algebras and used to deduce that the standard Haagerup property for a von Neumann algebra is stable under taking free products with amalgamation over finite-dimensional subalgebras. The general results are illustrated by examples coming from q-deformed Hecke-von Neumann algebras and von Neumann algebras of quantum orthogonal groups.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Analysi
A comparison of deflation and the balancing Neumann-Neumann preconditioner
No full textIn this paper we compare various preconditioners for the numerical solution of partial differential equations. We compare the well-known balancing Neumann Neumann preconditioner used in domain decomposition methods with a so-called deflation preconditioner. We prove that the effective condition number of the deflated preconditioned system is always, i.e. for all deflation vectors and all restrictions and prolongations, below the condition number of the system preconditioned by the balancing Neumann-Neumann preconditioner. Even more, we establish that both preconditioners lead to almost the same spectra. The zero eigenvalues of the deflation preconditioned system are replaced by eigenvalues which are one if the balancing Neumann-Neumann preconditioner is used. Moreover, we proved that the A-norm of the errors of the iterates build by the deflation preconditioner is always below the A-norm of the errors of the iterates build by the balancing Neumann-Neumann preconditioner. Additionally, the amount of work of one iteration of the de ation preconditioned system is less than the amount of work of one iteration of the balancing Neumann-Neumann preconditioned system. Finally, we establish that the deflation preconditioner and the balancing Neumann-Neumann preconditioner produces the same iterates if one uses certain starting vectors. Numerical results for porous media flows emphasize the theoretical results.Electrical Engineering, Mathematics and Computer Scienc
Carsten Holtmann and Dirk Neumann Market and Firm – Two Sides of a Coin 1
No full textElectronic markets are not just evolving they are designed. As such providing electronic trading venues is an entrepreneurial activity. The institutional approach followed here introduces a market operator as an economic player. As the entrepreneur charges fees for his service of operating an electronic market, the transaction cost savings incurred by information technology are essentially fully shifted to the market participants. As such the momentum predicted by the Electronic Market Hypothesis is limited in practice. The paper addresses this gap by deriving a conceptual framework, which reconciles the classical view on electronic markets with the entrepreneurial view.
Market engineering. A structured design process for electronic markets
No full textIn this book, the author provides a complete process for electronic markets design together with the required en-gineering methods. As such the book is unique applying tech-niques from engineering design to modern Information Systems and Economics. Mr. Neumann succeeds in presenting a generic but coherent approach that is an indispensable aid in designing markets
Analysis of different MMAS ACO algorithms on unimodal functions and plateaus
No full textRecently, the first rigorous runtime analyses of ACO algorithms appeared, covering variants of the MAX - MIN ant system and their runtime on pseudo-Boolean functions. Interestingly, a variant called 1-ANT is very sensitive to the evaporation factor while Gutjahr and Sebastiani proved partly opposite results for their variant MMASbs. These algorithms differ in their pheromone update mechanisms and, moreover, 1-ANT accepts equally fit solutions in contrast to MMASbs. By analyzing variants of MMASbs, we prove that the different behavior of 1-ANT and MMASbs results from the different pheromone update mechanisms. Building upon results by Gutjahr and Sebastiani, we extend their analyses of MMASbs to the class of unimodal functions and show improved results for test functions using new and specialized techniques; in particular, we present new lower bounds. Finally, we compare MMASbs with a variant that also accepts equally fit solutions as this enables the exploration of plateaus. For well-known plateau functions we prove that this drastically reduces the optimization time. Our findings are complemented by experiments that support our asymptotic analyses and yield additional insights. © The Author(s) 2008.Frank Neumann, Dirk Sudholt, Carsten Wit
A fixed budget analysis of randomized search heuristics for the traveling salesperson problem
No full textRandomized Search heuristics are frequently applied to NP-hard combinatorial optimization problems. The runtime analysis of randomized search heuristics has contributed tremendously to their theoretical understanding. Recently, randomized search heuristics have been examined regarding their achievable progress within a fixed time budget. We follow this approach and present a first fixed budget runtime analysis for a NP-hard combinatorial optimization problem. We consider the well-known Traveling Salesperson problem (TSP) and analyze the fitness increase that randomized search heuristics are able to achieve within a given fixed budget.Samadhi Nallaperuma, Frank Neumann, Dirk Sudhol
Computational complexity of ant colony optimization and its hybridization with local search
No full textThe computational complexity of ant colony optimization (ACO) is a new and rapidly growing research area. The finite-time dynamics of ACO algorithms is assessed with mathematical rigor using bounds on the (expected) time until an ACO algorithm finds a global optimum. We review previous results in this area and introduce the reader into common analysis methods. These techniques are then applied to obtain bounds for different ACO algorithms on classes of pseudo-Boolean problems. The resulting runtime bounds are further used to clarify important design issues from a theoretical perspective. We deal with the question whether the current best-so-far solution should be replaced by new solutions with the same quality. Afterwards, we discuss the hybridization of ACO with local search and present examples where introducing local search leads to a tremendous speed-up and to a dramatic loss in performance, respectively.Frank Neumann, Dirk Sudholt, and Carsten Wit
- …
