Results for "Finn Rabe"

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A Query Language for Formal Mathematical LibrariesApr 20 2012One of the most promising applications of mathematical knowledge management is search: Even if we restrict attention to the tiny fragment of mathematics that has been formalized, the amount exceeds the comprehension of an individual human. Based on the ... More
Tunability of High-Dielectric-Constant Materials from First PrinciplesMay 30 2002A first-principles method, based on density functional perturbation theory, is presented for computing the leading order tunability of high-dielectric-constant materials.
A Scalable Module SystemMay 03 2011Symbolic and logic computation systems ranging from computer algebra systems to theorem provers are finding their way into science, technology, mathematics and engineering. But such systems rely on explicitly or implicitly represented mathematical knowledge ... More
Oskar Klein and the fifth dimensionSep 16 2013After a short biographical summary of the scientific life of Oskar Klein, a more detailed and hopefully didactic presentation of his derivation of the relativistic Klein-Gordon wave equation is given. It was a result coming out of his unification of electromagnetism ... More
Symmetric and conserved energy-momentum tensors in moving mediaJul 25 2011Sep 09 2011A symmetric and conserved energy-momentum tensor for a scalar field in a moving medium is derived using the Gordon metric. When applied to an electromagnetic field, the method gives a similar result. This approach thus points a way out of the old Abraham-Minkowski ... More
Fibrations of predicates and bicategories of relationsFeb 27 2015We reconcile the two different category-theoretic semantics of regular theories in predicate logic. A 2-category of `regular fibrations' is constructed, as well as a 2-category of `regular proarrow equipments', and it is shown that the two are equivalent. ... More
How I got to work with Feynman on the covariant quark modelNov 03 2014In the period 1968 - 1974 I was a graduate student and then a postdoc at Caltech and was involved with the developments of the quark and parton models. Most of this time I worked in close contact with Richard Feynman and thus was present from the parton ... More
Electromagnetism and photons in continuous mediaOct 10 2008Different theoretical and experimental aspects of electromagnetic phenomena in media is reviewed. The 100 year old Minkowski theory is in agreement with most experiments, but has theoretical problems related to its implied validity in all inertial frames. ... More
Rotating Kaluza-Klein Black HolesSep 15 1999Feb 04 2000All regular four-dimensional black holes are constructed in the theory obtained by Kaluza-Klein reduction of five-dimensional Einstein gravity. They are interpreted in string theory as rotating bound states of D0- and D6-branes. Conservation of angular ... More
The Perturbation Spectrum of Black Holes in N=8 SupergravityMay 28 1998Jun 14 1998The near horizon geometry of four-dimensional black holes in the dilute gas regime is AdS_3 x S^2, and the global symmetry group is SU(2) x USp(6). This is exploited to calculate their perturbation spectrum using group theoretical methods. The result ... More
Unreasonable Effectivness of Deep LearningMar 28 2018We show how well known rules of back propagation arise from a weighted combination of finite automata. By redefining a finite automata as a predictor we combine the set of all $k$-state finite automata using a weighted majority algorithm. This aggregated ... More
Resolving Gravitational SingularitiesAug 06 2008We review recent progress on the resolution of gravitational singularities in string theory. The main example is the fundamental string in five dimensions which is singular in the standard supergravity description but regular after taking into account ... More
Problems with the Casimir Vacuum EnergySep 18 2000A critical look is taken at the calculation of the Casimir effect. The boundary conditions play an important role and should be imposed in a physical way. An acceptable result for the vacuum energy is only obtained when different regularization schemes ... More
Radiative Corrections to the Stefan-Boltzmann LawSep 02 1997Photons in blackbody radiation have non-zero interactions due to their couplings to virtual electron-positron pairs in the vacuum. For temperatures much less than the electron mass $m$ these effects can be described by an effective theory incorporating ... More
The Attractor Mechanism in Five DimensionsAug 28 2006We give a pedagogical introduction to the attractor mechanism. We begin by developing the formalism for the simplest example of spherically symmetric black holes in five dimensions which preserve supersymmetry. We then discuss the refinements needed when ... More
Scalar Gravitation and Extra DimensionsMay 06 2004Gunnar Nordstrom constructed the first relativistic theory of gravitation formulated in terms of interactions with a scalar field. It was an important precursor to Einstein's general theory of relativity a couple of years later. He was also the first ... More
Kaluza-Klein Black Holes in String TheoryFeb 21 2000Non-supersymmetric black holes carrying both electric and magnetic charge with respect to a single Kaluza-Klein gauge field have much in common with supersymmetric black holes. Angular momentum conservation and other general physics principles underlies ... More
Electromagnetic energy-momentum tensors in mediaMay 16 2008Sep 30 2008It is pointed out that the previous energy-momentum tensors of Minkowski and Abraham for the electromagnetic field in continuous media are based on a covariant formulation which does not reflect a symmetry inherent to the system. Instead, taking into ... More
Fundamental Strings as Noncommutative SolitonsOct 20 2000The interpretation of closed fundamental strings as solitons in open string field theory is reviewed. Noncommutativity is introduced to facilitate an explicit construction. The tension is computed exactly and the correct spectrum is recovered at long ... More
Effective Field Theory of QED Vacuum FluctuationsJun 10 1998Jun 18 1998Plenary talk at PASCOS-98, Boston, Massachusetts, USA, March 22-29, 1998.
Anti-DeSitter Spaces and Nonextreme Black HolesJun 09 1998At low energy the near horizon geometry of nonextreme black holes in four dimensions exhibits an effective SL(2,R)_L x SL(2,R)_R symmetry. The parameters of the corresponding induced conformal field theory gives the correct expression for the black hole ... More
A String Model of Black Hole MicrostatesFeb 20 1997May 26 1997The statistical mechanics of black holes arbitrarily far from extremality is modeled by a gas of weakly interacting strings. As an effective low energy description of black holes the model provides a number of highly non-trivial consistency checks and ... More
Synthesis of Boolean Functions with Clausal AbstractionAug 27 2018Nov 19 2018Dependency quantified Boolean formulas (DQBF) is a logic admitting existential quantification over Boolean functions, which allows us to elegantly state synthesis problems in planning and verification. In this paper, we lift the clausal abstraction algorithm ... More
Anomalous effective charges and far IR optical absorption of Al$_2$Ru from first principlesAug 13 1996For the orthorhombic intermetallic semiconductor Al$_2$Ru, the bandstructure, valence charge density, zone center optical phonon frequencies, and Born effective charge and electronic dielectric tensors are calculated using variational density functional ... More
Temperature-dependent dielectric and piezoelectric response of ferroelectrics from first principlesApr 06 1998A method for the calculation of the temperature dependence of dielectric and piezoelectric responses, based on the use of a first-principles effective Hamiltonian, is described. Results are presented for the ferroelectric perovskite PbTiO3. While the ... More
Enhancement of piezoelectricity in a mixed ferroelectricDec 18 1997We use first-principles density-functional total energy and polarization calculations to calculate the piezoelectric tensor at zero temperature for both cubic and simple tetragonal ordered supercells of Pb_3GeTe_4. The largest piezoelectric coefficient ... More
Determination of ground-state and low-energy structures of perovskite superlattices from first principlesMar 12 2014In the development of first-principles high-throughput searches for materials with desirable functional properties, there is a clear need for an efficient method to determine the ground state and low-energy alternative structures of superlattices. A method ... More
Band gap and stability in the ternary intermetallic compounds NiSnM (M = Ti, Zr, Hf): A first principles studyOct 27 1994May 12 1995The structural stability and electronic properties of the ternary intermetallic compounds NiSnM (M = Ti, Zr, Hf) and the closely related Heusler compounds Ni$_2$SnM are discussed using the results of ab initio pseudopotential total energy and band-structure ... More
Epitaxially strained [001]-(PbTiO$_3$)$_1$(PbZrO$_3$)$_1$ superlattice and PbTiO$_3$ from first principlesDec 02 2003The effect of layer-by-layer heterostructuring and epitaxial strain on lattice instabilities and related ferroelectric properties is investigated from first principles for the [001]-(PbTiO$_3$)$_1$(PbZrO$_3$)$_1$ superlattice and pure PbTiO$_3$ on a cubic ... More
{High-density electron doping of SmNiO$_3$ from first principlesSep 08 2019Recent experimental work has realized a new insulating state of samarium nickelate (SmNiO$_3$), accessible in a reversible manner via high-density electron doping. To elucidate this behavior, we use the first-principles density functional theory (DFT) ... More
Polymorphism and metastability in NbN: Structural predictions from first principlesMay 17 1995We use ab initio pseudopotential total energy calculations with a plane wave basis set to investigate the structural energetics of various phases of polymorphic NbN. Particular attention is given to its recently discovered superconducting phase with a ... More
Fcc breathing instability in BaBiO_3 from first principlesJul 15 2005May 24 2006We present first-principles density-functional calculations using the local density approximation to investigate the structural instability of cubic perovskite BaBiO_3. This material might exhibit charge disproportionation and some evidence thereof has ... More
Coexistence of antiferrodistortive and ferroelectric distortions at the PbTiO$_3$ (001) surfaceOct 14 2004The c(2$\times$2) reconstruction of (001) PbTiO$_3$ surfaces is studied by means of first principles calculations for paraelectric (non-polar) and ferroelectric ([001] polarized) films. Analysis of the atomic displacements in the near-surface region shows ... More
Lattice instabilities of PbZrO3/PbTiO3 [1:1] superlattices from first principlesJan 31 2002Ab initio phonon calculations for the nonpolar reference structures of the (001), (110), and (111) PbZrO_3/PbTiO_3 [1:1] superlattices are presented. The unstable polar modes in the tetragonal (001) and (110) structures are confined in either the Ti- ... More
Ab Initio Study of the Structural Phase Transition in Cubic Pb_3GeTe_4Apr 15 1997In the substitutionally disordered narrow-gap semiconductor Pb_{1-x}Ge_xTe, a finite-temperature cubic-rhombohedral transition appears above a critical concentration $x \approx 0.005$. As a first step towards a first-principles investigation of this transition ... More
Coupled nonpolar-polar metal-insulator transition in 1:1 SrCrO$_3$/SrTiO$_3$ superlattices: A first-principles studyFeb 23 2015Using first principles calculations, we determined the epitaxial-strain dependence of the ground state of the 1:1 SrCrO$_3$/SrTiO$_3$ superlattice. The superlattice layering leads to significant changes in the electronic states near the Fermi level, derived ... More
Configuration dependence of physical properties of a ferroelectric solid solutionApr 08 1998In this article, we motivate the detailed comparison of the physical properties of individual configurations of a ferroelectric solid solution as a means toward developing first principles models for these systems. We compare energies, dielectric constants ... More
Ab initio statistical mechanics of the ferroelectric phase transition in PbTiO3Aug 01 1996An effective Hamiltonian for the ferroelectric transition in PbTiO3 is constructed from first-principles density-functional-theory total-energy and linear-response calculations through the use of a localized, symmetrized basis set of ``lattice Wannier ... More
Magnetic-induced phonon anisotropy in ZnCr$_2$O$_4$ from first principlesFeb 21 2006We have studied the influence of magnetic order on the optical phonons of the geometrically frustrated spinel ZnCr$_2$O$_4$ from first-principles. By mapping the first-principles phonon calculations onto a Heisenberg-like model, we developed a method ... More
First-principles study of epitaxial strain in perovskitesJun 29 2005Using an extension of a first-principles method developed by King-Smith and Vanderbilt [Phys. Rev. B {\bf 49}, 5828 (1994)], we investigate the effects of in-plane epitaxial strain on the ground-state structure and polarization of eight perovskite oxides: ... More
Integration of first-principles methods and crystallographic database searches for new ferroelectrics: Strategies and explorationsJan 13 2012Jun 20 2012In this concept paper, the development of strategies for the integration of first-principles methods with crystallographic database mining for the discovery and design of novel ferroelectric materials is discussed, drawing on the results and experience ... More
Epitaxial-strain-induced multiferroicity in SrMnO$_{3}$ from first principlesOct 28 2009Dec 21 2009First-principles density-functional calculations reveal a large spin-phonon coupling in cubic SrMnO$_{3}$, with ferromagnetic ordering producing a polar instability. Through combination of this coupling with the strain-polarization coupling characteristic ... More
Anomalous enhancement of tetragonality in PbTiO3 induced by negative pressureJun 09 2003Using a first-principles approach based on density-functional theory, we find that a large tetragonal strain can be induced in PbTiO3 by application of a negative hydrostatic pressure. The structural parameters and the dielectric and dynamical properties ... More
Magnetostructural Effect in the Multiferroic BiFeO3-BiMnO3 Checkerboard from First PrinciplesJun 17 2009Using first principles calculations, we present a magnetostructural effect in the BiFeO3-BiMnO3 nanocheckerboard that is not found in either bulk parent compound or in BiFeO3-BiMnO3 superlattices. We also demonstrate that the atomic-scale checkerboard ... More
Theory of polarization enhancement in epitaxial BaTiO$_3$/SrTiO$_3$ superlatticesNov 19 2002The spontaneous polarization of epitaxial BaTiO$_3$/SrTiO$_3$ superlattices is studied as a function of composition using first-principles density functional theory within the local density approximation. With the in-plane lattice parameter fixed to that ... More
Coupled magnetic-ferroelectric metal-insulator transitions in epitaxially-strained SrCoO$_{3}$ from first principlesApr 14 2011First-principles calculations of the epitaxial-strain phase diagram of perovskite SrCoO$_{3}$ are presented. Through combination of the large spin-phonon coupling with polarization-strain coupling and coupling of the band gap to the polar distortion, ... More
Localized Basis for Effective Lattice Hamiltonians: Lattice Wannier FunctionsNov 17 1994Aug 27 1995A systematic method is presented for constructing effective Hamiltonians for general phonon-related structural transitions. The key feature is the application of group theoretical methods to identify the subspace in which the effective Hamiltonian acts ... More
A Foundational View on Integration ProblemsMay 13 2011The integration of reasoning and computation services across system and language boundaries is a challenging problem of computer science. In this paper, we use integration for the scenario where we have two systems that we integrate by moving problems ... More
Surface polarization and edge chargesMay 01 2015The term "surface polarization" is introduced to describe the in-plane polarization existing at the surface of an insulating crystal when the in-plane surface inversion symmetry is broken. Here, the surface polarization is formulated in terms of a Berry ... More
BICEP2 and the Central Charge of Holographic InflationMay 07 2014Aug 01 2014Holographic inflation posits that the inflationary deSitter era of our universe is approximately described by a dual three-dimensional Euclidean CFT living on the spatial slice at the end of inflation. We point out that the BICEP2 results determine the ... More
How do Markov approximations compare with other methods for large spatial data sets?Jun 10 2011Nov 04 2011The Mat\'ern covariance function is a popular choice for modeling dependence in spatial environmental data. Standard Mat\'ern covariance models are, however, often computationally infeasible for large data sets. In this work, recent results for Markov ... More
A new ANEW: Evaluation of a word list for sentiment analysis in microblogsMar 15 2011Sentiment analysis of microblogs such as Twitter has recently gained a fair amount of attention. One of the simplest sentiment analysis approaches compares the words of a posting against a labeled word list, where each word has been scored for valence, ... More
Proton-Proton Scattering Lengths from Effective Field TheoryNov 20 1998Mar 27 1999Using a recently developed effective field theory for the interactions of nucleons at non-relativistic energies, we calculate the Coulomb corrections to proton-proton scattering. Including the dimension-eight derivative interaction in PDS regularization ... More
Non-Relativistic Pion Interactions and the Pionium LifetimeMay 18 1998Jun 08 1998We construct an effective Lagrangian for interacting pions with non-relativistic energies. The coupling constants can be expressed in terms of the different scattering lengths and slopes. When used in the calculation of the pionium decay rate, the scattering ... More
Detection, Measurement and Gravitational RadiationSep 24 1992Here I examine how to determine the sensitivity of the LIGO, VIRGO, and LAGOS gravitational wave detectors to sources of gravitational radiation by considering the process by which data are analyzed in a noisy detector. By constructing the probability ... More
The Laser Interferometer Gravitational-wave Observatory Scientific Data ArchiveMar 30 1999LIGO --- The Laser Interferometer Gravitational-Wave Observatory --- is one of several large projects being undertaken in the United States, Europe and Japan to detect gravitational radiation. The novelty and precision of these instruments is such that ... More
Greybody Factors for Black Holes in Four Dimensions: Particles with SpinDec 11 1997We compute the emission spectrum of minimally coupled particles with spin that are Hawking radiated from four dimensional black holes in string theory. For a range of the black hole parameters the result has a product structure that may be interpreted ... More
Defining a Research Environment: LIGO and the Gravitational Physics Research CommunityFeb 01 1996Feb 07 1996The LIGO Research Community (LRC) is an independent organization of researchers interested in the scientific opportunities created by the construction and operation of the Laser Interferometer Gravitational-wave Observatory (LIGO). Membership is open ... More
Observational constraints on the neutron star mass distributionSep 22 1994Radio observations of neutron star binary pulsar systems have constrained strongly the masses of eight neutron stars. Assuming neutron star masses are uniformly distributed between lower and upper bounds $m_l$ and $m_u$, the observations determine with ... More
Calculating probabilistic excursion sets and related quantities using excursionsDec 13 2016Aug 14 2017The R software package excursions contains methods for calculating probabilistic excursion sets, contour credible regions, and simultaneous confidence bands for latent Gaussian stochastic processes and fields. It also contains methods for uncertainty ... More
Deep Visual Foresight for Planning Robot MotionOct 03 2016Mar 13 2017A key challenge in scaling up robot learning to many skills and environments is removing the need for human supervision, so that robots can collect their own data and improve their own performance without being limited by the cost of requesting human ... More
Soft tetragonal distortions in ferromagnetic Ni_2MnGa and related materials from first principlesSep 26 2000A detailed examination of the energy landscape, density of states and magnetic moment of tetragonally distorted ferromagnetic Ni_2MnGa was performed using first-principles local-spin-density (LSD) pseudopotential calculations, varying V as well as c/a. ... More
Structural Stability of Vacancy-ordered Yb2.75C60Sep 18 1997The fcc-based structure of Yb2.75C60 is unique among metal-doped fullerene compounds, exhibiting long-range-ordered vacancies, significantly off-centered divalent Yb cations, and distorted, crystallographically inequivalent, orientationally ordered C60 ... More
Ferroelectric Phase Transitions from First PrinciplesMay 18 1995An effective Hamiltonian for the ferroelectric transition in $PbTiO_3$ is constructed from first-principles density-functional-theory total-energy and linear-response calculations through the use of a localized, symmetrized basis set of ``lattice Wannier ... More
Phase transitions in BaTiO$_3$ from first principlesJun 10 1994We develop a first-principles scheme to study ferroelectric phase transitions for perovskite compounds. We obtain an effective Hamiltonian which is fully specified by first-principles ultra-soft pseudopotential calculations. This approach is applied to ... More
Canonical Selection of ColimitsMay 25 2017Colimits are a powerful tool for the combination of objects in a category. In the context of modeling and specification, they are used in the institution-independent semantics (1) of instantiations of parameterised specifications (e.g. in the specification ... More
Towards MKM in the Large: Modular Representation and Scalable Software ArchitectureMay 28 2010May 31 2010MKM has been defined as the quest for technologies to manage mathematical knowledge. MKM "in the small" is well-studied, so the real problem is to scale up to large, highly interconnected corpora: "MKM in the large". We contend that advances in two areas ... More
Large spin-phonon coupling and magnetically-induced phonon anisotropy in Sr$M$O$_3$ perovskites ($M$=V,Cr,Mn,Fe,Co)Jul 22 2011First-principles calculations reveal large zone-center spin-phonon coupling and magnetically-driven phonon anisotropy in cubic perovskites Sr$M$O$_3$ ($M$=V,Cr,Mn,Fe,Co). In particular, the frequency and splitting of the polar Slater mode is found to ... More
Magnetic and electric phase control in epitaxial EuTiO$_3$ from first principlesJun 26 2006Jul 26 2006We propose a design strategy - based on the coupling of spins, optical phonons, and strain - for systems in which magnetic (electric) phase control can be achieved by an applied electric (magnetic) field. Using first-principles density-functional theory ... More
Predicting polarization enhancement in multicomponent ferroelectric superlatticesDec 15 2005Ab initio calculations are utilized as an input to develop a simple model of polarization in epitaxial short-period CaTiO3/SrTiO3/BaTiO3 superlattices grown on a SrTiO3 substrate. The model is then combined with a genetic algorithm technique to optimize ... More
Multiferroic BiFeO3-BiMnO3 Nanocheckerboard From First PrinciplesJun 23 2010We present a first principles study of an unusual heterostructure, an atomic-scale checkerboard of BiFeO3-BiMnO3, and compare its properties to the two bulk constituent materials, BiFeO3 and BiMnO3. The "nanocheckerboard" is found to have a multiferroic ... More
First-principles theory of ferroelectric phase transitions for perovskites: The case of BaTiO3Feb 13 1995We carry out a completely first-principles study of the ferroelectric phase transitions in BaTiO$_3$. Our approach takes advantage of two features of these transitions: the structural changes are small, and only low-energy distortions are important. Based ... More
Negative piezoelectric response of van der Waals layered bismuth tellurohalidesJun 17 2019The polarization and piezoelectric response of the BiTe$X$ ($X$=Cl, Br, and I) layered tellurohalides are computed from first principles. The results confirm a mixed ionic-covalent character of the bonding, and demonstrate that the internal structure ... More
Enhancing piezoelectricity through polarization-strain coupling in ferroelectric superlatticesJan 07 2009Jan 09 2009Short period ferroelectric/ferroelectric BaTiO3 (BTO)/PbTiO3 (PTO) superlattices are studied using density functional theory. Contrary to the trends in paraelectric/ferroelectric superlattices the polarization remains nearly constant for PTO concentrations ... More
Polar phonons and intrinsic dielectric response of the ferromagnetic insulating spinel CdCr$_2$S$_4$ from first principlesAug 04 2005We have studied the dielectric properties of the ferromagnetic spinel CdCr$_2$S$_4$ from first principles. Zone-center phonons and Born effective charges were calculated by frozen-phonon and Berry phase techniques within LSDA+U. We find that all infrared-active ... More
First Principles Investigation of Ferromagnetism and Ferroelectricity in Bismuth ManganiteSep 21 1998We present results of local spin density approximation (LSDA) pseudopotential calculations for the perovskite structure oxide, bismuth manganite (BiMnO3). The origin of the differences between bismuth manganite and other perovskite manganites is determined ... More
Antiferroelectricity and ferroelectricity in epitaxially strained PbZrO3 from first principlesJul 29 2013May 14 2014Density functional calculations are performed to study the effect of epitaxial strain on PbZrO3. We find a remarkably small energy difference between the epitaxially strained polar R3c and nonpolar Pbam structures over the full range of experimentally ... More
Modelling Thickness-Dependence of Ferroelectric Thin Film PropertiesApr 20 2007Oct 07 2007We present a segregrated strain model that describes the thickness-dependent dielectric properties of ferroelectric films. Using a phenomenological Landau approach, we present results for two specific materials, making comparison with experiment and with ... More
Excursion and contour uncertainty regions for latent Gaussian modelsNov 16 2012An interesting statistical problem is to find regions where some studied process exceeds a certain level. Estimating such regions so that the probability for exceeding the level in the entire set is equal to some predefined value is a difficult problem ... More
Partition Sums and Entropy Bounds in Weakly Coupled CFTSep 29 2000We use the partition functions on S^1 x S^n of various conformal field theories in four and six dimensions in the limit of vanishing coupling to study the high temperature thermodynamics. Certain modular properties exhibited by the partition functions ... More
U(1) Charges and Moduli in the D1-D5 SystemMay 10 1999Jun 18 1999The decoupling limit of the D1-D5 system compactified on T^4\times S^1 has a rich spectrum of U(1) charged excitations. Even though these states are not BPS in the limit, BPS considerations determine the mass and the semiclassical entropy for a given ... More
Extremal Branes as Elementary ParticlesOct 10 1996Mar 06 1997The supersymmetric p-branes of Type II string theory can be interpreted after compactification as extremal black holes with zero entropy and infinite temperature. We show how the p-branes avoid this apparent, catastrophic instability by developing an ... More
Classical Hair in String Theory II: Explicit CalculationsSep 10 1996After emphasizing the importance of obtaining a space-time understanding of black hole entropy, we further elaborate our program to identify the degrees of freedom of black holes with classical space-time degrees of freedom. The Cveti\v{c}-Youm dyonic ... More
Binary inspiral, gravitational radiation, and cosmologyJan 31 1996Observations of binary inspiral in a single interferometric gravitational wave detector can be cataloged according to signal-to-noise ratio $\rho$ and chirp mass $\cal M$. The distribution of events in a catalog composed of observations with $\rho$ greater ... More
Internal Structure of Black HolesNov 09 1995We present a number of qualitative arguments which strongly suggest that extremal dyonic black holes in the 4--dimensional low energy, classical field theory limit of toroidally compactified heterotic string theory represent largely degenerate classes ... More
Prediction with Restricted Resources and Finite AutomataDec 10 2008We obtain an index of the complexity of a random sequence by allowing the role of the measure in classical probability theory to be played by a function we call the generating mechanism. Typically, this generating mechanism will be a finite automata. ... More
Scalar Field Fluctuations between Parallel PlatesAug 26 2004Sep 15 2004Quantum fluctuations of a scalar field and its derivatives are calculated when the field is confined between two parallel plates satisfying Dirichlet or Neumann boundary conditions. After regulation these fluctuations diverge in general when one approaches ... More
Inflation and de Sitter HolographyJul 02 2003We develop the relation between de Sitter holography and inflation in detail, with particular attention to cosmic density perturbations. We set up the Hamilton-Jacobi formalism to present a systematic treatment of the logarithmic corrections to a scale ... More
Issues in gravitational wave data analysisSep 29 1997Data analysis is the application of probability and statistics to draw inference from observation. Is a signal present or absent? Is the source an inspiraling binary system or a supernova? At what point in the sky is the radiation incident from? In these ... More
Vertex theorems for capillary drops on support planesJul 07 1997We consider a capillary drop that contacts several planar bounding walls so as to produce singularities (vertices) in the boundary of its free surface. It is shown under various conditions that when the number of vertices is less than or equal to three, ... More
What is the Regularized Casimir Vacuum Energy Density?Jan 17 1997The regularized total Casimir energy in spacetimes with boundaries is not in general equal to the integral of the regularized energy density. This paradoxical phenomenon is most transparently analyzed in the simple example of a massless scalar field in ... More
Active One-shot LearningFeb 21 2017Recent advances in one-shot learning have produced models that can learn from a handful of labeled examples, for passive classification and regression tasks. This paper combines reinforcement learning with one-shot learning, allowing the model to decide, ... More
On the Capillarity Equation in Two DimensionsMar 23 2016We study the capillarity equation from the global point of view of behavior of its solutions without explicit regard to boundary conditions. We show its solutions to be constrained in ways, that have till now not been characterized in literature known ... More
A Sufficient Statistics Construction of Bayesian Nonparametric Exponential Family Conjugate ModelsJan 10 2016Conjugate pairs of distributions over infinite dimensional spaces are prominent in statistical learning theory, particularly due to the widespread adoption of Bayesian nonparametric methodologies for a host of models and applications. Much of the existing ... More
Wembedder: Wikidata entity embedding web serviceOct 11 2017I present a web service for querying an embedding of entities in the Wikidata knowledge graph. The embedding is trained on the Wikidata dump using Gensim's Word2Vec implementation and a simple graph walk. A REST API is implemented. Together with the Wikidata ... More
Divergences and Boundary Modes in N=8 SupergravityAug 14 2015We reconsider the one loop divergence of ${\cal N}=8$ supergravity in four dimensions. We compute the finite effective potential of ${\cal N}=8$ anti-deSitter supergravity and interpret it as logarithmic running of the cosmological constant. We find that ... More
Adding Data to CurryAug 28 2019Functional logic languages can solve equations over user-defined data and functions. Thus, the definition of an appropriate meaning of equality has a long history in these languages, ranging from reflexive equality in early equational logic languages ... More
Deep Visual Foresight for Planning Robot MotionOct 03 2016A key challenge in scaling up robot learning to many skills and environments is removing the need for human supervision, so that robots can collect their own data and improve their own performance without being limited by the cost of requesting human ... More
A Finite Measure for the Initial Conditions of InflationDec 17 2018May 23 2019We investigate whether inflation requires finely tuned initial conditions in order to explain the degree of flatness and homogeneity observed in the Universe. We achieve this by using the Eisenhart lift, which can be used to write any scalar field theory ... More
Poisson equations, higher derivative automorphic forms and string parameter limitsJan 18 2014Apr 03 2014This paper considers the higher derivative terms in the effective action of type II string theory and in particular the behaviour of the automorphic forms they contain in all the different possible limits of the string parameters. The automorphic forms ... More