Results for "Gerd Steinle-Neumann"

total 1508took 0.13s
Evidence of local magnetic order in hcp iron from Raman mode splittingNov 26 2001Experimental measurements of Raman spectra for hcp iron at high pressure show two modes over a considerable pressure range in contrast to the prediction of one doubly degenerate mode for the hcp lattice. We use density functional theory to investigate ... More
Comment on "On the importance of the free energy for elasticity under pressure"Apr 14 2004Marcus et al. (Marcus P, Ma H and Qiu S L 2002 J. Phys.: Condens. Matter 14 L525) claim that thermodynamic properties of materials under pressure must be computed using the Gibbs free energy $G$, rather than the internal energy $E$. Marcus et al. state ... More
Saturation and negative temperature coefficient of electrical resistivity in liquid iron-sulfur alloys at high densities from first principles calculationsMar 07 2018We report results on electronic transport properties of liquid Fe-S alloys at conditions of planetary cores, computed by first-principle techniques in the Kubo-Greenwood formalism. We describe a combined effect of resistivity saturation due to temperature, ... More
Physical Properties of Iron in the Inner CoreApr 18 2002The Earth's inner core plays a vital role in the dynamics of our planet and is itself strongly exposed to dynamic processes as evidenced by a complex pattern of elastic structure. To gain deeper insight into the nature of these processes we rely on a ... More
Absence of lattice strain anomalies at the electronic topological transition in zinc at high pressureMay 30 2000Oct 16 2000High pressure structural distortions of the hexagonal close packed (hcp) element zinc have been a subject of controversy. Earlier experimental results and theory showed a large anomaly in lattice strain with compression in zinc at about 10 GPa which was ... More
Spontaneous charge carrier localization in extended one-dimensional systemsSep 17 2015Jan 12 2016Charge carrier localization in extended atomic systems has been described previously as being driven by disorder, point defects or distortions of the ionic lattice. Here we show for the first time by means of first-principles computations that charge ... More
Deviations from piecewise linearity in the solid-state limit with approximate density functionalsSep 16 2014In exact density functional theory (DFT) the total ground-state energy is a series of linear segments between integer electron points, a condition known as "piecewise linearity". Deviation from this condition is indicative of poor predictive capabilities ... More
A new ab initio equation of state of hcp-Fe and its implication on the interior structure and mass-radius relations of rocky super-EarthsMay 26 2018More than a third of all exoplanets can be classified as super-Earths based on radius (1-2 $R_{\bigoplus}$) and mass (< 10 $M_{\bigoplus}$). Here we model mass-radius relations based on silicate mantle and iron core equations of state to infer to first ... More
Pressure induced Hydrogen-Hydrogen interaction in metallic FeH revealed by NMRFeb 08 2019Knowledge of the behavior of hydrogen in metal hydrides is the key for understanding their electronic properties. So far, no experimental methods exist to access these properties beyond 100 GPa, where high-Tc superconductivity emerges. Here, we present ... More
Valence of complex-valued planar harmonic functionsJan 26 2004The valence of a function $f$ at a point $w$ is the number of distinct, finite solutions to $f(z) = w$. Let $f$ be a complex-valued harmonic function in an open set $R \subseteq \mathbb{C}$. Let $S$ denote the critical set of $f$ and $C(f)$ the global ... More
Applying Explanation-based Learning to Control and Speeding-up Natural Language GenerationDec 08 1997This paper presents a method for the automatic extraction of subgrammars to control and speeding-up natural language generation NLG. The method is based on explanation-based learning (EBL). The main advantage for the proposed new method for NLG is that ... More
Computational Complexity Analysis of Multi-Objective Genetic ProgrammingMar 22 2012The computational complexity analysis of genetic programming (GP) has been started recently by analyzing simple (1+1) GP algorithms for the problems ORDER and MAJORITY. In this paper, we study how taking the complexity as an additional criteria influences ... More
Importance of Magnetism in Phase Stability, Equations of State, and ElasticityOct 01 2001Jul 24 2002The effects of magnetism on high pressure properties of transition metals and transition metal compounds can be quite important. In the case of Fe, magnetism is responsible for stability of the body-centered cubic (bcc) phase at ambient conditions, and ... More
First-Principles Elastic Constants for the hcp Transition Metals Fe, Co, and Re at High PressureApr 29 1999The elastic constant tensors for the hcp phases of three transition metals (Co, Re, and Fe) are computed as functions of pressure using the Linearized Augmented Plane Wave method with both the local density and generalized gradient approximations. Spin-polarized ... More
Regularity in $L_p$ Sobolev spaces of solutions to fractional heat equationsJun 19 2017Jan 01 2018This work contributes in two areas, with sharp results, to the current investigation of regularity of solutions of heat equations (*) $Pu+\partial_tu=f$ on $\Omega\times I $, where $P$ is a nonlocal operator, and $\Omega \subset R^n$, $I\subset R$. 1) ... More
Optimal Control of Quasistatic Plasticity with Linear Kinematic Hardening Part I: Existence and Discretization in TimeSep 05 2012In this paper we consider an optimal control problem governed by a time-dependent variational inequality arising in quasistatic plasticity with linear kinematic hardening. We address certain continuity properties of the forward operator, which imply the ... More
Limited regularity of solutions to fractional heat and Schrödinger equationsJun 26 2018Dec 17 2018When $P$ is the fractional Laplacian $(-\Delta )^a$, $0<a<1$, or a pseudodifferential generalization thereof, the Dirichlet problem for the associated heat equation over a smooth set $\Omega \subset{\Bbb R}^n$: $r^+Pu(x,t)+\partial_tu(x,t)=f(x,t)$ on ... More
Extension theory for elliptic partial differential operators with pseudodifferential methodsAug 05 2010Sep 15 2011This is a short survey on the connection between general extension theories and the study of realizations of elliptic operators A on smooth domains in R^n, n > 1. The theory of pseudodifferential boundary problems has turned out to be very useful here, ... More
The mixed boundary value problem, Krein resolvent formulas and spectral asymptotic estimatesApr 05 2011Apr 28 2011For a second-order symmetric strongly elliptic operator A on a smooth bounded open set \Omega in R^n with boundary \Sigma, the mixed problem is defined by a Neumann-type condition on a part Sigma_+ of the boundary and a Dirichlet condition on the other ... More
Spectral boundary conditions for generalizations of Laplace and Dirac operatorsFeb 24 2003Apr 04 2003Spectral boundary conditions for Laplace-type operators, of interest in string and brane theory, are partly Dirichlet, partly Neumann-type conditions, partitioned by a pseudodifferential projection. We give sufficient conditions for existence of associated ... More
Dynamical Correspondence in a Generalized Quantum TheoryFeb 02 2014Mar 06 2015In order to figure out why quantum physics needs the complex Hilbert space, many attempts have been made to distinguish the C*-algebras and von Neumann algebras in more general classes of abstractly defined Jordan algebras (JB- and JBW-algebras). One ... More
Third-order interference and a principle of `quantumness'Mar 03 2011Are there physical, probabilistic or information-theoretic principles which characterize the quantum probabilities and distinguish them from the classical case as well as from other probability theories, or which reveal why quantum mechanics requires ... More
A Representation of Quantum Measurement in Nonassociative AlgebrasFeb 03 2010Starting from an abstract setting for the Lueders - von Neumann quantum measurement process and its interpretation as a probability conditionalization rule in a non-Boolean event structure, the author derived a certain generalization of operator algebras ... More
Non-Boolean probabilities and quantum measurementJan 21 2010A non-Boolean extension of the classical probability model is proposed. The non-Boolean probabilities reproduce typical quantum phenomena. The proposed model is more general and more abstract, but easier to interpret, than the quantum mechanical Hilbert ... More
The irreducible components of Hilb^{4n}(P^3)Nov 19 2008It is shown that Hilb^{4n}(P^3)has exactly two irreducible components.
Quantitative Calculation of the Spatial Extension of the Kondo CloudOct 26 2007The internal s-electron polarization in the ground state of a Friedel-Anderson and a Kondo impurity is calculated. The Wilson basis with exponentially fine energies close to the Fermi level is used and expressed in terms of free electron waves with linear ... More
The Conductance of a Perfect Thin Film with Diffuse Surface ScatteringFeb 20 2005The conductance of thin films with diffusive surface scattering was solved semi-classically by Fuchs and Sondheimer. However, when the intrinsic electron mean free path is very large or infinite their conductance diverges. In this letter a simple diffraction ... More
Analysis of Invariants Associated with Spectral Boundary Problems for an Elliptic OperatorJun 08 2004This is a survey of recent results on zeta- and eta-function poles and values for realizations of Laplace- and Dirac-type operators defined by pseudodifferential projection boundary conditions (including the Atiyah-Patodi-Singer operator and its square). ... More
Electron-Phonon Mass Enhancement in Multi-LayersOct 07 2006A strong electron-phonon interaction in a metal increases the electron density of states in the vicinity of the Fermi energy dramatically. This phenomenon is called electron-phonon mass enhancement. In this paper the question is investigated whether the ... More
Neutrinos from SN 1987a. A Puzzle RevisitedJul 25 2015The smallest of the four detectors which claim to have observed neutrinos from SN 1987a registered the events more than 4 h earlier than the other three ones. This claim is not usually accepted because it is difficult to understand that the other (and ... More
Non-classical conditional probability and the quantum no-cloning theoremFeb 07 2015Aug 13 2015The quantum mechanical no-cloning theorem for pure states is generalized and transfered to the quantum logics with a conditional probability calculus in a rather abstract, though simple and basic fashion without relying on a tensor product construction ... More
An Empirical Study of the Effect of Granting Multiple Tries for Online HomeworkJul 08 2014When deploying online homework in physics courses, an important consideration is how many attempts should be allowed in order to solve numerical free-response problems. While on the one hand, the maximum number of attempts should be large enough to allow ... More
Integration by parts and Pohozaev identities for space-dependent fractional-order operatorsNov 12 2015Apr 18 2016Consider a classical elliptic pseudodifferential operator $P$ on ${\Bbb R}^n$ of order $2a$ ($0<a<1)$ with even symbol. For example, $P=A(x,D)^a$ where $A(x,D)$ is a second-order strongly elliptic differential operator; the fractional Laplacian $(-\Delta ... More
A resolvent approach to traces and zeta Laurent expansionsNov 06 2003Dec 19 2005Classical pseudodifferential operators A on closed manifolds are considered. It is shown that the basic properties of the canonical trace TR A introduced by Kontsevich and Vishik are easily proved by identifying it with the leading nonlocal coefficient ... More
Green's formula for the fractional Laplacian and perturbationsApr 07 2019Let $\Omega $ be an open, smooth, bounded subset of $ \Bbb R ^n$. In connection with the fractional Laplacian $(-\Delta )^a$ ($a>0$), and more generally for a $2a$-order classical pseudodifferential operator ($\psi $do) $P$ with even symbol, one can define ... More
Green's formula and a Dirichlet-to-Neumann operator for fractional-order pseudodifferential operatorsNov 09 2016The paper treats boundary value problems for the fractional Laplacian $(-\Delta )^a$, $a>0$, and its generalizations to pseudodifferential operators ($\psi $do's) $P$ of order $2a$ with even symbol, applied to functions on a smooth subset $\Omega $ of ... More
Friedel oscillations of Kondo impurities: A comparisonMay 06 2008Recently Affleck et al. derived the existence of Friedel oscillations in the presence of a Kondo impurity. They supported their analytic derivation by numerical calculations using Wilson's renormalization approach (NRG). In this paper the size of the ... More
On the logarithm component in trace defect formulasNov 22 2004In asymptotic expansions of resolvent traces $\Tr(A(P-\lambda)^{-1})$ for classical pseudodifferential operators on closed manifolds, the coefficient $C_0(A,P)$ of $(-\lambda)^{-1}$ is of special interest, since it is the first coefficient containing ... More
Characteristic classes in $TMF$ of level $Γ_1(3)$Apr 12 2013Sep 30 2014Let $TMF_1(n)$ be the spectrum of topological modular forms equipped with a $\Gamma_1(n)$-structure. We compute the $K(2)$-local $TMF_1(3)$-cohomology of $B{\mathit String}$ and $B{\mathit Spin}$: both are power series rings freely generated by classes ... More
The Heart of FidelityJul 10 2012The multi-electron wave function of an interacting electron system depends on the size of the system, i.e. the number of electrons. Here the question investigated is how the wave function changes for a symmetric Friedel-Anderson impurity when the volume ... More
No-gap second-order conditions under $n$-polyhedric constraints and finitely many nonlinear constraintsFeb 20 2019We consider an optimization problem subject to an abstract constraint and finitely many nonlinear constraints. Using the recently introduced concept of $n$-polyhedricity, we are able to provide second-order optimality conditions under weak regularity ... More
Pauli Blocking in Degenerate Plasmas and the Separable Potential ApproachJan 23 2019The Mott effect describes the dissolution of bound states in a dense partially ionized plasma. It happens when the ionization potential depression, owing to effects of correlation and degeneracy, compensates the binding energy of the bound state. At high ... More
A note on the realization of relative $h_\infty$-diagramsSep 26 2018Oct 23 2018We prove a relative version of the realization theorem for $h_\infty$-diagrams in case that the underlying diagram subcategory is factorization-closed.
Three-slit experiments and quantum nonlocalityApr 01 2011Apr 24 2013An interesting link between two very different physical aspects of quantum mechanics is revealed; these are the absence of third-order interference and Tsirelson's bound for the nonlocal correlations. Considering multiple-slit experiments - not only the ... More
Different Types of Conditional Expectation and the Lueders - von Neumann Quantum MeasurementJan 21 2010In operator algebra theory, a conditional expectation is usually assumed to be a projection map onto a sub-algebra. In the paper, a further type of conditional expectation and an extension of the Lueders - von Neumann measurement to observables with continuous ... More
Conditional probability, three-slit experiments, and the Jordan algebra structure of quantum mechanicsDec 01 2009Sep 30 2012Most quantum logics do not allow for a reasonable calculus of conditional probability. However, those ones which do so provide a very general and rich mathematical structure, including classical probabilities, quantum mechanics as well as Jordan algebras. ... More
How the Kondo ground state avoids the orthogonality catastropheNov 20 2008In the presence of a magnetic impurity the spin-up and down band states are modified differently by the impurity. If the multi-electron scalar product (MESP) between the occupied spin-up and down states approaches zero then this defines an orthogonality ... More
A Compact Approximate Solution to the Friedel-Anderson Impuriy ProblemFeb 08 2006An approximate groundstate of the Anderson-Friedel impurity problem is presented in a very compact form. It requires solely the optimization of two localized electron states and consists of four Slater states (Slater determinants). The resulting singlet ... More
A Critical Analysis of the Mean-Field Approximation for the Calculation of the Magnetic Moment in the Friedel-Anderson Impurity ModelAug 29 2005It is shown that the calculation of the magnetic moment of a Friedel-Anderson impurity in mean-field theory is unreliable. A class of approximate solutions, which contains the mean-field solution as an element, is expressed in rotated Hilbert space and ... More
Symmetries of Surface SingularitiesApr 24 1996The automorphism group ${\rm Aut}\: X$ of a weighted homogeneous normal surface singularity $X$ has a maximal reductive algebraic subgroup $G$ which contains every reductive algebraic subgroup of ${\rm Aut}\: X$ up to conjugation. In all cases except ... More
Quantum key distribution without the wavefunctionNov 08 2016A well-known feature of quantum mechanics is the secure exchange of secret bit strings which can then be used as keys to encrypt messages transmitted over any classical communication channel. It is demonstrated that this quantum key distribution allows ... More
Spectral asymptotics for nonsmooth singular Green operatorsMay 01 2012Jun 28 2013Singular Green operators G appear typically as boundary correction terms in resolvents for elliptic boundary value problems on a domain \Omega \subset R^n, and more generally they appear in the calculus of pseudodifferential boundary problems. In particular, ... More
Krein resolvent formulas for elliptic boundary problems in nonsmooth domainsOct 15 2008The paper reports on a recent construction of M-functions and Krein resolvent formulas for general closed extensions of an adjoint pair, and their implementation to boundary value problems for second-order strongly elliptic operators on smooth domains. ... More
Perturbation of essential spectra of exterior elliptic problemsNov 11 2008Nov 17 2009For a second-order strongly elliptic differential operator on an exterior domain in R^n it is known from works of Birman and Solomiak that a change of the boundary condition from the Dirichlet condition to an elliptic Neumann or Robin condition leaves ... More
Green's formula and a Dirichlet-to-Neumann operator for fractional-order pseudodifferential operatorsNov 09 2016Mar 01 2018The paper treats boundary value problems for the fractional Laplacian $(-\Delta )^a$, $a>0$, and more generally for classical pseudodifferential operators ($\psi $do's) $P$ of order $2a$ with even symbol, applied to functions on a smooth subset $\Omega ... More
Remarks on nonlocal trace expansion coefficientsOct 03 2005Dec 19 2005In a recent work, Paycha and Scott establish formulas for all the Laurent coefficients of Tr(AP^{-s}) at the possible poles. In particular, they show a formula for the zero'th coefficient at s=0, in terms of two functions generalizing, respectively, the ... More
Computational Complexity Results for Genetic Programming and the Sorting ProblemMar 29 2011May 06 2011Genetic Programming (GP) has found various applications. Understanding this type of algorithm from a theoretical point of view is a challenging task. The first results on the computational complexity of GP have been obtained for problems with isolated ... More
On Leighton's graph covering theoremJun 13 2009May 25 2010We give short expositions of both Leighton's proof and the Bass-Kulkarni proof of Leighton's graph covering theorem, in the context of colored graphs. We discuss a further generalization, needed elsewhere, to "symmetry-restricted graphs." We can prove ... More
On the Runtime of Randomized Local Search and Simple Evolutionary Algorithms for Dynamic Makespan SchedulingApr 23 2015Evolutionary algorithms have been frequently used for dynamic optimization problems. With this paper, we contribute to the theoretical understanding of this research area. We present the first computational complexity analysis of evolutionary algorithms ... More
Immersed and virtually embedded pi_1-injective surfaces in graph manifoldsJan 21 1999Jul 10 2001We show that many 3-manifold groups have no nonabelian surface subgroups. For example, any link of an isolated complex surface singularity has this property. In fact, we determine the exact class of closed graph-manifolds which have no immersed pi_1-injective ... More
A complexity theorem for the Novelli-Pak-Stoyanovskii algorithmJun 21 2013Dec 31 2016We describe two aspects of the behaviour of entries of Young tableaux during the application of the Novelli-Pak-Stoyanovskii algorithm. We derive two theorems which both contain a generalized version of a conjecture by Krattenthaler and M\"uller concerning ... More
A topological view on algebraic computation modelsFeb 25 2016We investigate the topological aspects of some algebraic computation models, in particular the BSS-model. Our results can be seen as bounds on how different BSS-computability and computability in the sense of computable analysis can be. The framework ... More
Atiyah sequences, connections and Chern-Weil theory for algebraic and differentiable stacksNov 19 2013Nov 26 2013We construct connections and characteristic forms for principal bundles over groupoids and stacks in the differentiable, holomorphic and algebraic category using Atiyah sequences associated to transversal tangential distributions.
The Packing While Traveling ProblemDec 30 2015This paper introduces the Packing While Traveling problem as a new non-linear knapsack problem. Given are a set of cities that have a set of items of distinct profits and weights and a vehicle that may collect the items when visiting all the cities in ... More
Ideal-Chain Collapse in BiopolymersNov 29 2000Dec 18 2000A conceptual difficulty in the Hooke's-law description of ideal Gaussian polymer-chain elasticity is sometimes apparent in analyses of experimental data or in physical models designed to simulate the behavior of biopolymers. The problem, the tendency ... More
Phase Diagram for Unzipping DNA Using a Bond-Force CriterionJan 29 2002Using the criterion that the mechanical unzipping transition in a bound homopolymer is triggered when the average force exerted by the single unbound strands on the first base pair in the bound section exceeds the force binding the pair together, the ... More
Scale-invariance and contingent claim pricingJun 03 1999Prices of tradables can only be expressed relative to each other at any instant of time. This fundamental fact should therefore also hold for contigent claims, i.e. tradable instruments, whose prices depend on the prices of other tradables. We show that ... More
A short proof that positive generation implies the Hanna Neumann ConjectureFeb 13 2007We give a very short proof that a subgroup of a free group that is positively generated cannot be part of a counterexample to the Generalized Hanna Neumann Conjecture.
LightRel SemEval-2018 Task 7: Lightweight and Fast Relation ClassificationApr 19 2018We present LightRel, a lightweight and fast relation classifier. Our goal is to develop a high baseline for different relation extraction tasks. By defining only very few data-internal, word-level features and external knowledge sources in the form of ... More
Stability of steady states in kinetic Fokker-Planck equations for Bosons and FermionsJul 31 2007We study a class of nonlinear kinetic Fokker-Planck type equations modeling quantum particles which obey the Bose-Einstein and Fermi-Dirac statistics, respectively. We establish the existence of classical solutions in the perturbative regime and prove ... More
Enriching Existing Test Collections with OXPathJun 21 2017Extending TREC-style test collections by incorporating external resources is a time consuming and challenging task. Making use of freely available web data requires technical skills to work with APIs or to create a web scraping program specifically tailored ... More
Quantitative perturbative study of convergence to equilibrium for collisional kinetic models in the torusJul 21 2006For a general class of linear collisional kinetic models in the torus, including in particular the linearized Boltzmann equation for hard spheres, the linearized Landau equation with hard and moderately soft potentials and the semi-classical linearized ... More
A Feature-Based Analysis on the Impact of Set of Constraints for e-Constrained Differential EvolutionJun 23 2015Different types of evolutionary algorithms have been developed for constrained continuous optimization. We carry out a feature-based analysis of evolved constrained continuous optimization instances to understand the characteristics of constraints that ... More
A Feature-Based Comparison of Evolutionary Computing Techniques for Constrained Continuous OptimisationSep 23 2015Evolutionary algorithms have been frequently applied to constrained continuous optimisation problems. We carry out feature based comparisons of different types of evolutionary algorithms such as evolution strategies, differential evolution and particle ... More
Comment on "New formulas for the (-2) moment of the photoabsorption cross section, σ_(-2)"Jul 05 2015Mar 08 2016Empirical formulas for the second inverse moment of the photoabsorption cross sections in nuclei are discussed in J. N. Orce, Phys. Rev. C 91, 064602 (2015). In this Comment I point out that the experimental values used are systematically too small in ... More
Regular geodesic normal forms in virtually abelian groupsFeb 24 1997Cannon has given an example of a virtually abelian group and a generating set where the full language of geodesics is not regular. We describe a virtually abelian group and a generating set so that no regular language of geodesics surjects to the group. ... More
On the Humble Origins of the Brownian Entropic ForceJun 17 2015Recognition that certain forces arising from the averaging of the multiple impacts of a solute particle by the surrounding solvent particles undergoing random thermal motion can be of an entropic nature has led to the incorporation of these forces and ... More
Entropic Elasticity of Weakly Perturbed PolymersJan 22 2001Taking into account the nonequivalence of fixed-force and fixed-length ensembles in the weak-force regime, equations of state are derived that describe the equilibrium extension or compression of an ideal Gaussian polymer chain in response to an applied ... More
Absolute regularity and ergodicity of Poisson count processesJan 05 2012We consider a class of observation-driven Poisson count processes where the current value of the accompanying intensity process depends on previous values of both processes. We show under a contractive condition that the bivariate process has a unique ... More
Étale homotopy types of moduli stacks of polarised abelian schemesDec 23 2015We determine the Artin-Mazur \'etale homotopy types of moduli stacks of polarised abelian schemes using transcendental methods and derive some arithmetic properties of the \'etale fundamental groups of these moduli stacks. Finally we analyse the Torelli ... More
Finite top-mass effects in gluon-induced Higgs production with a jet-veto at NNLOAug 28 2014Effects from a finite top quark mass on the H+n-jet cross section through gluon fusion are studied for $n=0/n\ge 1$ at NNLO/NLO QCD. For this purpose, sub-leading terms in $1/m_t$ are calculated. We show that the asymptotic expansion of the jet-vetoed ... More
Etale homotopy types of moduli stacks of algebraic curves with symmetriesApr 21 2004Using the machinery of etale homotopy theory a' la Artin-Mazur we determine the etale homotopy types of moduli stacks over $\bar{\Q}$ parametrizing families of algebraic curves of genus g greater than 1 endowed with an action of a finite group G of automorphisms, ... More
A characterization of shortest geodesics on surfacesJun 24 2001Any finite configuration of curves with minimal intersections on a surface is a configuration of shortest geodesics for some Riemannian metric on the surface. The metric can be chosen to make the lengths of these geodesics equal to the number of intersections ... More
A Feature-Based Prediction Model of Algorithm Selection for Constrained Continuous OptimisationFeb 09 2016With this paper, we contribute to the growing research area of feature-based analysis of bio-inspired computing. In this research area, problem instances are classified according to different features of the underlying problem in terms of their difficulty ... More
Packing While Traveling: Mixed Integer Programming for a Class of Nonlinear Knapsack ProblemsNov 21 2014Apr 15 2015Packing and vehicle routing problems play an important role in the area of supply chain management. In this paper, we introduce a non-linear knapsack problem that occurs when packing items along a fixed route and taking into account travel time. We investigate ... More
Kleinian Groups Generated by RotationsDec 04 1997We discuss which Kleinian groups are commensurable with Kleinian groups generated by rotations, with particular emphasis on Kleinian groups that arise from Dehn surgery on a knot.
The elliptic genus of Calabi-Yau 3- and 4-folds, product formulae and generalized Kac-Moody algebrasJul 03 1996In this paper the elliptic genus for a general Calabi-Yau fourfold is derived. The recent work of Kawai calculating N=2 heterotic string one-loop threshold corrections with a Wilson line turned on is extended to a similar computation where K3 is replaced ... More
Central Extensions of Word Hyperbolic GroupsJul 13 1995Thurston has claimed (unpublished) that central extensions of word hyperbolic groups by finitely generated abelian groups are automatic. We show that they are in fact biautomatic. Further, we show that every 2-dimensional cohomology class on a word hyperbolic ... More
Parametrised second-order complexity theory with applications to the study of interval computationNov 28 2017We extend the framework for complexity of operators in analysis devised by Kawamura and Cook (2012) to allow for the treatment of a wider class of representations. The main novelty is to endow represented spaces of interest with an additional function ... More
Efficient Scene Text Localization and Recognition with Local Character RefinementApr 14 2015An unconstrained end-to-end text localization and recognition method is presented. The method detects initial text hypothesis in a single pass by an efficient region-based method and subsequently refines the text hypothesis using a more robust local text ... More
Extended Bloch group and the Cheeger-Chern-Simons classJul 08 2003Feb 15 2004We define an extended Bloch group and show it is naturally isomorphic to H_3(PSL(2,C)^\delta ;Z). Using the Rogers dilogarithm function this leads to an exact simplicial formula for the universal Cheeger-Chern-Simons class on this homology group. It also ... More
Hilbert's 3rd Problem and invariants of 3-manifoldsDec 04 1997Oct 27 1998This paper is an expansion of my lecture for David Epstein's birthday, which traced a logical progression from ideas of Euclid on subdividing polygons to some recent research on invariants of hyperbolic 3-manifolds. This `logical progression' makes a ... More
Extended Bloch group and the Chern-Simons class (Incomplete working version)Dec 10 2002We define an extended Bloch group and show it is isomorphic to $H_3(PSL(2,C)^\delta;Z)$. Using the Rogers dilogarithm function this leads to an exact simplicial formula for the universal Cheeger-Simons class on this homology group. It also leads to an ... More
Perturbative BPS-algebras in superstring theoryFeb 27 1997This paper investigates the algebraic structure that exists on perturbative BPS-states in the superstring, compactified on the product of a circle and a Calabi-Yau fourfold. This structure was defined in a recent article by Harvey and Moore. It shown ... More
Thermodynamics of a rotating black hole in minimal five-dimensional gauged supergravityFeb 24 2015In this article we study the thermodynamics of a general non-extremal rotating black hole in minimal five-dimensional gauged supergravity. We analyse the entropy-temperature diagram and the free energy. Additionally we consider the thermodynamic stability ... More
Partitioning Graph Databases - A Quantitative EvaluationJan 22 2013Electronic data is growing at increasing rates, in both size and connectivity: the increasing presence of, and interest in, relationships between data. An example is the Twitter social network graph. Due to this growth demand is increasing for technologies ... More
Large deviations for the exclusion process with a slow bondJan 01 2015Sep 11 2016We consider the one-dimensional symmetric simple exclusion process with a slow bond. In this model, whilst all the transition rates are equal to one, a particular bond, the \emph{slow bond}, has associated transition rate of value $N^{-1}$, where $N$ ... More
Incremental and Fully Dynamic Subgraph Connectivity For Emergency PlanningNov 16 2016During the last 10 years it has become popular to study dynamic graph problems in a emergency planning or sensitivity setting: Instead of considering the general fully dynamic problem, we only have to process a single batch update of size $d$; after the ... More
Realizing arithmetic invariants of hyperbolic 3-manifoldsJul 30 2011These are mostly expository notes based on the course of lectures on arithmetic invariants of hyperbolic manifolds given at the workshop associated with the final "Volume Conference," held at Columbia University, June 2009. Some new results are included. ... More
Secondary Theories for etale groupoidsJan 24 2012Generalizing Karoubi's multiplicative K-theory and multiplicative cohomology groups for smooth manifolds we define secondary theories and characteristic classes for smooth etale groupoids. As special cases we obtain versions of the groups of differential ... More