total 14097took 0.13s

Particle statistics and lossy dynamics of ultracold atoms in optical latticesSep 11 2017Experimental control over ultracold quantum gases has made it possible to investigate low-dimensional systems of both bosonic and fermionic atoms. In closed 1D systems there are a lot of similarities in the dynamics of local quantities for spinless fermions ... More

Novelty Search for Deep Reinforcement Learning Policy Network Weights by Action Sequence Edit Metric DistanceFeb 08 2019Reinforcement learning (RL) problems often feature deceptive local optima, and learning methods that optimize purely for reward signal often fail to learn strategies for overcoming them. Deep neuroevolution and novelty search have been proposed as effective ... More

On the Shuffle Automaton Size for WordsJul 29 2009We investigate the state size of DFAs accepting the shuffle of two words. We provide words u and v, such that the minimal DFA for u shuffled with v requires an exponential number of states. We also show some conditions for the words u and v which ensure ... More

From Helmut Jürgensen's Former Students: The Game of Informatics ResearchMar 07 2019Personal reflections are given on being students of Helmut J\"urgensen. Then, we attempt to address his hypothesis that informatics follows trend-like behaviours through the use of a content analysis of university job advertisements, and then via simulation ... More

Insights into Quasar UV Spectra Using Unsupervised Clustering AnalysisMar 10 2016Machine learning can provide powerful tools to detect patterns in multi-dimensional parameter space. We use K-means -a simple yet powerful unsupervised clustering algorithm which picks out structure in unlabeled data- to study a sample of quasar UV spectra ... More

On the Generalizability of Linear and Non-Linear Region of Interest-Based Multivariate Regression Models for fMRI DataFeb 03 2018In contrast to conventional, univariate analysis, various types of multivariate analysis have been applied to functional magnetic resonance imaging (fMRI) data. In this paper, we compare two contemporary approaches for multivariate regression on task-based ... More

Reservoir engineering of Cooper-pair-assisted transport with cold atomsAug 06 2019We show how Cooper-pair-assisted transport, which describes the stimulated transport of electrons in the presence of Cooper-pairs, can be engineered and controlled with cold atoms, in regimes that are difficult to access for condensed matter systems. ... More

Dynamics of many-body localization in the presence of particle lossJun 02 2017At long times residual couplings to the environment become relevant even in the most isolated experiments, creating a crucial difficulty for the study of fundamental aspects of many-body dynamics. A particular example is many-body localization in a cold-atom ... More

Floquet engineering of correlated tunneling in the Bose-Hubbard model with ultracold atomsFeb 08 2016May 18 2016We report on the experimental implementation of tunable occupation-dependent tunneling in a Bose-Hubbard system of ultracold atoms via time-periodic modulation of the on-site interaction energy. The tunneling rate is inferred from a time-resolved measurement ... More

Precision Measurements on a Tunable Mott Insulator of Ultracold AtomsJul 09 2011We perform precision measurements on a Mott-insulator quantum state of ultracold atoms with tunable interactions. We probe the dependence of the superfluid-to-Mott-insulator transition on the interaction strength and explore the limits of the standard ... More

3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive starJul 16 2019We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable lightcurves and continuum spectra for a frequency range compatible with ALMA. From these results ... More

Simulability and regularity of complex quantum systemsAug 28 2008We show that the transition from regular to chaotic spectral statistics in interacting many-body quantum systems has an unambiguous signature in the distribution of Schmidt coefficients dynamically generated from a generic initial state, and thus limits ... More

Interference of interacting matter wavesDec 28 2008The phenomenon of matter wave interference lies at the heart of quantum physics. It has been observed in various contexts in the limit of non-interacting particles as a single particle effect. Here we observe and control matter wave interference whose ... More

Observation of many-body long-range tunneling after a quantum quenchDec 10 2013Quantum tunneling constitutes one of the most fundamental processes in nature. We observe resonantly-enhanced long-range quantum tunneling in one-dimensional Mott-insulating Hubbard chains that are suddenly quenched into a tilted configuration. Higher-order ... More

Quantum quench in an atomic one-dimensional Ising chainApr 09 2013Jul 18 2013We study non-equilibrium dynamics for an ensemble of tilted one-dimensional atomic Bose-Hubbard chains after a sudden quench to the vicinity of the transition point of the Ising paramagnetic to anti-ferromagnetic quantum phase transition. The quench results ... More

Quantum trajectories and open many-body quantum systemsMay 26 2014The study of open quantum systems has become increasingly important in the past years, as the ability to control quantum coherence on a single particle level has been developed in a wide variety of physical systems. In quantum optics, the study of open ... More

Persistence of energy-dependent localization in the Anderson-Hubbard model with increasing system size and dopingJan 12 2016Non-interacting systems with bounded disorder have been shown to exhibit sharp density of states peaks at the band edge which coincide with an energy range of abruptly suppressed localization. Recent work has shown that these features also occur in the ... More

Quantum Computing and Quantum Simulation with Group-II AtomsJun 28 2011Recent experimental progress in controlling neutral group-II atoms for optical clocks, and in the production of degenerate gases with group-II atoms has given rise to novel opportunities to address challenges in quantum computing and quantum simulation. ... More

Efficient Eligibility Traces for Deep Reinforcement LearningOct 23 2018Eligibility traces are an effective technique to accelerate reinforcement learning by smoothly assigning credit to recently visited states. However, their online implementation is incompatible with modern deep reinforcement learning algorithms, which ... More

Signatures of Many-Body Localization in a Controlled Open Quantum SystemOct 05 2016In the presence of disorder, an interacting closed quantum system can undergo many-body localization (MBL) and fail to thermalize. However, over long times even weak couplings to any thermal environment will necessarily thermalize the system and erase ... More

The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical StructureMar 29 2019The vertical distribution of dust in debris disks is sensitive to the number and size of large planetesimals dynamically stirring the disk, and is therefore well-suited for constraining the prevalence of otherwise unobservable Uranus and Neptune analogs. ... More

Preparation and spectroscopy of a metastable Mott insulator state with attractive interactionsJan 04 2012We prepare and study a metastable attractive Mott insulator state formed with bosonic atoms in a three-dimensional optical lattice. Starting from a Mott insulator with Cs atoms at weak repulsive interactions, we use a magnetic Feshbach resonance to tune ... More

The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical StructureMar 29 2019Apr 08 2019The vertical distribution of dust in debris disks is sensitive to the number and size of large planetesimals dynamically stirring the disk, and is therefore well-suited for constraining the prevalence of otherwise unobservable Uranus and Neptune analogs. ... More

Interacting Fields and Flows: Magnetic Hot JupitersNov 30 2017We present Magnetohydrodynamic (MHD) simulations of the magnetic interactions between a solar type star and short period hot Jupiter exoplanets, using the publicly available MHD code PLUTO. It has been predicted that emission due to magnetic interactions ... More

Effective three-body interactions via photon-assisted tunneling in an optical latticeNov 07 2013We present a simple, experimentally realizable method to make coherent three-body interactions dominate the physics of an ultracold lattice gas. Our scheme employs either lattice modulation or laser-induced tunneling to reduce or turn off two-body interactions ... More

Winds of Massive Magnetic Stars: Interacting Fields and FlowNov 30 2017We present results of 3D numerical simulations of magnetically confined, radiatively driven stellar winds of massive stars, conducted using the astrophysical MHD code Pluto, with a focus on understanding the rotational variability of radio and sub-mm ... More

What's the value in more moments?May 11 2016The moment-based non-parametric species richness estimator of Chao is one of the most widely used estimators for the number of unobserved species in a sampling experiment. This is due in large part to its simplicity and robustness. This simplicity can ... More

A martingale view of Blackwell's renewal theorem and its extensions to a general counting processDec 18 2017Dec 24 2018Martingales constitute a basic tool in stochastic analysis; this paper considers their application to counting processes. We use this tool to revisit a renewal theorem and its extensions for various counting processes. We first consider a renewal process ... More

High velocity gas from the Galactic dark haloNov 13 1998We present the germ of a new model for High Velocity Clouds, derived from the idea that the dark matter halo of our Galaxy is in the form of cold, planetary-mass gas clouds. In this picture HVCs arise as a result of disruptive collisions between dark ... More

Order-Revealing Encryption and the Hardness of Private LearningMay 03 2015An order-revealing encryption scheme gives a public procedure by which two ciphertexts can be compared to reveal the ordering of their underlying plaintexts. We show how to use order-revealing encryption to separate computationally efficient PAC learning ... More

The Cloudy UniverseJul 20 1999Modelling of Extreme Scattering Events suggests that the Galaxy's dark matter is an undetected population of cold, AU-sized, planetary-mass gas clouds. None of the direct observational constraints on this picture -- thermal/non-thermal emission, extinction ... More

A Probabilistic Model of Compound NounsSep 06 1994Compound nouns such as example noun compound are becoming more common in natural language and pose a number of difficult problems for NLP systems, notably increasing the complexity of parsing. In this paper we develop a probabilistic model for syntactically ... More

Extreme scattering events and Galactic dark matterFeb 10 1998Mar 20 1998Extreme Scattering Events (ESEs) are attributed to radio-wave refraction by a cloud of free-electrons crossing the line-of-sight. We present a new model in which these electrons form the photo-ionized 'skin' of an underlying cool, self-gravitating cloud ... More

Thermal stability of cold clouds in galaxy halosJul 02 1999Oct 14 1999We consider the thermal properties of cold, dense clouds of molecular hydrogen and atomic helium. For cloud masses below 10^-1.7 Msun, the internal pressure is sufficient to permit the existence of particles of solid or liquid hydrogen at temperatures ... More

In-Datacenter Performance Analysis of a Tensor Processing UnitApr 16 2017Many architects believe that major improvements in cost-energy-performance must now come from domain-specific hardware. This paper evaluates a custom ASIC---called a Tensor Processing Unit (TPU)---deployed in datacenters since 2015 that accelerates the ... More

Exotic atom pairs: Repulsively bound states in an optical latticeOct 14 2006We review a recent experiment with ultracold atoms in 3D optical lattices where we have observed a novel kind of bound state of two atoms which is based on repulsive interactions between the particles. These repulsively bound pairs exhibit long lifetimes, ... More

State-dependent lattices for quantum computing with alkaline-earth-metal atomsFeb 07 2011Recent experimental progress with Alkaline-Earth atoms has opened the door to quantum computing schemes in which qubits are encoded in long-lived nuclear spin states, and the metastable electronic states of these species are used for manipulation and ... More

Atom-only descriptions of the driven-dissipative Dicke modelJan 08 2019Mar 27 2019We investigate how to describe the dissipative spin dynamics of the driven-dissipative Dicke model, describing $N$ two-level atoms coupled to a cavity mode, after adiabatic elimination of the cavity mode. To this end, we derive a Redfield master equation ... More

Andreev-like reflections with cold atomsOct 15 2007We propose a setup in which Andreev-like reflections predicted for 1D transport systems could be observed time-dependently using cold atoms in a 1D optical lattice. Using time-dependent Density Matrix Renormalisation Group methods we analyse the wavepacket ... More

Atom-only descriptions of the driven dissipative Dicke modelJan 08 2019We investigate how to describe the dissipative spin dynamics of the driven dissipative Dicke model, describing $N$ two-level atoms coupled to a cavity mode, after adiabatic elimination of the cavity mode. To this end, we derive a Redfield master equation ... More

Non-equilibrium dynamics of bosonic atoms in optical lattices: Decoherence of many-body states due to spontaneous emissionSep 01 2010We analyze in detail the heating of bosonic atoms in an optical lattice due to incoherent scattering of light from the lasers forming the lattice. Because atoms scattered into higher bands do not thermalize on the timescale of typical experiments, this ... More

Atomic matter-wave revivals with definite atom number in an optical latticeJan 12 2011We study the collapse and revival of interference patterns in the momentum distribution of atoms in optical lattices, using a projection technique to properly account for the fixed total number of atoms in the system. We consider the common experimental ... More

Time-dependent currents of 1D bosons in an optical latticeAug 18 2009Mar 03 2010We analyse the time-dependence of currents in a 1D Bose gas in an optical lattice. For a 1D system, the stability of currents induced by accelerating the lattice exhibits a broad crossover as a function of the magnitude of the acceleration, and the strength ... More

Dynamical disentangling and cooling of atoms in bilayer optical latticesSep 12 2016We show how experimentally available bilayer lattice systems can be used to prepare quantum many-body states with exceptionally low entropy in one layer, by dynamically disentangling the two layers. This disentangling operation moves one layer - subsystem ... More

The Question of Spontaneous Symmetry Breaking in CondensatesJul 27 2015The question of whether Bose-Einstein condensation involves spontaneous symmetry breaking is surprisingly controversial. We review the theory of spontaneous symmetry breaking in ferromagnets, compare it to the theory of symmetry breaking in condensates, ... More

Inhibition of the electron cyclotron maser instability in the dense magnetosphere of a hot JupiterJun 21 2018Hot Jupiter (HJ) type exoplanets are expected to produce strong radio emission in the MHz range via the Electron Cyclotron Maser Instability (ECMI). To date, no repeatable detections have been made. To explain the absence of observational results, we ... More

Two lilypond systems of finite line-segmentsMay 31 2014The paper discusses two models for non-overlapping finite line-segments constructed via the lilypond protocol, operating here on a given array of points in the plane with which are associated directions. At time 0, each line-segment starts growing at ... More

Hot Jupiter accretion: 3D MHD simulations of star-planet wind interactionDec 03 2018We present 3D MHD simulations of the wind-wind interactions between a solar type star and a short period hot Jupiter exoplanet. This is the first such simulation in which the stellar surface evolution is studied in detail. In our simulations, a planetary ... More

Model-Independent Measurement of the e+e- -> HZ Cross Section at a Future e+e- Linear Collider using Hadronic Z DecaysSep 09 2015A future e+e- collider, such as the ILC or CLIC, would allow the Higgs sector to be probed with a precision significantly beyond that achievable at the High-Luminosity LHC. A central part of the Higgs programme at an e+e- collider is the model-independent ... More

On the smallest L_2 projection of a curve in R^nDec 29 2009Jun 23 2011For a curve T:[0,1] -> R^n, we consider the directions theta in R^n which T "misses" the most and quantify this, as a function of the L_2 norm of T's differential.

Covering and distortion theorems for spirallike functions with respect to a boundary pointNov 28 2005In this note we obtain some distortion results for spirallike functions with respect to a boundary point. In particular, we find the maximal domain covered by all spirallike functions of order $\beta$.

Poor starting points in machine learningFeb 09 2016Poor (even random) starting points for learning/training/optimization are common in machine learning. In many settings, the method of Robbins and Monro (online stochastic gradient descent) is known to be optimal for good starting points, but may not be ... More

Orthogonal apartments in Hilbert Grassmannians. Finite-dimensional caseDec 23 2015Let $H$ be a complex Hilbert space of finite dimension $n\ge 3$. Denote by ${\mathcal G}_{k}(H)$ the Grassmannian consisting of $k$-dimensional subspaces of $H$. Every orthogonal apartment of ${\mathcal G}_{k}(H)$ is defined by a certain orthogonal base ... More

A non-backtracking Polya's theoremOct 15 2016P\'olya's random walk theorem states that a random walk on a $d$-dimensional grid is recurrent for $d=1,2$ and transient for $d\ge3$. We prove a version of P\'olya's random walk theorem for non-backtracking random walks. Namely, we prove that a non-backtracking ... More

Sound shell model for acoustic gravitational wave production at a first-order phase transition in the early UniverseAug 16 2016A model for the acoustic production of gravitational waves at a first order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that ... More

Classification of graph algebras: A selective surveyMar 20 2016This survey reports on current progress of programs to classify graph C*-algebras and Leavitt path algebras up to Morita equivalence using K-theory. Beginning with an overview and some history, we trace the development of the classification of simple ... More

Color superconducting quark matterFeb 05 2001May 04 2001I review recent progress in our understanding of the color superconducting phase of matter above nuclear density, giving particular emphasis to the effort to find observable signatures of the presence of this phase in compact stars.

Cosmic Variance of the Three-Point Correlation Function of the Cosmic Microwave BackgroundJun 15 1993Jul 14 1993The fluctuations in the cosmic microwave background radiation may contain deviations from gaussian statistics which would be reflected in a nonzero value of three-point correlation function of $\Delta T$. However, any potential observation of the three-point ... More

Entropy and AreaMar 09 1993Mar 20 1993The ground state density matrix for a massless free field is traced over the degrees of freedom residing inside an imaginary sphere; the resulting entropy is shown to be proportional to the area (and not the volume) of the sphere. Possible connections ... More

Status and perspectives of short baseline studiesNov 05 2009The study of flavor changing neutrinos is a very active field of research. I will discuss the status of ongoing and near term experiments investigating neutrino properties at short distances from the source. In the next few years, the Double Chooz, RENO ... More

Ex-house 2D finite-element simulation of the whispering-gallery modes of arbitrarily shaped axisymmetric electromagnetic resonatorsJul 23 2006Mar 20 2007It is described, explicitly, how a popular, commercially-available software package for solving partial-differential-equations (PDEs), as based on the finite-element method (FEM), can be configured to calculate the frequencies and fields of the whispering-gallery ... More

On the theory of symmetric polynomialsMay 09 2014May 13 2014A translation from Russian of the famous paper by Mark Krein "On the theory of symmetric polynomials" published in Math. Sb., vol. 40, no. 3, 1933, pp. 271-283.

Basic Classes of Grammars with ProhibitionFeb 21 2013A practical tool for natural language modeling and development of human-machine interaction is developed in the context of formal grammars and languages. A new type of formal grammars, called grammars with prohibition, is introduced. Grammars with prohibition ... More

Superrecursive Features of Interactive ComputationOct 08 2007Functioning and interaction of distributed devices and concurrent algorithms are analyzed in the context of the theory of algorithms. Our main concern here is how and under what conditions algorithmic interactive devices can be more powerful than the ... More

Algorithmic Problem ComplexityJul 04 2008People solve different problems and know that some of them are simple, some are complex and some insoluble. The main goal of this work is to develop a mathematical theory of algorithmic complexity for problems. This theory is aimed at determination of ... More

Hardware-Oriented Group Solutions for Hard ProblemsOct 15 2004Group and individual solutions are considered for hard problems such as satisfiability problem. Time-space trade-off in a structured active memory provides means to achieve lower time complexity for solutions of these problems.

Introduction to Projective ArithmeticsOct 15 2010Science and mathematics help people to better understand world, eliminating many inconsistencies, fallacies and misconceptions. One of such misconceptions is related to arithmetic of natural numbers, which is extremely important both for science and everyday ... More

Understanding Quaternions and the Dirac Belt TrickJan 12 2010May 29 2010The Dirac belt trick is often employed in physics classrooms to show that a $2\pi$ rotation is not topologically equivalent to the absence of rotation whereas a $4\pi$ rotation is, mirroring a key property of quaternions and their isomorphic cousins, ... More

Using the Sunyaev-Zel'dovich Effect to Probe the Gas in ClustersJul 09 2003The thermal Sunyaev-Zel'dovich effect is an important probe of clusters of galaxies, and has the attractive property of being proportional to the thermal energy content of the intracluster medium. With the assistance of X-ray data, the effect can be used ... More

Lyman Alpha Emitting Galaxies as a Probe of ReionizationJun 27 2014Aug 05 2014The Epoch of Reionization (EoR) represents a milestone in the evolution of our Universe. Star-forming galaxies that existed during the EoR likely emitted a significant fraction (~5-40%) of their bolometric luminosity as Lyman Alpha (Lya) line emission. ... More

Does Kolmogorov mean field theory become exact for turbulence above some critical dimension?Mar 25 2001I give three different arguments for an upper critical dimension $d_{max}>3$ above which the 1941 Kolmogorov mean field theory becomes essentially exact, and anomalous scaling vanishes. The first argument concerns the number of degrees of freedom in a ... More

Galilean-invariant scalar fields can strengthen gravitational lensingJan 06 2011May 16 2011The mystery of dark energy suggests that there is new gravitational physics on long length scales. Yet light degrees of freedom in gravity are strictly limited by Solar System observations. We can resolve this apparent contradiction by adding a Galilean-invariant ... More

Ordering Dynamics of Topological Defect NetworksDec 22 1997I report on some work in progress on the dynamics of extended objects in field theories after a rapid phase transition, as is relevant in the early Universe. An analytic technique, originally introduced to approximate the dynamics of topological defects ... More

Analytic scaling solutions for cosmic domain wallsMay 16 1996A relativistic generalisation of a well-known method for approximating the dynamics of topological defects in condensed matter is constructed, and applied to the evolution of domain walls in a cosmological context. It is shown that there are self-similar ... More

Where are the Hedgehogs in Nematics?Jan 09 1995In experiments which take a liquid crystal rapidly from the isotropic to the nematic phase, a dense tangle of defects is formed. In nematics, there are in principle both line and point defects (``hedgehogs''), but no point defects are observed until the ... More

Sphalerons and StringsAug 05 1994This work is based on a paper with Margaret James, to appear in Phys Rev D. In it we showed that the dipole moment of the sphaleron has its origin in two components: a ring of electric current circulating around the edge of the sphaleron; and also two ... More

Transverse nucleon structure and multiparton interactionsDec 16 2011The transverse structure of the nucleon as probed in hard exclusive processes plays critical role in the understanding of the structure of the underlying event in hard collisions at the LHC, and multiparton interactions. We summarize results of our recent ... More

Leading twist shadowing, black disk regime and forward hadron productionOct 12 2010We review theory of the leading twist nuclear shadowing, and describe phenomenon of post-selection suppression of leading parton spectrum (effective fractional energy losses) in the proximity of the black disk regime. We argue that $2 \to 2$ mechanism ... More

Quark-gluon densities in the nuclear fragmentation region in heavy ion collisions at LHCFeb 04 2006At the LHC, the leading partons in the nuclei are expected to interact with the maximal possible strength - black disk limit - up to transverse momenta of the order of few GeV. We demonstrate that in this limit the densities of the quark - gluon systems ... More

On the theory of system administrationMar 23 2000This paper describes necessary elements for constructing theoretical models of network and system administration. Armed with a theoretical model it becomes possible to determine best practices and optimal strategies in a way which objectively relates ... More

Spacetimes with Semantics (II), Scaling of agency, semantics, and tenancyMay 07 2015Using Promise Theory as a calculus, I review how to define agency in a scalable way, for the purpose of understanding semantic spacetimes. By following simple scaling rules, replacing individual agents with `super-agents' (sub-spaces), it is shown how ... More

Magnetic fields in protoplanetary disksApr 07 2007Aug 15 2007Magnetic fields likely play a key role in the dynamics and evolution of protoplanetary discs. They have the potential to efficiently transport angular momentum by MHD turbulence or via the magnetocentrifugal acceleration of outflows from the disk surface, ... More

Early Disk EvolutionDec 09 2003A variety of processes play a role in the evolution of protostellar disks. Here I focus on the uncertain issue of magnetic field-disk coupling and its implications for magnetically-driven turbulence and disk-driven winds. At present it is clear that the ... More

The Balbus-Hawley instability in weakly ionised discsSep 28 1998Mar 31 1999MHD in protostellar discs is modified by the Hall current when the ambipolar diffusion approximation breaks down. Here I examine the Balbus-Hawley (magnetorotational) instability of a weak, vertical magnetic field within a weakly-ionized disc. Vertical ... More

Metric characterization of apartments in dual polar spacesSep 10 2010Sep 14 2010Let $\Pi$ be a polar space of rank $n$ and let ${\mathcal G}_{k}(\Pi)$, $k\in \{0,\dots,n-1\}$ be the polar Grassmannian formed by $k$-dimensional singular subspaces of $\Pi$. The corresponding Grassmann graph will be denoted by $\Gamma_{k}(\Pi)$. We ... More

The Cosmological Kibble Mechanism in the Laboratory: String Formation in Liquid CrystalsOct 03 1992Nov 02 1992I report on the observation of the production of strings (disclination lines and loops) via the Kibble mechanism of domain (bubble) formation in the isotropic to nematic phase transition of a sample of uniaxial nematic liquid crystal. The probablity of ... More

Stochastic mechanics, trace dynamics, and differential space - a synthesisFeb 25 2006Mar 21 2006It is shown how Adler's trace dynamics can be applied to stochastic mechanics and other complex classical dynamical systems. Emergent non-commutivity due to the fractal nature of sample trajectories is closely related to the fact that the forward and ... More

The generalized Fenyes-Nelson model for free scalar field theoryNov 18 2002The generalized Fenyes--Nelson model of quantum mechanics is applied to the free scalar field. The resulting Markov field is equivalent to the Euclidean Markov field with the times scaled by a common factor which depends on the diffusion parameter. This ... More

Low Mass Density Wide Field Far-IR/Submillimeter Telescope SystemsJan 13 2000Fundamentally new technology is described for constructing low areal mass density (1kg/m^2), high precision (< 10micron RMS) reflectors scalable to large apertures (10 to 20 meters) for use as the primary element of a telescope system. A large reduction ... More

A Qualitative Comparison of CoQA, SQuAD 2.0 and QuACSep 27 2018In this work, we compare three datasets which build on the paradigm defined in SQuAD for question answering: SQuAD 2.0, QuAC, and CoQA. We compare these three datasets along several of their new features: (1) unanswerable questions, (2) multi-turn interactions, ... More

On Global-in-time Chaotic Weak Solutions of the Liouville Equation for Hard SpheresJul 03 2018We outline a new method of construction of global-in-time weak solutions of the Liouville equation - and also of the associated BBGKY hierarchy - corresponding to the hard sphere singular Hamiltonian. Our method makes use only of geometric reflection ... More

Designing Statistical Language Learners: Experiments on Noun CompoundsSep 25 1996The goal of this thesis is to advance the exploration of the statistical language learning design space. In pursuit of that goal, the thesis makes two main theoretical contributions: (i) it identifies a new class of designs by specifying an architecture ... More

Unified Foundations for MathematicsMar 10 2004There are different meanings of foundation of mathematics: philosophical, logical, and mathematical. Here foundations are considered as a theory that provides means (concepts, structures, methods etc.) for the development of whole mathematics. Set theory ... More

A Two Factor Forward Curve Model with Stochastic Volatility for Commodity PricesAug 04 2017Aug 08 2017We describe a model for evolving commodity forward prices that incorporates three important dynamics which appear in many commodity markets: mean reversion in spot prices and the resulting Samuelson effect on volatility term structure, decorrelation of ... More

Stochastic Spot/Volatility Correlation in Stochastic Volatility Models and Barrier Option PricingApr 15 2014Most models for barrier pricing are designed to let a market maker tune the model-implied covariance between moves in the asset spot price and moves in the implied volatility skew. This is often implemented with a local volatility/stochastic volatility ... More

Evolution of Systems with Power-Law Memory: Do We Have to Die?Apr 30 2019Various features of the development of individual living species, including individual humans, are programmed. Is death also programmed, and if yes, how is it implemented and what can be the underlying mechanism providing the inevitability of death? The ... More

Small components in k-nearest neighbour graphsJan 13 2011Let $G=G_{n,k}$ denote the graph formed by placing points in a square of area $n$ according to a Poisson process of density 1 and joining each point to its $k$ nearest neighbours. Balister, Bollob\'as, Sarkar and Walters proved that if $k<0.3043\log n$ ... More

A cyclage poset structure for Littlewood-Richardson tableauxApr 07 1998A graded poset structure is defined for the sets of Littlewood-Richardson (LR) tableaux that count the multiplicity of an irreducible GL(n)-module in the tensor product of irreducibles indexed by a sequence of rectangular partitions. This poset generalizes ... More

Multi-atoms and monotonicity of generalized Kostka polynomialsApr 07 1998The generalized Kostka polynomials are the Poincare polynomials of isotypic components of certain graded GL(n)-modules. The former satisfy a monotonicity property arising from natural surjections of the corresponding modules. This monotonicity property ... More