Results for "Christoph Dürr"

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The expanding search ratio of a graphFeb 18 2016We study the problem of searching for a hidden target in an environment that is modeled by an edge-weighted graph. A sequence of edges is chosen starting from a given {\em root} vertex such that each edge is adjacent to a previously chosen edge. This ... More
The expanding search ratio of a graphFeb 18 2016Aug 01 2017We study the problem of searching for a hidden target in an environment that is modeled by an edge-weighted graph. A sequence of edges is chosen starting from a given root vertex such that each edge is adjacent to a previously chosen edge. This search ... More
Smooth Inequalities and Equilibrium Inefficiency in Scheduling GamesFeb 20 2012We study coordination mechanisms for Scheduling Games (with unrelated machines). In these games, each job represents a player, who needs to choose a machine for its execution, and intends to complete earliest possible. Our goal is to design scheduling ... More
Mechanism design for aggregating energy consumption and quality of service in speed scaling schedulingApr 14 2015Jul 10 2017We consider a strategic game, where players submit jobs to a machine that executes all jobs in a way that minimizes energy while respecting the given deadlines. The energy consumption is then charged to the players in some way. Each player wants to minimize ... More
Scheduling under dynamic speed-scaling for minimizing weighted completion time and energy consumptionMay 29 2018Since a few years there is an increasing interest in minimizing the energy consumption of computing systems. However in a shared computing system, users want to optimize their experienced quality of service, at the price of a high energy consumption. ... More
Mechanism design for aggregating energy consumption and quality of service in speed scaling schedulingApr 14 2015We consider a strategic game, where players submit jobs to a machine that executes all jobs in a way that minimizes energy while respecting the given eadlines. The energy consumption is then charged to the players in some way. Each player wants to minimize ... More
On the Power of Advice and Randomization for Online Bipartite MatchingFeb 23 2016Jun 21 2016While 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 ... More
Best-of-two-worlds analysis of online searchOct 18 2018In search problems, a mobile searcher seeks to locate a target that hides in some unknown position of the environment. Such problems are typically considered to be of an on-line nature, in that the input is unknown to the searcher, and the performance ... More
Online Maximum Matching with RecourseJan 10 2018May 07 2018We study the online maximum matching problem in a model in which the edges are associated with a known recourse parameter $k$. An online algorithm for this problem has to maintain a valid matching while edges of the underlying graph are presented one ... More
Scheduling with Explorable UncertaintySep 08 2017We introduce a novel model for scheduling with explorable uncertainty. In this model, the processing time of a job can potentially be reduced (by an a priori unknown amount) by testing the job. Testing a job $j$ takes one unit of time and may reduce its ... More
Online Computation with Untrusted AdviceMay 14 2019The advice model of online computation captures the setting in which the online algorithm is given some partial information concerning the request sequence. This paradigm allows to establish tradeoffs between the amount of this additional information ... More
The local-global conjecture for scheduling with non-linear costApr 23 2013Dec 21 2015We consider the classical scheduling problem on a single machine, on which we need to schedule sequentially $n$ given jobs. Every job $j$ has a processing time $p_j$ and a priority weight $w_j$, and for a given schedule a completion time $C_j$. In this ... More
Enabling Interactive Mobile Simulations Through Distributed Reduced ModelsFeb 14 2018Currently, various hardware and software companies are developing augmented reality devices, most prominently Microsoft with its Hololens. Besides gaming, such devices can be used for serious pervasive applications, like interactive mobile simulations ... More
Non-monotone DR-submodular Maximization: Approximation and Regret GuaranteesMay 23 2019Diminishing-returns (DR) submodular optimization is an important field with many real-world applications in machine learning, economics and communication systems. It captures a subclass of non-convex optimization that provides both practical and theoretical ... More
Speed scaling with power down scheduling for agreeable deadlinesNov 15 2011Oct 19 2012We consider the problem of scheduling on a single processor a given set of n jobs. Each job j has a workload w_j and a release time r_j. The processor can vary its speed and hibernate to reduce energy consumption. In a schedule minimizing overall consumed ... More
A Note on NP-Hardness of Preemptive Mean Flow-Time Scheduling for Parallel MachinesApr 22 2014In the paper "The complexity of mean flow time scheduling problems with release times", by Baptiste, Brucker, Chrobak, D\"urr, Kravchenko and Sourd, the authors claimed to prove strong NP-hardness of the scheduling problem $P|pmtn,r_j|\sum C_j$, namely ... More
Coherent Logic Gate for Light Pulses based on Storage in a Bose-Einstein CondensateNov 30 2012A classical logic gate connecting input and output light pulses is demonstrated. The gate operation is based on three steps: First, two incoming light pulses are stored in a Bose-Einstein condensate, second, atomic four-wave mixing generates a new matter ... More
The triangle scheduling problemFeb 13 2016May 01 2016This paper introduces a novel scheduling problem, where jobs occupy a triangular shape on the time line. This problem is motivated by scheduling jobs with different criticality levels. A measure is introduced, namely the binary tree ratio. It is shown ... More
Bose-Einstein condensate as a quantum memory for a photonic polarization qubitDec 20 2011Feb 14 2012A scheme based on electromagnetically induced transparency is used to store light in a Bose-Einstein condensate. In this process, a photonic polarization qubit is stored in atomic Zeeman states. The performance of the storage process is characterized ... More
The interval ordering problemDec 02 2011For a given set of intervals on the real line, we consider the problem of ordering the intervals with the goal of minimizing an objective function that depends on the exposed interval pieces (that is, the pieces that are not covered by earlier intervals ... More
Lattice QCD data versus Chiral Perturbation Theory: the case of $M_π$Sep 26 2002Sep 27 2002I present a selection of recent lattice data by major collaborations for the pseudo-Goldstone boson masses in full ($N_f=2$) QCD, where the valence quarks are chosen exactly degenerate with the sea quarks. At least the more chiral points should be consistent ... More
Simple check of the vacuum structure in full QCD lattice simulationsAug 13 2001Given the increasing availability of lattice data for (unquenched) QCD with $N_f=2$, it is worth while to check whether the generated vacuum significantly deviates from the quenched one. I discuss a specific attempt to do this on the basis of topological ... More
Study of the Leutwyler-Smilga regimes: Lessons for full QCD simulationsOct 22 2000Nov 07 2000Some key points out of my recent study of the characteristic features of the small ($x \ll 1$), intermediate ($x \simeq 1$) and large ($x \gg 1$) Leutwyler-Smilga regimes for QCD-type theories in a finite volume ($x = V \Sigma m$) are presented, and a ... More
Theoretical Aspects of Topologically Unquenched QCDSep 08 1999I give an outline of my proposal to take the QCD functional determinant in lattice simulations partially into account: The determinant is split into two factors, the factor referring to a standard background in each topological sector is kept exactly, ... More
Increased Dimensionality of Raman Cooling in a Slightly Nonorthogonal Optical LatticeApr 17 2018Jul 02 2018We experimentally study the effect of a slight nonorthogonality in a two-dimensional optical lattice onto resolved-sideband Raman cooling. We find that when the trap frequencies of the two lattice directions are equal, the trap frequencies of the combined ... More
The phase transition in the multiflavour Schwinger modelSep 12 2000A summary is given of a quantization of the multiflavour Schwinger model on a finite-temperature cylinder with chirality-breaking boundary conditions at its spatial ends, and it is shown that the analytic expression for the chiral condensate implies that ... More
QCD in a finite box: Numerical test studies in the three Leutwyler-Smilga regimesAug 30 2000Nov 07 2000The Leutwyler-Smilga prediction regarding the (ir)relevance of the global topological charge for QCD in a finite box is subject to a test. To this end the lattice version of a suitably chosen analogue (massive 2-flavour Schwinger model) is analyzed in ... More
Time Evolution of the External Field Problem in QEDMay 30 2009May 25 2010We construct the time-evolution for the second quantized Dirac equation subject to a smooth, compactly supported, time dependent electromagnetic potential and identify the degrees of freedom involved. Earlier works on this (e.g. Ruijsenaars) observed ... More
Magnetization DynamicsOct 10 2018Magnetism primarily describes the physics and materials science of systems presenting a magnetization -- a macroscopic order parameter characterizing electron angular momentum. The order parameter is associated with the electronic exchange interactions, ... More
Introduction to Physical Implementations of Quantum Information ProcessingMar 01 2013This was a contribution to the lecture notes on the 44th IFF Spring School held at Forschungszentrum J\"ulich in 2013 on "Quantum Information Processing". The school as a whole had a strong focus on solid state systems. It was the purpose of this contribution ... More
Gauge action improvement and smearingSep 23 2004Dec 28 2005The effect of repeatedly smearing SU(3) gauge configurations is investigated. Six gauge actions (Wilson, Symanzik, Iwasaki, DBW2, Beinlich-Karsch-Laermann, Langfeld; combined with a direct SU(3)-overrelaxation step) and three smearings (APE, HYP, EXP) ... More
Aspects of Quasi-Phasestructure of the Schwinger Model on a Cylinder with Broken Chiral SymmetryMay 19 1998Oct 05 1998We consider the N_f-flavour Schwinger Model on a thermal cylinder of circumference $\beta=1/T$ and of finite spatial length $L$. On the boundaries $x^1=0$ and $x^1=L$ the fields are subject to an element of a one-dimensional class of bag-inspired boundary ... More
A Flat and Scalable Data Center Network Topology Based on De Bruijn GraphsOct 11 2016Due to the requirement of hosting tens of thousands of hosts in today's data centers, data center networks strive for scalability and high throughput on the one hand. On the other hand, the cost for networking hardware should be minimized. Consequently, ... More
Prospects of `Topologically Unquenched QCD' from a study of the analogous importance sampling method in the massive Schwinger modelSep 08 1999I give a quick summary of my proposal for simulating an improvement on quenched QCD with dynamical fermions which interact with the gluon configuration only via the topological index of the latter. It amounts to include only the topological part of the ... More
Topology and pion correlators -- a study in the N_f=2 Schwinger modelOct 22 2001I readdress the issue whether the topological charge of the gauge background has an influence on a hadronic observable. To this end pion correlators in the Schwinger model with 2 dynamical flavours are determined on subensembles with a fixed topological ... More
Proposal for Topologically Unquenched QCDJan 06 1998Jan 25 1999A proposal is presented for simulating an improvement on quenched QCD with dynamical fermions which interact with the gluon configuration only via the topological index of the latter. Strengths and shortcomings of the method are discussed and it is argued ... More
The diffeomorphism supergroup of a finite-dimensional supermanifoldApr 17 2009Sep 24 2009Using the categorical description of supergeometry we give an explicit construction of the diffeomorphism supergroup of a compact finite-dimensional supermanifold. The construction provides the diffeomorphism supergroup with the structure of a Frechet ... More
Equivalences of Smooth and Continuous Principal Bundles with Infinite-Dimensional Structure GroupApr 06 2006Jun 28 2012Let K be a a Lie group, modeled on a locally convex space, and M a finite-dimensional paracompact manifold with corners. We show that each continuous principal K-bundle over M is continuously equivalent to a smooth one and that two smooth principal K-bundles ... More
Local phase damping of single qubits sets an upper bound on the phase damping rate of entangled statesNov 30 2011Jan 27 2012I derive an inequality in which the phase damping rates of single qubits set an upper bound for the phase damping rate of entangled states of many qubits. The derivation is based on two assumptions: first, that the phase damping can be described by a ... More
Topological susceptibility in full QCD: lattice results versus the prediction from the QCD partition function with granularityMar 14 2001Jun 29 2001Recent lattice data from CP-PACS, UKQCD, SESAM/TXL and the Pisa group regarding the quark mass dependence of the topological susceptibility in 2-flavour QCD are compared to each other and to theoretical expectations. The latter get specified by referring ... More
Topologically Unquenched QCD: Prospects from an explorative study in 2-flavour QED(2)Mar 22 2000May 11 2000The concept of simulating a variant of QCD with sea quarks which interact with the gluon configuration only via global gluonic quantities like $\int F\tilde F dx$ and $\int FF dx$ is tested for the case of the massive 2-flavour Schwinger model. It is ... More
M_pi^2 versus m_q: comparing CP-PACS and UKQCD data to Chiral Perturbation TheoryAug 26 2002Mar 21 2003I present a selection of CP-PACS and UKQCD data for the pseudo-Goldstone masses in $N_f=2$ QCD with doubly degenerate quarks. At least the more chiral points should be consistent with Chiral Perturbation Theory for the latter to be useful in an extrapolation ... More
Testing the Leutwyler-Smilga prediction regarding the global topological charge distribution on the latticeSep 12 2000I give a sketch of my recent attempt to test the prediction by Leutwyler and Smilga according to which, for QCD in a finite box with $N_{f} \geq 2$, the combination $x = V \Sigma m$ indicates whether the net topological charge of the gauge background ... More
Lower Bounds for Existential Pebble Games and k-Consistency TestsMay 03 2012Oct 07 2013The existential k-pebble game characterizes the expressive power of the existential-positive k-variable fragment of first-order logic on finite structures. The winner of the existential k-pebble game on two given finite structures can be determined in ... More
Symmetric union presentations for 2-bridge ribbon knotsFeb 17 2006Symmetric unions have been defined as generalizations of Kinoshita-Terasaka's construction in 1957. They are given by diagrams which look like the connected sum of a knot and its mirror image with additional twist tangles inserted near the symmetry axis. ... More
Supersymmetric leptogenesis and light hidden sectorsSep 29 2010Thermal leptogenesis and supergravity are attractive scenarios for physics beyond the standard model. However, it is well known that the super-weak interaction of the gravitino often leads to problems with primordial nucleosynthesis in the standard scenario ... More
Computational Complexity of Iterated Maps on the Interval (Extended Abstract)Jun 02 2010The exact computation of orbits of discrete dynamical systems on the interval is considered. Therefore, a multiple-precision floating point approach based on error analysis is chosen and a general algorithm is presented. The correctness of the algorithm ... More
Magnetic field amplification in turbulent astrophysical plasmasOct 26 2016Magnetic fields play an important role in astrophysical accretion discs, and in the interstellar and intergalactic medium. They drive jets, suppress fragmentation in star-forming clouds and can have a significant impact on the accretion rate of stars. ... More
D-branes in group manifolds and flux stabilizationDec 06 2000We consider D-branes in group manifolds, from the point of view of open strings and using the Born-Infeld action on the brane worldvolume. D-branes correspond to certain integral (twined) conjugacy classes. We explain the integrality condition on the ... More
Information theory in molecular biologyMay 05 2004This article introduces the physics of information in the context of molecular biology and genomics. Entropy and information, the two central concepts of Shannon's theory of information and communication, are often confused with each other but play transparent ... More
The use of information theory in evolutionary biologyDec 16 2011Information is a key concept in evolutionary biology. Information is stored in biological organism's genomes, and used to generate the organism as well as to maintain and control it. Information is also "that which evolves". When a population adapts to ... More
Luminosity of young Jupiters revisited. Massive cores make hot planetsJun 24 2013The intrinsic luminosity of young Jupiters is of high interest for planet formation theory. It is an observable quantity that is determined by important physical mechanisms during formation, namely the accretion shock structure, and even more fundamentally, ... More
Simple Type Theory as Framework for Combining LogicsApr 30 2010Simple type theory is suited as framework for combining classical and non-classical logics. This claim is based on the observation that various prominent logics, including (quantified) multimodal logics and intuitionistic logics, can be elegantly embedded ... More
Shaping tail dependencies by nesting box copulasJun 26 2009Aug 11 2009We introduce a family of copulas which are locally piecewise uniform in the interior of the unit cube of any given dimension. Within that family, the simultaneous control of tail dependencies of all projections to faces of the cube is possible and we ... More
Seven-Dimensional Super-Yang-Mills Theory in N=1 SuperfieldsFeb 01 2011We give a gauge-covariant formulation of seven-dimensional super-Yang-Mills theory in terms of N=1 superfields. Furthermore, we show that five and seven dimensions are the only cases where such a formulation exists by analysing the interplay of Lorentz ... More
Algebraic Multigrid for Disordered Systems and Lattice Gauge TheoriesNov 30 2000The construction of multigrid operators for disordered linear lattice operators, in particular the fermion matrix in lattice gauge theories, by means of algebraic multigrid and block LU decomposition is discussed. In this formalism, the effective coarse-grid ... More
Geometrical aspects of qudits concerning Bell inequalitiesJul 07 2009The aim of this thesis is to investigate quantum entanglement and quantum nonlocality of bipartite finite-dimensional systems (bipartite qudits). Entanglement is one of the most fascinating non-classical features of quantum theory, and besides its impact ... More
INTEGRAL: status of the mission - after 10 yearsDec 18 2012The ESA gamma-ray observatory INTEGRAL, launched on 17 October 2002, continues to produce a wealth of discoveries and new results on compact high energy Galactic objects,nuclear gamma-ray line emission, diffuse line and continuum emission, cosmic background ... More
INTEGRAL - status of the missionOct 27 2011The ESA gamma-ray observatory INTEGRAL, launched on 17 October 2002, continues to produce a wealth of discoveries and new results on compact high energy Galactic objects, nuclear gamma-ray line emission, diffuse line and continuum emission, cosmic background ... More
Survival probabilities of some iterated processesJun 15 2011Jul 19 2011We study the asymptotic behaviour of the probability that a stochastic process $(Z_t)_{t \geq 0}$ does not exceed a constant barrier up to time $T$ (the so called survival probability) when Z is the composition of two independent processes $(X_t)_{t \in ... More
Natural Entanglement in Bose-Einstein CondensatesOct 18 2001Every Bose-Einstein condensate is in a highly entangled state, as a consequence of the fact that the particles in a condensate are distributed over space in a coherent way. It is proved that any two regions within a condensate of finite particle number ... More
Analysis of discontinuous Galerkin dual-primal isogeometric tearing and interconnecting methodsNov 30 2016In this paper, we present the analysis of the discontinuous Galerkin dual-primal isogeometric tearing and interconnecting method (dG-IETI-DP) for the two-dimensional case where we only consider vertex primal variables. The dG-IETI-DP method is a combination ... More
The maximal excess charge for a family of density-matrix-functional theories including Hartree-Fock and Müller theoriesSep 20 2016We will give a proof that the maximal excess charge for an atom described by a family of density-matrix-functionals, which includes Hartree-Fock and M\"uller theories, is bounded by an universal constant. We will use the new technique introduced by Frank ... More
On the existence of regular vectorsOct 29 2015Nov 06 2015Let $G$ be a locally convex Lie group and $\pi:G \to \mathrm{U}(\mathcal{H})$ be a continuous unitary representation. $\pi$ is called smooth if the space of $\pi$-smooth vectors $\mathcal{H}^\infty\subset \mathcal{H}$ is dense. In this article we show ... More
Fast Multiplication of Large Integers: Implementation and Analysis of the DKSS AlgorithmMar 17 2015The Sch\"onhage-Strassen algorithm (SSA) is the de-facto standard for multiplication of large integers. For $N$-bit numbers it has a time bound of $O(N \cdot \log N \cdot \log \log N)$. De, Kurur, Saha and Saptharishi (DKSS) presented an asymptotically ... More
Polar codes in quantum information theoryJan 15 2015Polar codes are the first capacity achieving and efficiently implementable codes for classical communication. Recently they have also been generalized to communication over classical-quantum and quantum channels. In this work we present our recent results ... More
Inefficient star formation through turbulence, magnetic fields and feedbackApr 14 2015May 15 2015Star formation is inefficient. Only a few percent of the available gas in molecular clouds forms stars, leading to the observed low star formation rate (SFR). The same holds when averaged over many molecular clouds, such that the SFR of whole galaxies ... More
Effective time-reversal via periodic shakingJun 15 2012For a periodically shaken optical lattice, effective time-reversal is investigated numerically. For interacting ultra-cold atoms, the scheme of [J. Phys. B 45, 021002 (2012)] involves a quasi-instantaneous change of both the shaking-amplitude and the ... More
Computing with Logic as Operator Elimination: The ToyElim SystemAug 24 2011A prototype system is described whose core functionality is, based on propositional logic, the elimination of second-order operators, such as Boolean quantifiers and operators for projection, forgetting and circumscription. This approach allows to express ... More
Schmüdgen's theorem and results of positivityNov 17 2014This is a translation of a final paper. It contains proofs of some well-known Positivstellens\"atze. The approach in this paper differs in two respects from presentations in literature. We use the Stone-Weierstrass Theorem directly to prove an inductive ... More
On a problem of Bourgain concerning the $L^1$-norm of exponential sumsNov 20 2012Bourgain posed the problem of calculating $$ \Sigma = \sup_{n \geq 1} ~\sup_{k_1 <... < k_n} \frac{1}{\sqrt{n}}\| \sum_{j=1}^n e^{2 \pi i k_j \theta}\|_{L^1([0,1])}. $$ It is clear that $\Sigma \leq 1$; beyond that, determining whether $\Sigma < 1$ or ... More
Exponential state estimation, entropy and Lyapunov exponentsMay 10 2016May 05 2017In this paper we study the notion of estimation entropy recently established by Liberzon and Mitra. This quantity measures the smallest rate of information about the state of a dynamical system above which an exponential state estimation with a given ... More
Metric Entropy of Nonautonomous Dynamical SystemsApr 21 2013Jul 16 2013We introduce the notion of metric entropy for a nonautonomous dynamical system given by a sequence of probability spaces and a sequence of measure-preserving maps between these spaces. This notion generalizes the classical concept of metric entropy established ... More
The role of the patch test in 2D atomistic-to-continuum coupling methodsJan 27 2011Mar 15 2011For a general class of atomistic-to-continuum coupling methods, coupling multi-body interatomic potentials with a P1-finite element discretisation of Cauchy--Born nonlinear elasticity, this paper adresses the question whether patch test consistency (or, ... More
Autocorrelation type functions for big and dirty data seriesNov 14 2014Dec 23 2014One form of big data are signals - time series of consecutive values. In physical experiments, billions of values can now be measured within a second. Signals of heart and brain in intensive care, as well as seismic waves, are measured with 100 up to ... More
Finite orbits in multivalued maps and Bernoulli convolutionsSep 29 2015Nov 28 2017Bernoulli convolutions are certain measures on the unit interval depending on a parameter $\beta$ between 1 and 2. In spite of their simple definition, they are not yet well understood. We study their two-dimensional density which exists by a theorem ... More
SWiM -- A Semantic Wiki for Mathematical Knowledge ManagementMar 26 2010SWiM is a semantic wiki for collaboratively building, editing and browsing mathematical knowledge represented in the domain-specific structural semantic markup language OMDoc. It motivates users to contribute to collections of mathematical knowledge by ... More
wiki.openmath.org - how it works, how you can participateMar 26 2010At http://wiki.openmath.org, the OpenMath 2 and 3 Content Dictionaries are accessible via a semantic wiki interface, powered by the SWiM system. We shortly introduce the inner workings of the system, then describe how to use it, and conclude with first ... More
Normal numbers and normality measureFeb 08 2013The normality measure $\mathcal{N}$ has been introduced by Mauduit and S{\'a}rk{\"o}zy in order to describe the pseudorandomness properties of finite binary sequences. Alon, Kohayakawa, Mauduit, Moreira and R{\"o}dl proved that the minimal possible value ... More
Uniformly hyperbolic control theoryNov 25 2015Jan 13 2017This paper gives a summary of a body of work at the intersection of control theory and smooth nonlinear dynamics. The main idea is to transfer the concept of uniform hyperbolicity, central to the theory of smooth dynamical systems, to control-affine systems. ... More
Positive solutions of some parabolic system with cross-diffusion and nonlocal initial conditionsNov 15 2010The paper is concerned with a system consisting of two coupled nonlinear parabolic equations with a cross-diffusion term, where the solutions at positive times define the initial states. The equations arise as steady state equations of an age-structured ... More
On the limit distribution of the normality measure of random binary sequencesJan 28 2013Apr 03 2014We prove the existence of a limit distribution for the normalized normality measure $\mathcal{N}(E_N)/\sqrt{N}$ (as $N \to \infty$) for random binary sequences $E_N$, by this means confirming a conjecture of Alon, Kohayakawa, Mauduit, Moreira and R{\"o}dl. ... More
Expanding and expansive time-dependent dynamicsOct 08 2014Jan 26 2015In this paper, time-dependent dynamical systems given by sequences of maps are studied. For systems built from expanding C^2-maps on a compact Riemannian manifold M with uniform bounds on expansion factors and derivatives, we provide formulas for the ... More
Quasi-homogeneity of the moduli space of stable maps to homogeneous spacesJun 20 2017Let $G$ be a connected, simply connected, simple, complex, linear algebraic group. Let $P$ be an arbitrary parabolic subgroup of $G$. Let $X=G/P$ be the $G$-homogeneous projective space attached to this situation. Let $d\in H_2(X)$ be a degree. Let $\overline{M}_{0,3}(X,d)$ ... More
Categorified central extensions, étale Lie 2-groups and Lie's Third Theorem for locally exponential Lie algebrasDec 09 2008Jul 01 2011Lie's Third Theorem, asserting that each finite-dimensional Lie algebra is the Lie algebra of a Lie group, fails in infinite dimensions. The modern account on this phenomenon is the integration problem for central extensions of infinite-dimensional Lie ... More
The two-dimensional density of Bernoulli ConvolutionsApr 01 2016Jul 22 2016Bernoulli convolutions form a one-parameter family of self-similar measures on the unit interval. We suggest to study their two-dimensional density which has an intricate combinatorial structure. Visualizing this structure we discuss results of Erd\"os, ... More
Public Spheres in Twitter- and Blogosphere. Evidence from the USAug 27 2014The political requires a forum for its deliberation and Habermas has located it in the public spheres. Originally, mass media's role was one of a facilitator of these debates. However, under the immense pressures of free market competition and mobile ... More
An Unified Definition of Data MiningSep 16 2008Since many years, theoretical concepts of Data Mining have been developed and improved. Data Mining has become applied to many academic and industrial situations, and recently, soundings of public opinion about privacy have been carried out. However, ... More
16 Propositions to Reconsider the Organization of a Scientific WorkshopSep 29 2008Participating a scientific workshop is nowadays often an adventure because the number of participants do seldom exceed the number of talks. A half-day workshop is mostly finished at lunchtime, speakers are sometimes not present and unexcused, and a strict ... More
Constrained Willmore Tori in the 4--SphereMar 05 2008We prove that a constrained Willmore immersion of a 2-torus into the conformal 4-sphere is either of "finite type", that is, has a spectral curve of finite genus, or is of "holomorphic type" which means that it is super conformal or Euclidean minimal ... More
Market-consistent valuation of insurance liabilities by cost of capitalDec 30 2010This paper investigates market-consistent valuation of insurance liabilities in the context of, for instance, Solvency II and to some extent IFRS 4. We propose an explicit and consistent framework for the valuation of insurance liabilities which incorporates ... More
Dark Matter Decay and Cosmic RaysOct 29 2009The decay of dark matter is predicted by many theoretical models and can produce observable contributions to the cosmic-ray fluxes. I shortly discuss the interpretation of the positron and electron excess as observed by PAMELA and Fermi LAT in terms of ... More
Aspects of Noncommutativity and Holography in Field Theory and String TheorySep 03 2004May 09 2005This thesis addresses two topics: noncommutative Yang-Mills theories and the AdS/CFT correspondence. In the first part we study a partial summation of the theta-expanded perturbation theory. The latter allows one to define noncommutative Yang-Mills theories ... More
Poincare Polynomials and Level Rank Dualities in the $N=2$ Coset ConstructionNov 29 1993We review the coset construction of conformal field theories; the emphasis is on the construction of the Hilbert spaces for these models, especially if fixed points occur. This is applied to the $N=2$ superconformal cosets constructed by Kazama and Suzuki. ... More
Information-theoretic considerations concerning the origin of lifeSep 02 2014Nov 22 2014Research investigating the origins of life usually focuses on exploring possible life-bearing chemistries in the pre-biotic Earth, or else on synthetic approaches. Little work has been done exploring fundamental issues concerning the spontaneous emergence ... More
Toward a fully relativistic theory of quantum informationDec 08 2011Information theory is a statistical theory dealing with the relative state of detectors and physical systems. Because of this physicality of information, the classical framework of Shannon needs to be extended to deal with quantum detectors, perhaps moving ... More
Rare D Meson Decays at HERASep 12 1996A status report on the prospects of measuring rare decays of charmed mesons at HERA is given. Based on actual experience with measuring charm at HERA, the sensitivity on limits of rare decays is estimated.
Spontaneous breaking of SU(3) to finite family symmetries: a pedestrian's approachJan 12 2011Non-Abelian discrete family symmetries play a pivotal role in the formulation of models with tri-bimaximal lepton mixing. We discuss how to obtain symmetries such as A4, semidirect product of Z7 and Z3, and Delta(27) from an underlying SU(3) gauge symmetry. ... More
Normalization of the chiral condensate in the massive Schwinger modelJun 25 1998Within mass perturbation theory, already the first order contribution to the chiral condensate of the massive Schwinger model is UV divergent. We discuss the problem of choosing a proper normalization and, by making use of some bosonization results, we ... More
Perturbative solution of the Schwinger modelJan 08 1996For the exactly solvable Schwinger model one interesting question is how to infer the exact solution from perturbation theory. We give a systematic procedure of deriving the exact solution from Feynman diagrams of arbitrary order for arbitrary $n$-point ... More