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Erdős-Szekeres and Testing Weak epsilon-Nets are NP-hard in 3 dimensions - and what now?Nov 25 2011We consider the computational versions of the Erd\H os-Szekeres theorem and related problems in 3 dimensions. We show that, in constrast to the planar case, no polynomial time algorithm exists for determining the largest (empty) convex subset (unless ... More

On the perturbation of positive semigroupsJul 17 2013We prove a perturbation result for positive semigroups, thereby extending a heat kernel estimate by Barlow, Grigor'yan and Kumagai for Dirichlet forms (\cite{bgk2009}) to positive semigroups. This also leads to a generalization of domination for semigroups ... More

Numerical integrators for motion under a strong constraining forceMar 17 2014Jul 22 2014This paper deals with the numerical integration of Hamiltonian systems in which a stiff anharmonic potential causes highly oscillatory solution behavior with solution-dependent frequencies. The impulse method, which uses micro- and macro-steps for the ... More

Base manifolds for Lagrangian fibrations on hyperkähler manifoldsMar 15 2013Jun 05 2013We show that the base manifold of a Lagrangian fibration on a hyperk\"ahler manifold is isomorphic to complex projective space. This generalises a theorem of J.-M. Hwang to the K\"ahler case.

Singular (Lipschitz) homology and homology of integral currentsFeb 23 2009We compare the homology groups $H_n ^{IC}(X)$ of the chain complex of integral currents with compact support of a metric space $X$ with the singular Lipschitz homology $H^L_n (X)$ and with ordinary singular homology. If $X$ satisfies certain cone inequalities ... More

Marginalization in nonlinear mixed-effects models with an application to dose-response analysisJul 08 2017Inference in hierarchical nonlinear models needs careful consideration about targeting parameters that have either a conditional or population-average interpretation. For the special case of mixed-effects nonlinear sigmoidal models we propose a method ... More

On Error Bounds and Multiplier Methods for Variational Problems in Banach SpacesJul 11 2018This paper deals with a general form of variational problems in Banach spaces which encompasses variational inequalities as well as minimization problems. We prove a characterization of local error bounds for the distance to the (primal-dual) solution ... More

Invariant meromorphic functions on Stein spacesOct 14 2010In this paper we develop fundamental tools and methods to study meromorphic functions in an equivariant setup. As our main result we construct quotients of Rosenlicht-type for Stein spaces acted upon holomorphically by complex-reductive Lie groups and ... More

Line defects in Graphene: How doping affects the electronic and mechanical propertiesJan 25 2016Graphene and carbon nanotubes have extraordinary mechanical and electronic properties. Intrinsic line defects such as local non-hexagonal reconstructions or grain boundaries, however, significantly reduce the tensile strength, but feature exciting electronic ... More

Augmented Lagrangian Methods for the Solution of Generalized Nash Equilibrium ProblemsJul 12 2018We propose an augmented Lagrangian-type algorithm for the solution of generalized Nash equilibrium problems (GNEPs). Specifically, we discuss the convergence properties with regard to both feasibility and optimality of limit points. This is done by introducing ... More

Quasi-Variational Inequalities in Banach Spaces: Theory and Augmented Lagrangian MethodsSep 30 2018Dec 03 2018This paper deals with quasi-variational inequality problems (QVIs) in a generic Banach space setting. We provide a theoretical framework for the analysis of such problems which is based on two key properties: the pseudomonotonicity (in the sense of Brezis) ... More

The Falicov-Kimball modelFeb 17 2005Aug 12 2005This is a review for Elsevier's Encyclopedia of mathematical physics.

Hamiltonian actions of unipotent groups on compact Kähler manifoldsMay 07 2018Nov 08 2018We study meromorphic actions of unipotent complex Lie groups on compact K\"ahler manifolds using moment map techniques. We introduce natural stability conditions and show that sets of semistable points are Zariski-open and admit geometric quotients that ... More

Electromagnetic Potential in Pre-Metric Electrodynamics: Causal Structure, Propagators and QuantizationFeb 02 2016Aug 03 2016An axiomatic approach to electrodynamics reveals that Maxwell electrodynamics is just one instance of a variety of theories for which the name electrodynamics is justified. They all have in common that their fundamental input are Maxwell's equations $\textrm{d} ... More

Some determinants of path generating functions, IIFeb 16 2018Aug 28 2018We evaluate Hankel determinants of matrices in which the entries are generating functions for paths consisting of up-steps, down-steps and level steps with a fixed starting point but variable end point. By specialisation, these determinant evaluations ... More

Computational Analysis of Composition-Structure-Property-Relationships in NZP-type Materials for Li-Ion BatteriesJan 28 2019Compounds crystallizing in the structure of NaZr$_2$(PO$_4$)$_3$ (NZP) are considered as promising materials for solid state electrolytes in Li-ion batteries. Using density functional theory (DFT), a systematic computational screening of 18 NZP compounds, ... More

An Augmented Lagrangian Method for Optimization Problems in Banach SpacesJul 12 2018We propose a variant of the classical augmented Lagrangian method for constrained optimization problems in Banach spaces. Our theoretical framework does not require any convexity or second-order assumptions and allows the treatment of inequality constraints ... More

Infrared Behaviour and Running Couplings in Interpolating Gauges in QCDApr 26 2005Aug 22 2005We consider the class of gauges that interpolates between Landau- and Coulomb-gauge QCD, and show the non-renormalisation of the two independent ghost-gluon vertices. This implies the existence of two RG-invariant running couplings, one of which is interpreted ... More

Fixed Parameter Complexity and Approximability of Norm MaximizationJul 24 2013The problem of maximizing the $p$-th power of a $p$-norm over a halfspace-presented polytope in $\R^d$ is a convex maximization problem which plays a fundamental role in computational convexity. It has been shown in 1986 that this problem is $\NP$-hard ... More

Control of open quantum systems: Case study of the central spin modelNov 30 2013We study the controllability of a central spin guided by a classical field and interacting with a spin bath, showing that the central spin is fully controllable independently of the number of bath spins. Additionally we find that for unequal system-bath ... More

Stock prices, inflation and inflation uncertainty in the U.S.: Testing the long-run relationship considering Dow Jones sector indexesMar 03 2016We test for the long-run relationship between stock prices, inflation and its uncertainty for different U.S. sector stock indexes, over the period 2002M7 to 2015M10. For this purpose we use a cointegration analysis with one structural break to capture ... More

Mechanisms for p-type behavior of ZnO, Zn$_{1-x}$Mg$_x$O and related oxide semiconductorsFeb 24 2016Possibilities of turning intrinsically n-type oxide semiconductors like ZnO and Zn$_{1-x}$Mg$_x$O into p-type materials are investigated. Motivated by recent experiments on Zn$_{1-x}$Mg$_x$O doped with nitrogen we analyze the electronic defect levels ... More

Model sets with positive entropy in Euclidean cut and project schemesMay 04 2016We construct model sets arising from cut and project schemes in Euclidean spaces whose associated Delone dynamical systems have positive toplogical entropy. The construction works both with windows that are proper and with windows that have empty interior. ... More

Comment on new physics contributions to Gamma_{12}^sJun 08 2010Jun 29 2010A recent measurement by the D0 collaboration finds a like-sign di-muon charge asymmetry in the B system that is roughly 3 sigma larger than the value predicated by the Standard Model. This suggests new physics contributing to B-Bbar mixing. For the current ... More

Hamiltonian and primary constraints of new general relativityNov 27 2018We derive the kinematic Hamiltonian for the so called "new general relativity" class of teleparallel gravity theories, which is the most general non-parity violating class of theories whose Lagrangian is quadratic in the torsion tensor. Our approach makes ... More

Defect turbulence and generalized statistical mechanicsFeb 28 2003We present experimental evidence that the motion of point defects in thermal convection patterns in an inclined fluid layer is well-described by Tsallis statistics with an entropic index $q \approx 1.5$. The dynamical properties of the defects (anomalous ... More

Simulations of Bunch Merging in a Beta Beam Decay RingSep 08 2011To further study neutrino oscillation properties a Beta Beam facility has been proposed. Beta decaying ions with high kinetic energy are stored in a storage ring ("Decay Ring") with straight sections to create pure focused (anti) electron neutrino beams. ... More

The Price of Gold: Curiosity?May 02 2019Gold open access as characterised by the payment of an article processing charge (APC) has become one of the dominant models in open access publication. This paper examines an extreme hypothetical case in which the APC model is the only model and the ... More

Algorithmic counting of nonequivalent compact Huffman codesJan 31 2019It is known that the following five counting problems lead to the same integer sequence~$f_t(n)$: the number of nonequivalent compact Huffman codes of length~$n$ over an alphabet of $t$ letters, the number of `nonequivalent' canonical rooted $t$-ary trees ... More

On Mordell-Weil groups and congruences between derivatives of twisted Hasse-Weil L-functionsMay 18 2015Let A be an abelian variety defined over a number field k and let F be a finite Galois extension of k. Let p be a prime number. Then under certain not-too-stringent conditions on A and F we compute explicitly the algebraic part of the p-component of the ... More

Robust classification of salient links in complex networksOct 18 2011May 31 2012Complex networks in natural, social, and technological systems generically exhibit an abundance of rich information. Extracting meaningful structural features from data is one of the most challenging tasks in network theory. Many methods and concepts ... More

The Standard Model Higgs as the origin of the hot Big BangApr 13 2016Jun 29 2017If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation - via non-perturbative effects - ... More

Megahertz Schlieren Imaging of Shock Structure and Sound Waves in Under-Expanded, Impinging JetsOct 15 2010The accompanying fluid dynamics videos visualize the temporal evolution of shock structures and sound waves in and around an under-expanded jet that is impinging on a rigid surface at varying pressure ratios. The recordings were obtained at frame rates ... More

A continuous-time diffusion limit theorem for dynamical decoupling and intrinsic decoherenceMay 29 2014Apr 13 2015We discuss a few mathematical aspects of random dynamical decoupling, a key tool procedure in quantum information theory. In particular, we place it in the context of discrete stochastic processes, limit theorems and CPT semigroups on matrix algebras. ... More

The MSW Effect in Quantum Field TheoryApr 12 1999We show in detail the general relationship between the Schr\"{o}dinger equation approach to calculating the MSW effect and the quantum field theoretical S-matrix approach. We show the precise form a generic neutrino propagator must have to allow a physically ... More

Quantum Energy Inequalities in Pre-Metric ElectrodynamicsSep 06 2017Oct 04 2017Pre-metric electrodynamics is a covariant framework for electromagnetism with a general constitutive law. Its lightcone structure can be more complicated than that of Maxwell theory as is shown by the phenomenon of birefringence. We study the energy density ... More

Lagrangian fibrations on hyperkähler manifolds - On a question of BeauvilleMay 17 2011Nov 08 2012Let X be a compact hyperk\"ahler manifold containing a complex torus L as a Lagrangian subvariety. Beauville posed the question whether X admits a Lagrangian fibration with fibre L. We show that this is indeed the case if X is not projective. If X is ... More

Agent-Based Simulation Modelling for Reflecting on Consequences of Digital Mental HealthFeb 05 2019The premise of this working paper is based around agent-based simulation models and how to go about creating them from given incomplete information. Agent-based simulations are stochastic simulations that revolve around groups of agents that each have ... More

Functional error estimators for the adaptive discretization of inverse problemsJul 29 2015Aug 31 2016So-called functional error estimators provide a valuable tool for reliably estimating the discretization error for a sum of two convex functions. We apply this concept to Tikhonov regularization for the solution of inverse problems for partial differential ... More

An Interpolation Procedure for List Decoding Reed--Solomon codes Based on Generalized Key EquationsOct 18 2011The key step of syndrome-based decoding of Reed-Solomon codes up to half the minimum distance is to solve the so-called Key Equation. List decoding algorithms, capable of decoding beyond half the minimum distance, are based on interpolation and factorization ... More

Evolution of holographic entanglement entropy in an anisotropic systemJun 08 2015Jun 19 2015We determine holographically 2-point correlators of gauge invariant operators with large conformal weights and entanglement entropy of strips for a time-dependent anisotropic 5-dimensional asymptotically anti-de Sitter spacetime. At the early stage of ... More

Critical Transitions in Social Network ActivityJul 31 2013Nov 13 2013A large variety of complex systems in ecology, climate science, biomedicine and engineering have been observed to exhibit tipping points, where the internal dynamical state of the system abruptly changes. For example, such critical transitions may result ... More

On the Galois structure of Selmer groupsMay 18 2015Let A be an abelian variety defined over a number field k and F a finite Galois extension of k. Let p be a prime number. Then under certain not-too-stringent conditions on A and F we investigate the explicit Galois structure of the p-primary Selmer group ... More

Dynamical Decoupling and Homogenization of continuous variable systemsMay 19 2016For finite-dimensional quantum systems, such as qubits, a well established strategy to protect such systems from decoherence is dynamical decoupling. However many promising quantum devices, such as oscillators, are infinite dimensional, for which the ... More

The Standard Model Higgs as the origin of the hot Big BangApr 13 2016If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation -- via non-perturbative effects -- ... More

Generalized Berezin quantization, Bergman metrics and fuzzy LaplaciansApr 29 2008Sep 09 2008We study extended Berezin and Berezin-Toeplitz quantization for compact Kaehler manifolds, two related quantization procedures which provide a general framework for approaching the construction of fuzzy compact Kaehler geometries. Using this framework, ... More

Functional error estimators for the adaptive discretization of inverse problemsJul 29 2015Feb 10 2017So-called functional error estimators provide a valuable tool for reliably estimating the discretization error for a sum of two convex functions. We apply this concept to Tikhonov regularization for the solution of inverse problems for partial differential ... More

On compositions with $x^2/(1-x)$Apr 03 2014In the past, empirical evidence has been presented that Hilbert series of symplectic quotients of unitary representations obey a certain universal system of infinitely many constraints. Formal series with this property have been called \emph{symplectic}. ... More

Uniformity of hitting times of the contact processApr 29 2017For the supercritical contact process on the hyper-cubic lattice started from a single infection at the origin and conditioned on survival, we establish two uniformity results for the hitting times $t(x)$, defined for each site $x$ as the first time at ... More

Using clustering of rankings to explain brand preferences with personality and socio-demographic variablesApr 04 2017The primary aim of market segmentation is to identify relevant groups of consumers that can be addressed efficiently by marketing or advertising campaigns. This paper addresses the issue whether consumer groups can be identified from background variables ... More

The Laurent coefficients of the Hilbert series of a Gorenstein algebraMay 05 2016Nov 01 2017By a theorem of R. Stanley, a graded Cohen-Macaulay domain $A$ is Gorenstein if and only if its Hilbert series satisfies the functional equation \[ \operatorname{Hilb}_A(t^{-1})=(-1)^d t^{-a}\operatorname{Hilb}_A(t), \] where $d$ is the Krull dimension ... More

On the gauge fixing in the Hamiltonian analysis of general teleparallel theoriesMay 03 2019The covariant formulation of teleparallel gravity theories must include the spin connection, which has 6 degrees of freedom. One can, however, always choose a gauge such that the spin connection is put to zero. In principle this gauge may affect counting ... More

Lagrangian fibrations on hyperkähler fourfoldsOct 12 2011Nov 07 2012Let X be a projective hyperk\"ahler manifold containing a Lagrangian subtorus L. We study intersections of deformations of L, defining a canonical almost holomorphic map called L-reduction, which is not birational if and only if X admits an almost holomorphic ... More

Magnetoconductance switching in an array of oval quantum dotsApr 24 2009Employing oval shaped quantum billiards connected by quantum wires as the building blocks of a linear quantum dot array, we calculate the ballistic magnetoconductance in the linear response regime. Optimizing the geometry of the billiards, we aim at a ... More

An algebra generated by $x - 2$May 05 2016Jun 13 2016By a theorem of R. Stanley, a graded Cohen-Macaulay domain $A$ is Gorenstein if and only if its Hilbert series satisfies the functional equation \[ \operatorname{Hilb}_A(t^{-1})=(-1)^d t^{-a}\operatorname{Hilb}_A(t), \] where $d$ is the Krull dimension ... More

Dynamical Decoupling and Homogenization of continuous variable systemsMay 19 2016Mar 08 2017For finite-dimensional quantum systems, such as qubits, a well established strategy to protect such systems from decoherence is dynamical decoupling. However many promising quantum devices, such as oscillators, are infinite dimensional, for which the ... More

Zero measure Cantor spectra for continuum one-dimensional quasicrystalsAug 15 2013We study Schr\"odinger operators on $\R$ with measures as potentials. Choosing a suitable subset of measures we can work with a dynamical system consisting of measures. We then relate properties of this dynamical system with spectral properties of the ... More

Hamiltonian and primary constraints of new general relativityNov 27 2018May 03 2019We derive the kinematic Hamiltonian for the so-called "new general relativity" class of teleparallel gravity theories, which is the most general class of theories whose Lagrangian is quadratic in the torsion tensor and does not contain parity violating ... More

Fourth generation quark mass limits in CKM-element spaceJan 25 2011We present a reanalysis of CDF data to extend limits on individual fourth-generation quark masses from particular flavor-mixing rates to the entire space of possible mixing values. Measurements from CDF have set individual limits on masses, $m_{b'}$ and ... More

Magnetic field-induced control of transport in multiterminal focusing quantum billiardsDec 19 2010Mar 02 2011By exploring the four-terminal transmission of a semi-elliptic open quantum billiard in dependence of its geometry and an applied magnetic field, it is shown that a controllable switching of currents between the four terminals can be obtained. Depending ... More

Singleton physicsJan 12 1999We review the developments in the past twenty years (which are based on our deformation philosophy of physical theories) dealing with elementary particles composed of singletons in anti De Sitter space-time. The study starts with the kinematical aspects ... More

Generalized Berezin-Toeplitz quantization of Kaehler supermanifoldsNov 28 2008May 15 2009We extend the construction of generalized Berezin and Berezin-Toeplitz quantization to the case of compact Hodge supermanifolds. Our approach is based on certain super-analogues of Rawnsley's coherent states. As applications, we discuss the quantization ... More

Hilbert series associated to symplectic quotients by $\operatorname{SU}_2$Sep 20 2018We compute the Hilbert series of the graded algebra of real regular functions on the symplectic quotient associated to an $\operatorname{SU}_2$-module and give an explicit expression for the first nonzero coefficient of the Laurent expansion of the Hilbert ... More

Relaxation schemes for mathematical programs with switching constraintsSep 07 2018Switching-constrained optimization problems form a difficult class of mathematical programs since their feasible set is almost disconnected while standard constraint qualifications are likely to fail at several feasible points. That is why the application ... More

Model sets with positive entropy in Euclidean cut and project schemesMay 04 2016Jun 25 2018We construct model sets arising from cut and project schemes in Euclidean spaces whose associated Delone dynamical systems have positive toplogical entropy. The construction works both with windows that are proper and with windows that have empty interior. ... More

The parameterized complexity of some geometric problems in unbounded dimensionJun 18 2009We study the parameterized complexity of the following fundamental geometric problems with respect to the dimension $d$: i) Given $n$ points in $\Rd$, compute their minimum enclosing cylinder. ii) Given two $n$-point sets in $\Rd$, decide whether they ... More

CO adsorption on neutral iridium clustersSep 27 2010The adsorption of carbon monoxide on neutral iridium clusters in the size range of n = 3 to 21 atoms is investigated with infrared multiple photon dissociation spectroscopy. For each cluster size only a single v(CO) band is present with frequencies in ... More

Systematic Physics Constrained Parameter Estimation of Stochastic Differential EquationsDec 06 2013Aug 11 2014A systematic Bayesian framework is developed for physics constrained parameter inference ofstochastic differential equations (SDE) from partial observations. The physical constraints arederived for stochastic climate models but are applicable for many ... More

3D Lyman-alpha radiation transfer. III. Constraints on gas and stellar properties of z~3 Lyman break galaxies (LBG) and implications for high-z LBGs and Lyman-alpha emitters(LAEs)May 23 2008The Aim of our study is to understand the variety of observed Lyman-alpha (Lya) line profiles and strengths in Lyman Break Galaxies (LBGs) and Lya emitters (LAEs), the physical parameters governing them, and hence deriving constraints on the gas and dust ... More

Analysis of Agglomerative ClusteringDec 16 2010Mar 07 2014The diameter $k$-clustering problem is the problem of partitioning a finite subset of $\mathbb{R}^d$ into $k$ subsets called clusters such that the maximum diameter of the clusters is minimized. One early clustering algorithm that computes a hierarchy ... More

B.A.T.Mobile: Leveraging Mobility Control Knowledge for Efficient Routing in Mobile Robotic NetworksJul 05 2016Efficient routing is one of the key challenges of wireless networking for unmanned autonomous vehicles (UAVs) due to dynamically changing channel and network topology characteristics. Various well known mobile-ad-hoc routing protocols, such as AODV, OLSR ... More

NLO results for five, six and seven jets in electron-positron annihilationNov 07 2011We present next-to-leading order corrections in the leading colour approximation for jet rates in electron-positron annihilation up to seven jets. The results for the two-, three-, and four-jet rates agree with known results. The NLO jet rates have been ... More

Competitive Routing in Hybrid Communication NetworksOct 25 2017Feb 28 2018Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing ... More

Lindbladian purificationJan 11 2017In a recent work [D. K. Burgarth et al., Nat. Commun. 5, 5173 (2014)] it was shown that a series of frequent measurements can project the dynamics of a quantum system onto a subspace in which the dynamics can be more complex. In this subspace even full ... More

Turbulent Drag Reduction of polyelectrolyte (DNA) solutions: relation with the elongational viscosityOct 24 2001Jul 23 2003We report measurements of turbulent drag reduction of two different polyelectrolyte solutions: DNA and hydrolyzed Polyacrylamide. Changing the salt concentration in the solutions allows us to change the flexibility of the polymer chains. For both polymers ... More

Proton Cyclotron Waves Upstream from Mars: Observations from Mars Global SurveyorFeb 14 2013We present a study on the properties of electromagnetic plasma waves in the region upstream of the Martian bow shock, detected by the magnetometer and electron reflectometer (MAG / ER) onboard the Mars Global Surveyor (MGS) spacecraft during the period ... More

Experimental Schmidt Decomposition and Entanglement DetectionNov 15 2011Jun 20 2012We introduce an experimental procedure for the detection of quantum entanglement of an unknown quantum state with as few measurements as possible. The method requires neither a priori knowledge of the state nor a shared reference frame between the observers. ... More

The roles of drift and control field constraints upon quantum control speed limitsApr 20 2017Oct 23 2017In this work we derive a lower bound for the minimum time required to implement a target unitary transformation through a classical time-dependent field in a closed quantum system. The bound depends on the target gate, the strength of the internal Hamiltonian ... More

Computational efficiency of staggered Wilson fermions: A first lookDec 11 2013Dec 17 2013Results on the computational efficiency of 2-flavor staggered Wilson fermions compared to usual Wilson fermions in a quenched lattice QCD simulation on $16^3\times32$ lattice at $\beta=6$ are reported. We compare the cost of inverting the Dirac matrix ... More

Learning Structural Kernels for Natural Language ProcessingAug 10 2015Structural kernels are a flexible learning paradigm that has been widely used in Natural Language Processing. However, the problem of model selection in kernel-based methods is usually overlooked. Previous approaches mostly rely on setting default values ... More

A convergent time-space adaptive dG(s) finite element method for parabolic problems motivated by equal error distributionOct 21 2016We shall develop a fully discrete space-time adaptive method for linear parabolic problems based on new reliable and efficient a posteriori analysis for higher order dG(s) finite element discretisations. The adaptive strategy is motivated by the principle ... More

On Evaluating Embedding Models for Knowledge Base CompletionOct 17 2018Jan 31 2019Knowledge bases contribute to many web search and mining tasks, yet they are often incomplete. To add missing facts to a given knowledge base, various embedding models have been proposed in the recent literature. Perhaps surprisingly, relatively simple ... More

Trajectory-Based Off-Policy Deep Reinforcement LearningMay 14 2019Policy gradient methods are powerful reinforcement learning algorithms and have been demonstrated to solve many complex tasks. However, these methods are also data-inefficient, afflicted with high variance gradient estimates, and frequently get stuck ... More

A disk-covering problem with application in optical interferometryDec 05 2006Given a disk O in the plane called the objective, we want to find n small disks P_1,...,P_n called the pupils such that $\bigcup_{i,j=1}^n P_i \ominus P_j \supseteq O$, where $\ominus$ denotes the Minkowski difference operator, while minimizing the number ... More

Coarse-Graining Can Beat the Rotating Wave Approximation in Quantum Markovian Master EquationsMar 26 2013We present a first-principles derivation of the Markovian semi-group master equation without invoking the rotating wave approximation (RWA). Instead we use a time coarse-graining approach which leaves us with a free timescale parameter, which we can optimize. ... More

Joint Design of Channel and Network Coding for Star NetworksJan 28 2013Channel coding alone is not sufficient to reliably transmit a message of finite length $K$ from a source to one or more destinations as in, e.g., file transfer. To ensure that no data is lost, it must be combined with rateless erasure correcting schemes ... More

A new algorithm for point spread function subtraction in high-contrast imaging: a demonstration with angular differential imagingFeb 26 2007Direct imaging of exoplanets is limited by bright quasi-static speckles in the point spread function (PSF) of the central star. This limitation can be reduced by subtraction of reference PSF images. We have developed an algorithm to construct an optimized ... More

The Cremmer-Scherk Mechanism in F-theory Compactifications on K3 ManifoldsMar 06 2014Oct 21 2016It is well understood --- through string dualities --- that there are 20 massless vector fields in the spectrum of eight-dimensional F-theory compactifications on smooth elliptically fibered K3 surfaces at a generic point in the K3 moduli space. Such ... More

Dynamical Decoupling of Unbounded HamiltoniansApr 20 2017We investigate the possibility to suppress interactions between a finite dimensional system and an infinite dimensional environment through a fast sequence of unitary kicks on the finite dimensional system. This method, called dynamical decoupling, is ... More

Sparse Models and Methods for Optimal Instruments with an Application to Eminent DomainOct 21 2010Apr 19 2015We develop results for the use of Lasso and Post-Lasso methods to form first-stage predictions and estimate optimal instruments in linear instrumental variables (IV) models with many instruments, $p$. Our results apply even when $p$ is much larger than ... More

Bayesian identification of sound sources with the Helmholtz equationMay 29 2018Jan 15 2019In this work we discuss the problem of identifying sound sources from pressure measurements with a Bayesian approach. The acoustics are modelled by the Helmholtz equation and the goal is to get information about the number, strength and position of the ... More

Efficient Error-Correcting GeocodingFeb 16 2011We study the problem of resolving a perhaps misspelled address of a location into geographic coordinates of latitude and longitude. Our data structure solves this problem within a few milliseconds even for misspelled and fragmentary queries. Compared ... More

Byzantine Fault Tolerant Vector Consensus with Anonymous ProposalsFeb 26 2019In this paper, we introduce the anonymous proposer vector consensus problem in which a set of processes decide on a vector of values, where each value is a proposal made anonymously by a single process. In a distributed survey, for example, a solution ... More

ADS as Information Management Service in an M-Learning EnvironmentAug 04 2007Leveraging the potential power of even small handheld devices able to communicate wirelessly requires dedicated support. In particular, collaborative applications need sophisticated assistance in terms of querying and exchanging different kinds of data. ... More

Hardness of discrepancy computation and epsilon-net verification in high dimensionMar 23 2011Discrepancy measures how uniformly distributed a point set is with respect to a given set of ranges. There are two notions of discrepancy, namely continuous discrepancy and combinatorial discrepancy. Depending on the ranges, several possible variants ... More

Continuous-time limit of topological quantum walksNov 22 2016We derive the continuous-time limit of discrete quantum walks with topological phases. We show the existence of a continuous-time limit that preserves their topological phases. We consider both simple-step and split-step walks, and derive analytically ... More

Maps of sparse Markov chains efficiently reveal community structure in network flows with memoryJun 27 2016To better understand the flows of ideas or information through social and biological systems, researchers develop maps that reveal important patterns in network flows. In practice, network flow models have implied memoryless first-order Markov chains, ... More

Instrumenting an SMT Solver to Solve Hybrid Network Reachability ProblemsSep 13 2016PDDL+ planning has its semantics rooted in hybrid automata (HA) and recent work has shown that it can be modeled as a network of HAs. Addressing the complexity of nonlinear PDDL+ planning as HAs requires both space and time efficient reasoning. Unfortunately, ... More

Glassy states: the free Ising model on a treeSep 02 2017Oct 22 2018We consider the ferromagnetic Ising model on the Cayley tree and we investigate the decomposition of the free state into extremal states below the spin glass temperature. We show that this decomposition has uncountably many components. The tail observable ... More

The A-theoretic Farrell-Jones Conjecture for virtually solvable groupsSep 23 2016Oct 11 2016We prove the A-theoretic Farrell-Jones Conjecture for virtually solvable groups. As a corollary, we obtain that the conjecture holds for S-arithmetic groups and lattices in almost connected Lie groups.