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Results for "Magnus T. Koudahl"

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Ergodicity-breaking reveals time optimal economic behavior in humansJun 11 2019Jun 12 2019Ergodicity describes an equivalence between the expectation value and the time average of observables. Applied to human behaviour, ergodic theory reveals how individuals should tolerate risk in different environments. To optimise wealth over time, agents ... More
Asynchronous Multi-Agent Primal-Dual OptimizationJun 07 2016We present a framework for asynchronously solving nonlinear optimization problems over networks of agents which are augmented by the presence of a centralized cloud computer. This framework uses a Tikhonov-regularized primal-dual approach in which the ... More
Recovering tree-child networks from shortest inter-taxa distance informationNov 24 2017Phylogenetic networks are a type of leaf-labelled, acyclic, directed graph used by biologists to represent the evolutionary history of species whose past includes reticulation events. A phylogenetic network is tree-child if each non-leaf vertex is the ... More
Ergodicity-breaking reveals time optimal economic behavior in humansJun 11 2019Ergodicity describes an equivalence between the expectation value and the time average of observables. Applied to human behaviour, ergodic theory reveals how individuals should tolerate risk in different environments. To optimise wealth over time, agents ... More
Operator-valued pseudo-differential operators and the twisted index pairingNov 26 2010Nov 10 2011The notion of pseudo-differential operators with coefficients in a continuous trace algebra over a manifold are introduced and their index theory is studied. The algebra of principal symbols in this calculus provides an abstract Poincar\'e dual to the ... More
On the Finite Horizon Optimal Switching Problem with Random LagAug 24 2018We consider an optimal switching problem with random lag and possibility of component failure. The random lag is modeled by letting the operation mode follow a regime switching Markov-model with transition intensities that depend on the switching mode. ... More
Directable Fuzzy and Nondeterministic AutomataSep 22 2017We study three notions of directability of fuzzy automata akin to the D1-, D2- and D3-directability of nondeterministic automata. Thus an input word $w$ of a fuzzy automaton is D1-directing if a fixed single state is reachable by $w$ from all states, ... More
Initial-Boundary Value Problems for Parabolic EquationsSep 19 2008We prove new existence and uniqueness results for weak solutions to non-homogeneous initial-boundary value problems for parabolic equations modeled on the evolution of the p-Laplacian.
A Finite Horizon Optimal Switching Problem with Memory and Application to Controlled SDDEsMay 22 2019We consider an optimal switching problem where the terminal reward depends on the entire control trajectory. We show existence of an optimal control by applying a probabilistic technique based on the concept of Snell envelopes. We then apply this result ... More
Temperature dependence of an Efimov resonance in $^{39}\mathrm{K}$Jul 13 2018Nov 27 2018Ultracold atomic gases are an important testing ground for understanding few-body physics. In particular, these systems enable a detailed study of the Efimov effect. We use ultracold $^{39}\mathrm{K}$ to investigate the temperature dependence of an Efimov ... More
Parameterized Algorithms for Zero Extension and Metric Labelling ProblemsFeb 16 2018We consider the problems ZERO EXTENSION and METRIC LABELLING under the paradigm of parameterized complexity. These are natural, well-studied problems with important applications, but have previously not received much attention from parameterized complexity. ... More
Tree AutomataSep 21 2015This is a reissue of the book Tree Automata by F. G\'ecseg and M. Steinby originally published in 1984 by Akad\'emiai Kiad\'o, Budapest. Some mistakes have been corrected and a few obscure passages have been clarified. Moreover, some more recent contributions ... More
Reticulation-visible networksAug 21 2015Jun 25 2017Let $X$ be a finite set, $\mathcal N$ be a reticulation-visible network on $X$, and $\mathcal T$ be a rooted binary phylogenetic tree. We show that there is a polynomial-time algorithm for deciding whether or not $\mathcal N$ displays $\mathcal T$. Furthermore, ... More
Simplified a priori Estimate for the Time Periodic Burgers' EquationMay 03 2012We present here a version of the existence and uniqueness result of time periodic solutions to the viscous Burgers equation with irregular forcing terms (with Sobolev regularity -1 in space). The key result here is an a priori estimate which is simpler ... More
Independent resolutions for totally disconnected dynamical systems I: Algebraic caseApr 24 2014Sep 22 2014This is the first out of two papers on independent resolutions for totally disconnected dynamical systems. In the present paper, we discuss independent resolutions from an algebraic point of view. We also present applications to group homology and cohomology. ... More
Rapid mixing of subset Glauber dynamics on graphs of bounded tree-widthFeb 17 2011Motivated by the `subgraphs world' view of the ferromagnetic Ising model, we develop a general approach to studying mixing times of Glauber dynamics based on subset expansion expressions for a class of graph polynomials. With a canonical paths argument, ... More
Empirical Big Data Research: A Systematic Literature MappingSep 10 2015Background: Big Data is a relatively new field of research and technology, and literature reports a wide variety of concepts labeled with Big Data. The maturity of a research field can be measured in the number of publications containing empirical results. ... More
Latent modeling of flow cytometry cell populationsFeb 13 2015Flow cytometry is a widespread single-cell measurement technology with a multitude of clinical and research applications. Interpretation of flow cytometry data is hard; the instrumentation is delicate and can not render absolute measurements, hence samples ... More
Clusters of eigenvalues for the magnetic Laplacian with Robin conditionJun 04 2014We study the Schr\"{o}dinger operator with a constant magnetic field in the exterior of a compact domain in euclidean space. Functions in the domain of the operator are subject to a boundary condition of the third type (a magnetic Robin condition). In ... More
Fast simulated annealing in $\R^d$ and an application to maximum likelihood estimationSep 13 2006Using classical simulated annealing to maximise a function $\psi$ defined on a subset of $\R^d$, the probability $\p(\psi(\theta\_n)\leq \psi\_{\max}-\epsilon)$ tends to zero at a logarithmic rate as $n$ increases; here $\theta\_n$ is the state in the ... More
3D sub-nanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin filmsOct 17 2018Oct 24 2018Determining the 3-dimensional crystallography of a material with sub-nanometre resolution is essential to understanding strain effects in epitaxial thin films. A new scanning transmission electron microscopy imaging technique is demonstrated that visualises ... More
Convergence Rate Estimates for Consensus over Random GraphsOct 21 2016Multi-agent coordination algorithms with randomized interactions have seen use in a variety of settings in the multi-agent systems literature. In some cases, these algorithms can be random by design, as in a gossip-like algorithm, and in other cases they ... More
Cotorsion torsion triples and the representation theory of filtered hierarchical clusteringApr 15 2019We give a full classification of representation types of the subcategories of representations of an $m \times n$ rectangular grid with monomorphisms (dually, epimorphisms) in one or both directions, which appear naturally in the context of clustering ... More
Multi-budgeted directed cutsOct 16 2018We study multi-budgeted variants of the classic minimum cut problem and graph separation problems that turned out to be important in parameterized complexity: Skew Multicut and Directed Feedback Arc Set. In our generalization, we assign colors $1,2,...,\ell$ ... More
Cloud-Based Centralized/Decentralized Multi-Agent Optimization with Communication DelaysAug 25 2015We present and analyze a computational hybrid architecture for performing multi-agent optimization. The optimization problems under consideration have convex objective and constraint functions with mild smoothness conditions imposed on them. For such ... More
Investigation of force approximations in tethered cells simulationsAug 11 2015Simulations of tethered cells in viscous sub-layers are frequently performed using the Stokes drag force, but without taking into account contributions from surface corrections, lift forces, buoyancy, the Basset force, the cells finite inertia, or added ... More
Inferring the perturbation time from biological time course dataFeb 04 2016Time course data are often used to study the changes to a biological process after perturbation. Statistical methods have been developed to determine whether such a perturbation induces changes over time, e.g. comparing a perturbed and unperturbed time ... More
Alternative parameterizations of Metric DimensionApr 27 2018A set of vertices $W$ in a graph $G$ is called resolving if for any two distinct $x,y\in V(G)$, there is $v\in W$ such that ${\rm dist}_G(v,x)\neq{\rm dist}_G(v,y)$, where ${\rm dist}_G(u,v)$ denotes the length of a shortest path between $u$ and $v$ in ... More
Data Dissemination in Unified Dynamic Wireless NetworksMay 09 2016We give efficient algorithms for the fundamental problems of Broadcast and Local Broadcast in dynamic wireless networks. We propose a general model of communication which captures and includes both fading models (like SINR) and graph-based models (such ... More
Asynchronous Multi-Agent Primal-Dual OptimizationJun 07 2016Oct 13 2016We present a framework for asynchronously solving convex optimization problems over networks of agents which are augmented by the presence of a centralized cloud computer. This framework uses a Tikhonov-regularized primal-dual approach in which the agents ... More
ToxTrac: a fast and robust software for tracking organismsJun 08 20171. Behavioral analysis based on video recording is becoming increasingly popular within research fields such as; ecology, medicine, ecotoxicology, and toxicology. However, the programs available to analyze the data, which are; free of cost, user-friendly, ... More
Quantum limited particle sensing in optical tweezersJul 24 2009Particle sensing in optical tweezers systems provides information on the position, velocity and force of the specimen particles. The conventional quadrant detection scheme is applied ubiquitously in optical tweezers experiments to quantify these parameters. ... More
Dynamic properties of bacterial pili measured by optical tweezersNov 06 2014The ability of uropathogenic Escherichia coli (UPEC) to cause urinary tract infections is dependent on their ability to colonize the uroepithelium. Infecting bacteria ascend the urethra to the bladder and then kidneys by attaching to the uroepithelial ... More
Control Barrier Functions: Theory and ApplicationsMar 27 2019This paper provides an introduction and overview of recent work on control barrier functions and their use to verify and enforce safety properties in the context of (optimization based) safety-critical controllers. We survey the main technical results ... More
CO Observations of the Interacting Galaxy Pair NGC 5394/95Nov 13 2001BIMA CO 1-0 observations are presented of the spiral galaxies NGC 5394 and NGC 5395 that have undergone a recent, grazing encounter. In NGC 5394, 80% of the CO emission detected by BIMA is concentrated in the central 800 pc (FWHM) starburst region.In ... More
Enabling high spectral efficiency coherent superchannel transmission with soliton microcombsDec 22 2018Optical communication systems have come through five orders of magnitude improvement in data rate over the last three decades. The increased demand in data traffic and the limited optoelectronic component bandwidths have led to state-of-the-art systems ... More
Hamiltonian Hopf bifurcations in the discrete nonlinear Schrödinger trimer: oscillatory instabilities, quasiperiodic solutions and a 'new' type of self-trapping transitionJul 30 2003Jan 08 2004Oscillatory instabilities in Hamiltonian anharmonic lattices are known to appear through Hamiltonian Hopf bifurcations of certain time-periodic solutions of multibreather type. Here, we analyze the basic mechanisms for this scenario by considering the ... More
The dual nest for degenerate Yoccoz puzzlesApr 08 2009The Yoccoz puzzle is a fundamental tool in Holomorphic Dynamics. The original combinatorial argument by Yoccoz, based on the Branner-Hubbard tableau, counts the preimages of a non-degenerate annulus in the puzzle. However, in some important new applications ... More
Current-voltage relation for superconducting d-wave junctionsFeb 03 1997We calculate the current-voltage (I-V) relation for planar superconducting d-wave junctions for both arbitrary transmission of the junction and arbitrary orientation of the d-wave superconductors. The midgap states (MGS) present at interfaces/surfaces ... More
Equivariant extensions of *-algebrasMar 30 2010Nov 07 2010A bivariant functor is defined on a category of *-algebras and a category of operator ideals, both with actions of a second countable group $G$, into the category of abelian monoids. The element of the bivariant functor will be $G$-equivariant extensions ... More
Rational Misiurewicz maps for which the Julia set is not the whole sphereJun 26 2009We show that Misiurewicz maps for which the Julia set is not the whole sphere are Lebesgue density points of hyperbolic maps.
Static spacetimes with prescribed multipole moments; a proof of a conjecture by GerochJun 23 2009In this paper we give sufficient conditions on a sequence of multipole moments for a static spacetime to exist with precisely these moments. The proof is constructive in the sense that a metric having prescribed multipole moments up to a given order can ... More
Stochastic trapping in a solvable model of on-line independent component analysisMay 03 2001Previous analytical studies of on-line Independent Component Analysis (ICA) learning rules have focussed on asymptotic stability and efficiency. In practice the transient stages of learning will often be more significant in determining the success of ... More
Abusing the Tutte Matrix: An Algebraic Instance Compression for the K-set-cycle ProblemJan 08 2013We give an algebraic, determinant-based algorithm for the K-Cycle problem, i.e., the problem of finding a cycle through a set of specified elements. Our approach gives a simple FPT algorithm for the problem, matching the $O^*(2^{|K|})$ running time of ... More
Bridgeland stability conditions on twisted Kummer surfacesJan 27 2012Sep 19 2012We construct a topological embedding of the maximal connected component of Bridgeland stability conditions of a (twisted) Abelian surface into the distinguished connected component of the stability manifold of the associated (twisted) Kummer surface. ... More
Analytic formulas for topological degree of non-smooth mappings: the odd-dimensional caseApr 07 2010The notion of topological degree is studied for mappings from the boundary of a relatively compact strictly pseudo-convex domain in a Stein manifold into a manifold in terms of index theory of Toeplitz operators on the Hardy space. The index formalism ... More
Algorithms for Grey-Weighted Distance ComputationsMay 08 2019With the increasing size of datasets and demand for real time response for interactive applications, improving runtime for algorithms with excessive computational requirements has become increasingly important. Many different algorithms combining efficient ... More
The connection between polarization calculus and four-dimensional rotationsMar 07 2013We review the well-known polarization optics matrix methods, i.e., Jones and Stokes-Mueller calculus, and show how they can be formulated in terms of four-dimensional (4d) rotations of the four independent electromagnetic field quadratures. Since 4d rotations ... More
Twinning superlattices in indium phosphide nanowiresJul 09 2008Here, we show that we control the crystal structure of indium phosphide (InP) nanowires by impurity dopants. We have found that zinc decreases the activation barrier for 2D nucleation growth of zinc-blende InP and therefore promotes the InP nanowires ... More
Analytic formulas for topological degree of non-smooth mappings: the even-dimensional caseJun 20 2010Feb 09 2013Topological degrees of continuous mappings between manifolds of even dimension are studied in terms of index theory of pseudo-differential operators. The index formalism of non-commutative geometry is used to derive analytic integral formulas for the ... More
A Limited-Feedback Approximation Scheme for Optimal Switching Problems with Execution DelaysMay 02 2016Sep 22 2016We consider a type of optimal switching problems with non-uniform execution delays and ramping. Such problems frequently occur in the operation of economical and engineering systems. We first provide a solution to the problem by applying a probabilistic ... More
Khovanov's conjecture over Z[c]Aug 15 2003We disprove the conjecture of M. Khovanov (math.QA/9908171) on the functoriality of his link homology with polynomial coefficients. This is in contrast to the case of integer coefficients, where functoriality was proved in math.GT/0206303 .
The Pimsner-Voiculescu sequence for coactions of compact Lie groupsApr 25 2010Mar 02 2011The Pimsner-Voiculescu sequence is generalized to a Pimsner-Voiculescu tower describing the $KK$-category equivariant with respect to coactions of a compact Lie group satisfying the Hodgkin condition. A dual Pimsner-Voiculescu tower is used to show that ... More
Continuous-Variable Spatial Entanglement for Bright Optical BeamsJan 25 2005A light beam is said to be position squeezed if its position can be determined to an accuracy beyond the standard quantum limit. We identify the position and momentum observables for bright optical beams and show that position and momentum entanglement ... More
Maximal green sequences for preprojective algebrasApr 08 2015May 26 2015Maximal green sequences were introduced as combinatorical counterpart for Donaldson-Thomas invariants for 2-acyclic quivers with potential by B. Keller. We take the categorical notion and introduce maximal green sequences for hearts of bounded t-structures ... More
Phases of stable representations of quiversNov 27 2014We consider stable representations of non-Dynkin quivers with respect to a central charge. On one condition the existence of a stable representation with self-extensions implies the existence of infinitely many stables without self-extensions. In this ... More
A remark on twists and the notion of torsion-free discrete quantum groupsApr 01 2010Jan 31 2011In this paper twists of reduced locally compact quantum groups are studied. Twists of the dual coaction on a reduced crossed product are introduced and the twisted dual coactions are proved to satisfy a type of Takesaki-Takai duality. The twisted Takesaki-Takai ... More
Perturbations of rational Misiurewicz mapsApr 07 2008Jun 22 2009In this paper we investigate the perturbation properties of rational Misiurewicz maps, when the Julia set is the whole sphere (the other case is treated in [1]). In particular, we show that if f is a Misiurewicz map and not a flexible Lattes map, then ... More
LP-branching algorithms based on biased graphsOct 19 2016We give a combinatorial condition for the existence of efficient, LP-based FPT algorithms for a broad class of graph-theoretical optimisation problems. Our condition is based on the notion of biased graphs known from matroid theory. Specifically, we show ... More
Semi-hyperbolic maps are rareMay 19 2016We prove in this paper that the set of semi-hyperbolic rational maps has Lebesgue measure zero in the space of rational maps of the Riemann sphere for a fixed degree d at least 2. It generalises an earlier result by J. Graczyk and the author who proved ... More
A Control-variable Regression Monte Carlo Technique for Short-term Electricity Generation PlanningDec 30 2015In the day-to-day operation of a power system, the system operator repeatedly solves short-term generation planning problems. When formulating these problems the operators have to weigh the risk of costly failures against increased production costs. The ... More
Tilting and Refined Donaldson-Thomas InvariantsMar 25 2013Mar 06 2014We study tilting for the heart A of the canonical t-structure of the finite-dimensional derived category of the Ginzburg algebra for a quiver with potential (Q,W). We give conditions on that the stable objects for a central charge on A define a sequence ... More
Index formulas and charge deficiencies on the Landau levelsMar 15 2010The notion of charge deficiency from Avron, Seiler, Simon (Charge deficiency, charge transport and comparison of dimensions, Comm. Math. Phys. 159) is studied from the view of $KK$-theory and is applied to the Landau levels in $\C^n$. We calculate the ... More
Rational Misiurewicz maps are rareJan 13 2007Mar 11 2007We show that the set of Misiurewicz maps has Lebesgue measure zero in the parameter space of rational maps for any fixed degree greater than or equal to 2.
On the differentiability conditions at spacelike infinityDec 12 1997We consider space-times which are asymptotically flat at spacelike infinity, i^0. It is well known that, in general, one cannot have a smooth differentiable structure at i^0, but have to use direction dependent structures. Instead of the oftenly used ... More
Rational Misiurewicz maps are rare IIMar 11 2007Feb 11 2008We show that the set of Misiurewicz maps has Lebesgue measure zero in the space of rational functions for any fixed degree greater than or equal to 2 (generalising the earlier version math.DS/0701382).
An invariant of link cobordisms from Khovanov homologyJun 28 2002Dec 23 2004In [Duke Math. J. 101 (1999) 359-426], Mikhail Khovanov constructed a homology theory for oriented links, whose graded Euler characteristic is the Jones polynomial. He also explained how every link cobordism between two links induces a homomorphism between ... More
Shared matings in $V_2$Dec 22 2016Jan 09 2017We give a new constructive method to prove existence of shared matings in the special class $V_2$ consisting of rational maps with a super-attracting $2$-cycle (up to M\"obius conjugacy). The proof does not use Thurston's Theorem on branched coverings ... More
Statistical and knowledge supported visualization of multivariate dataAug 31 2010In the present work we have selected a collection of statistical and mathematical tools useful for the exploration of multivariate data and we present them in a form that is meant to be particularly accessible to a classically trained mathematician. We ... More
A Limited-Feedback Approximation Scheme for Optimal Switching Problems with Execution DelaysMay 02 2016Feb 14 2017We consider a type of optimal switching problems with non-uniform execution delays and ramping. Such problems frequently occur in the operation of economical and engineering systems. We first provide a solution to the problem by applying a probabilistic ... More
Modified Artificial Viscosity in Smooth Particle HydrodynamicsDec 05 1996Dec 12 1996Artificial viscosity is needed in Smooth Particle Hydrodynamics to prevent interparticle penetration, to allow shocks to form and to damp post shock oscillations. Artificial viscosity may, however, lead to problems such as unwanted heating and unphysical ... More
The Use of Non-Spherical Kernels in Smooth Particle HydrodynamicsJun 07 1997A general expression for the momentum equation in the Smooth Particle Hydrodynacis approximation is derived for an arbitrary kernel, and compared with its spherical counterpart for various degrees of ellipsoidicity. For such an ellsipsoidal kernel the ... More
New insights in brane and Kaluza--Klein theory through almost product structuresDec 18 1998We will show that gauge theory can be described by an almost product structure, which is a certain type of endomorphism of the tangent bundle. We will recover the gauge field strength as the Nijenhuis tensor of this endomorphism. We discuss a generalization ... More
Decay of DNLS breathers through inelastic multiphonon scatteringDec 28 2000We consider the long-time evolution of weakly perturbed discrete nonlinear Schroedinger breathers. While breather growth can occur through nonlinear interaction with one single initial linear mode, breather decay is found to require excitation of at least ... More
Construction of force measuring optical tweezers instrumentation and investigations of biophysical properties of bacterial adhesion organellesMar 03 2015Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in the field of ... More
Intersubband Quantum Disc-in-Nanowire Photodetectors with Normal-incidence Response in the Long-wavelength InfraredSep 10 2017Semiconductor nanowires offer great potential for realizing broadband photodetectors that are compatible with silicon technology. However, the spectral range of such detectors has so far been limited to selected regions in the ultraviolet, visible and ... More
Optimum Small Optical Beam Displacement MeasurementJul 27 2004We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with 80% efficiency. We propose a new ... More
Diameter-dependent conductance of InAs nanowiresDec 22 2009Electrical conductance through InAs nanowires is relevant for electronic applications as well as for fundamental quantum experiments. Here we employ nominally undoped, slightly tapered InAs nanowires to study the diameter dependence of their conductance. ... More
Molecular complexity on disk-scales uncovered by ALMA: The chemical composition of the high-mass protostar AFGL 4176Jun 14 2019The chemical composition of high-mass protostars reflects the physical evolution associated with different stages of star formation. In this study, the molecular inventory of the forming high-mass star AFGL 4176 is studied in detail at high angular resolution ... More
Giant optical birefringence of semiconductor nanowire metamaterialsApr 26 2006Semiconductor nanowires exhibit large polarization anisotropy for the absorption and emission of light, making them ideal building blocks for novel photonic metamaterials. Here, we demonstrate that a high density of aligned nanowires exhibits giant optical ... More
The Dynamics of a Genetic Algorithm for a Simple Learning ProblemSep 12 1996A formalism for describing the dynamics of Genetic Algorithms (GAs) using methods from statistical mechanics is applied to the problem of generalization in a perceptron with binary weights. The dynamics are solved for the case where a new batch of training ... More
Inverse Ising inference using all the dataJul 18 2011Nov 12 2012We show that a method based on logistic regression, using all the data, solves the inverse Ising problem far better than mean-field calculations relying only on sample pairwise correlation functions, while still computationally feasible for hundreds of ... More
Quantum diffusion: a simple, exactly solvable modelDec 06 2012We propose a simple quantum mechanical model describing the time dependent diffusion current between two fermion reservoirs that were initially disconnected and characterized by different densities or chemical potentials. The exact, analytical solution ... More
Signs of magnetic acceleration and multi-zone emission in GRB 080825CFeb 25 2016One of the major results from the study of gamma-ray bursts with the Fermi Gamma-ray Space Telescope has been the confirmation that several emission components can be present in the energy spectrum. Here we reanalyse the spectrum of GRB 080825C using ... More
Anticipatory Guidance of PlotJun 26 2002Feb 19 2003An anticipatory system for guiding plot development in interactive narratives is described. The executable model is a finite automaton that provides the implemented system with a look-ahead. The identification of undesirable future states in the model ... More
Agent trade servers in financial exchange systemsMar 19 2002New services based on the best-effort paradigm could complement the current deterministic services of an electronic financial exchange. Four crucial aspects of such systems would benefit from a hybrid stance: proper use of processing resources, bandwidth ... More
On the Complexity of Computing Two Nonlinearity MeasuresMar 03 2014We study the computational complexity of two Boolean nonlinearity measures: the nonlinearity and the multiplicative complexity. We show that if one-way functions exist, no algorithm can compute the multiplicative complexity in time $2^{O(n)}$ given the ... More
Static axisymmetric space-times with prescribed multipole momentsFeb 03 2005In this article we develop a method of finding the static axisymmetric space-time corresponding to any given set of multipole moments. In addition to an implicit algebraic form for the general solution, we also give a power series expression for all finite ... More
Painlevé-type differential equations for the recurrence coefficients of semi-classical orthogonal polynomials.Jul 09 1993Recurrence coefficients of semi-classical orthogonal polynomials (orthogonal polynomials related to a weight function $w$ such that $w'/w$ is a rational function) are shown to be solutions of non linear differential equations with respect to a well-chosen ... More
Calculation of, and bounds for, the multipole moments of stationary spacetimesJun 27 2006In this paper the multipole moments of stationary asymptotically flat spacetimes are considered. We show how the tensorial recursion of Geroch and Hansen can be replaced by a scalar recursion on R^2. We also give a bound on the multipole moments. This ... More
Coupling of ion and network dynamics in lithium silicate glasses: a computer studyJan 25 2005We present a detailed analysis of the ion hopping dynamics and the related nearby oxygen dynamics in a lithium meta silicate glass via molecular dynamics simulation. For this purpose we have developed numerical techniques to identify ion hops and to sample ... More
A simple harmonic model as a caricature for mismatch and relaxation effects for ion hopping dynamics in solid electrolytesMay 02 2003We formulate a simple harmonic mean-field model with N+1 particles and analyse the relaxation processes following a jump of one of these particles. Either the particle can jump back (single-particle route) or the other N particles adjust themselves (multi-particle ... More
Cloud-Based Optimization: A Quasi-Decentralized Approach to Multi-Agent CoordinationApr 01 2014Sep 23 2014New architectures and algorithms are needed to reflect the mixture of local and global information that is available as multi-agent systems connect over the cloud. We present a novel architecture for multi-agent coordination where the cloud is assumed ... More
Spectral triples on $O_N$Oct 05 2016We give a construction of an odd spectral triple on the Cuntz algebra $O_{N}$, whose class generates $K^1(O_{N})$. Using a metric measure space structure on the Cuntz-Renault groupoid, we introduce a singular integral operator which is the formal analogue ... More
Curvature relations in almost product manifoldsApr 14 1999New relations involving curvature components for the various connections appearing in the theory of almost product manifolds are given and the conformal behaviour of these connections are studied. New identities for the irreducible parts of the deformation ... More
Safe Open-Loop Strategies for Handling Intermittent Communications in Multi-Robot SystemsFeb 11 2017In multi-robot systems where a central decision maker is specifying the movement of each individual robot, a communication failure can severely impair the performance of the system. This paper develops a motion strategy that allows robots to safely handle ... More
On the magnitude function of domains in Euclidean spaceJun 21 2017Nov 21 2017We study Leinster's notion of magnitude for a compact metric space. For a smooth, compact domain $X\subset \mathbb{R}^{2m-1}$, we find geometric significance in the function $\mathcal{M}_X(R) = \mathrm{mag}(R\cdot X)$. The function $\mathcal{M}_X$ extends ... More
Coverage Control for Wire-Traversing RobotsFeb 24 2018In this paper we consider the coverage control problem for a team of wire-traversing robots. The two-dimensional motion of robots moving in a planar environment has to be projected to one-dimensional manifolds representing the wires. Starting from Lloyd's ... More
Mating non-renormalizable quadratic polynomialsOct 10 2006Mar 25 2009In this paper we prove the existence and uniqueness of matings of the basilica with any quadratic polynomial which lies outside of the 1/2-limb of M, is non-renormalizable, and does not have any non-repelling periodic orbits.