Results for "Erik Sy"

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Surfing the Web quicker than QUIC via a shared Address ValidationMar 22 2019QUIC is a performance-optimized secure transport protocol and a building block of the upcoming HTTP/3 standard. To protect against denial-of-service attacks, QUIC servers need to validate the IP addresses claimed by their clients. So far, the QUIC protocol ... More
Coding Without Fine StructureSep 01 1995We present a proof of Jensen's Coding Theorem (assumong -0#) which quotes the covering lemma, but otherwise makes no appeal to fine structure theory. The key idea is to use a modified definition of the coding at limit cardinals, using "coding delays". ... More
QUICker connection establishment with out-of-band validation tokensApr 12 2019May 03 2019QUIC is a secure transport protocol that improves the performance of HTTPS. An initial QUIC handshake that enforces a strict validation of the client's source address requires two round-trips. In this work, we extend QUIC's address validation mechanism ... More
Tracking Users across the Web via TLS Session ResumptionOct 16 2018User tracking on the Internet can come in various forms, e.g., via cookies or by fingerprinting web browsers. A technique that got less attention so far is user tracking based on TLS and specifically based on the TLS session resumption mechanism. To the ... More
Enhanced Performance for the encrypted Web through TLS Resumption across HostnamesFeb 07 2019TLS can resume previous connections via abbreviated resumption handshakes that significantly decrease the delay and save expensive cryptographic operations. For that, cryptographic TLS state from previous connections is reused. TLS version 1.3 recommends ... More
QUICker connection establishment with out-of-band validation tokensApr 12 2019QUIC is a secure transport protocol and aims to improve the performance of HTTPS traffic. It is a design goal of QUIC to reduce the delay overhead of its connection establishment. However, an initial handshake enforcing strict validation of the client's ... More
Enhanced Performance and Privacy for TLS over TCP Fast OpenMay 09 2019Small TCP flows make up the majority of web flows. For them, the TCP three-way handshake represents a significant delay overhead. The TCP Fast Open (TFO) protocol provides zero round-trip time (0-RTT) handshakes for subsequent TCP connections to the same ... More
On the complexity of classes of uncountable structures: trees on $\aleph_1$Jun 03 2019We analyse the complexity of the class of (special) Aronszajn, Suslin and Kurepa trees in the projective hierarchy of the higher Baire-space $\omega_1^{\omega_1}$. First, we will show that none of these classes have the Baire property (unless they are ... More
Almost sure global well-posedness for the septic Schrödinger equation on $\Bbb T^3$May 09 2019We consider the septic Schr\"odinger equation on the three-dimensional torus. We construct a non-trivial measure supported on the Sobolev space $H^2$ and show that the equation is globally well-posed on the support of this measure. Moreover, the measure ... More
Definable maximal cofinitary groups of intermediate sizeApr 11 2019Using almost disjoint coding, we show that for each $1<M<N<\omega$ consistently $\mathfrak{d}=\mathfrak{a}_g=\aleph_M<\mathfrak{c}=\aleph_N$, where $\mathfrak{a}_g=\aleph_M$ is witnessed by a $\Pi^1_2$ maximal cofinitary group.
Residual symmetries and Bäcklund transformationsAug 05 2013It is proved that for a given truncated Painlev\'e expansion of an arbitrary nonlinear Painlev\'e integrable system, the residue with respect to the singularity manifold is a nonlocal symmetry. The residual symmetries can be localized to Lie point symmetries ... More
Monte Carlo simulation of spin models with long-range interactionsJun 15 1999An efficient Monte Carlo algorithm for the simulation of spin models with long-range interactions is discussed. Its central feature is that the number of operations required to flip a spin is independent of the number of interactions between this spin ... More
Attractors and the Holomorphic AnomalyDec 14 2004Motivated by the recently proposed connection between N=2 BPS black holes and topological strings, I study the attractor equations and their interplay with the holomorphic anomaly equation. The topological string partition function is interpreted as a ... More
Entanglement-induced geometric phase of quantum statesMar 18 2008Mar 09 2010The concept of relative state is used to introduce geometric phases that originate from correlations in states of composite quantum systems. In particular, we identify an entanglement-induced geometric phase in terms of a weighted average of geometric ... More
On the alleged nonlocal and topological nature of the molecular Aharonov-Bohm effectOct 31 2003Sep 09 2004The nonlocal and topological nature of the molecular Aharonov-Bohm (MAB) effect is examined for real electronic Hamiltonians. A notion of preferred gauge for MAB is suggested. The MAB effect in the linear + quadratic $E\otimes \epsilon$ Jahn-Teller system ... More
More on functional and quantitative versions of the isoperimetric inequalitySep 14 2016This paper deals with the famous isoperimetric inequality. In a first part, we give some new functional form of the isoperimetric inequality, and in a second part, we give a quantitative form with a remainder term involving Wasserstein distance of the ... More
On determinacy/indeterminacy of Moment ProblemsApr 21 2016This paper treat determinacy of strong moment problems in part I and indeterminacy of strong moment problems in part II. This paper is a summary of the following papers: [1] Ald\'en. E., Determinacy of Strong Moment Problems. [2] On Indeterminacy of Strong ... More
A Simple Proof of the Uniqueness of the Einstein Field Equation in All DimensionsJan 12 2016The standard argument for the uniqueness of the Einstein field equation is based on Lovelock's Theorem, the relevant statement of which is restricted to four dimensions. I prove a theorem similar to Lovelock's, with a physically modified assumption: that ... More
The parity theorem for multiple polylogarithmsDec 14 2015Oct 03 2016We generalize the well-known parity theorem for multiple zeta values (MZV) to functional equations of multiple polylogarithms (MPL). This reproves the parity theorem for MZV with an additional integrality statement, and also provides parity theorems for ... More
Feynman integrals and hyperlogarithmsJun 24 2015We study Feynman integrals in the representation with Schwinger parameters and derive recursive integral formulas for massless 3- and 4-point functions. Properties of analytic (including dimensional) regularization are summarized and we prove that in ... More
Error estimates for stabilized finite element methods applied to ill-posed problemsJun 17 2014We propose an analysis for the stabilized finite element methods proposed in, E. Burman, Stabilized finite element methods for nonsymmetric, noncoercive, and ill-posed problems. Part I: Elliptic equations. SIAM J. Sci. Comput., 35(6) 2013, valid in the ... More
On T-duality transformations for the three-sphereAug 07 2014Mar 25 2015We study collective T-duality transformations along one, two and three directions of isometry for the three-sphere with H-flux. Our aim is to obtain new non-geometric backgrounds along lines similar to the example of the three-torus. However, the resulting ... More
Enumeration of monochromatic three term arithmetic progressions in two-colorings of any finite groupAug 05 2014Nov 10 2014There are many extremely challenging problems about existence of monochromatic arithmetic progressions in colorings of groups. Many theorems hold only for abelian groups as results on non-abelian groups are often much more difficult to obtain. In this ... More
Anisotropic diffusive transport: connecting microscopic scattering and macroscopic transport propertiesNov 14 2013Aug 12 2014This work concerns the modeling of radiative transfer in anisotropic turbid media using diffusion theory. A theory for the relationship between microscopic scattering properties (i.e., an arbitrary differential scattering cross-section) and the macroscopic ... More
T-duality revisitedOct 15 2013Jan 29 2014We revisit the transformation rules of the metric and Kalb-Ramond field under T-duality, and express the corresponding relations in terms of the metric G and the field strength H=dB. In the course of the derivation, we find an explanation for potential ... More
Asymptotically Safe Gravitons in Electroweak Precision PhysicsDec 06 2010Nov 11 2011Asymptotic safety offers a field theory based UV completion to gravity. For low Planck scales, gravitational effects on low-energy precision observables cannot be neglected. We compute the contribution to the rho parameter from asymptotically safe gravitons ... More
Spin-orbit interactions in a helical Luttinger liquid with a Kondo impurityMar 14 2013Jun 17 2013The combined effect of Rashba and Dresselhaus spin-orbit interactions on the physics of a helical Luttinger liquid coupled to a Kondo impurity is studied. A Rashba coupling can potentially destroy the Kondo singlet formation in certain parameter regimes ... More
Stationary probability of the identity for the TASEP on a ringDec 27 2012Consider the following Markov chain on permutations of length $n$. At each time step we choose a random position. If the letter at that position is smaller than the letter immediately to the left (cyclically) then these letters swap positions. Otherwise ... More
Holographic entanglement entropy: near horizon geometry and disconnected regionsOct 31 2010We study the finite term of the holographic entanglement entropy for the charged black hole in AdS(d+2) and other examples of black holes when the spatial region in the boundary theory is given by one or two parallel strips. For one large strip it scales ... More
A `superoutburst' in XTE J1118+480Feb 05 2001Feb 14 2001I propose that the properties of the two outbursts observed in the X-ray transient XTE J1118+480 in 2000 are akin to superoutbursts of SU UMa stars. In these systems a `normal' outburst immediately precedes a 5-10 times longer (`super')outburst. The optical ... More
A0620-00 revisited: a black-hole transient case-studyMay 05 1998For the first time we have performed a detailed study of the X-ray, optical and infra-red light curves of the 1975/1976 outburst of the famous black-hole transient A0620-00 (Nova Mon 1975, V616 Mon). During the various stages of its outburst the X-rays ... More
Del Pezzo Surfaces in Weighted Projective SpacesJan 23 2013Apr 13 2016We study singular del Pezzo surfaces that are quasi-smooth and well-formed weighted hypersurfaces. We give an algorithm how to classify all of them.
Review of "Garden of integrals"Feb 06 2008This is a review of the book "Garden of integrals" by Frank Burk.
Isotopes of Hurwitz algebrasDec 08 2010Sep 22 2015We study the class of all algebras that are isotopic to a Hurwitz algebra. Isomorphism classes of such algebras are shown to correspond to orbits of a certain group action. A complete, geometrically intuitive description of the category of isotopes of ... More
The $\infty$-harmonic potential is not always an $\infty$-eigenfunctionOct 11 2012Oct 26 2012In this note we prove that there is a convex domain for which the $\infty$-harmonic potential is not a first $\infty$-eigenfunction.
Applications of spectral theory to special functionsDec 21 2016Lecture notes for one of the courses at the OPSFA Summerschool 6, July 11-15, 2016. All the results in these notes have appeared in the literature. Many special functions are eigenfunctions to explicit operators, such as difference and differential operators, ... More
Self-Correcting Models for Model-Based Reinforcement LearningDec 19 2016Jul 26 2017When an agent cannot represent a perfectly accurate model of its environment's dynamics, model-based reinforcement learning (MBRL) can fail catastrophically. Planning involves composing the predictions of the model; when flawed predictions are composed, ... More
Framework Confirmation by Newtonian AbductionApr 20 2018The analysis of theory-confirmation generally takes the form: show that a theory in conjunction with physical data and auxiliary hypotheses yield a prediction about phenomena; verify the prediction; provide a quantitative measure of the degree of theory-confirmation ... More
Symmetric Functions and CapsAug 21 2008Given a finite subset S in F_p^d, let a(S) be the number of distinct r-tuples (x_1,...,x_r) in S such that x_1+...+x_r = 0. We consider the "moments" F(m,n) = sum_|S|=n a(S)^m. Specifically, we present an explicit formula for F(m,n) as a product of two ... More
The $h$-vectors of 1-dimensional Matroid Complexes and a Conjecture of StanleyMar 20 2009A matroid complex is a pure complex such that every restriction is again pure. It is a long-standing open problem to classify all possible $h$-vectors of such complexes. In the case when the complex has dimension 1 we completely resolve this question. ... More
Selected astrometric cataloguesJun 25 2017Jul 09 2017A selection of astrometric catalogues are presented in three tables for respectively positions, proper motions and trigonometric parallaxes. The tables contain characteristics of each catalogue showing the evolution in optical astrometry, in fact the ... More
GIER: A Danish computer from 1961 with a role in the modern revolution of astronomyApr 19 2017A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. ... More
Resolving observable features of galaxy cluster merger 'El Gordo' using idealized cluster models in SPH simulationsAug 18 2017Sep 02 2017The merger scenario of two galaxy subclusters to form the massive galaxy cluster 'El Gordo' is investigated using smoothed particle hydrodynamics (SPH) simulations. Idealized cluster models are used to initialize the states of both subclusters prior to ... More
One-point functions in $β$-deformed N = 4 SYM with defectApr 25 2018We generalize earlier results on one-point functions in N = 4 SYM with a co-dimension one defect, dual to the D3-D5-brane setup in type IIB string theory on AdS5xS5, to a similar setup in the $\beta$-deformed version of the theory. The treelevel vacuum ... More
Fourier transform inversion using an elementary differential equation and a contour integralAug 13 2018Let $f$ be a function on the real line. The Fourier transform inversion theorem is proved under the assumption that $f$ is absolutely continuous such that $f$ and $f'$ are Lebesgue integrable. A function $g$ is defined by $f'(t)-iwf(t)=g(t)$. This differential ... More
Plasma Wakefield Linear Colliders - Opportunities and ChallengesMay 06 2019A linear electron-positron collider operating at TeV scale energies will provide high precision measurements and allow, for example, precision studies of the Higgs boson as well as searches for physics beyond the standard model. A future linear collider ... More
Vector product algebrasOct 30 2008Vector products can be defined on spaces of dimensions 0, 1, 3 and 7 only, and their isomorphism types are determined entirely by their adherent symmetric bilinear forms. We present a short and elementary proof for this classical result.
Higher order corrected trapezoidal rules in Lebesgue and Alexiewicz spacesApr 28 2016If $f\!:\![a,b]\to\R$ such that $f^{(n)}$ is integrable then integration by parts gives the formula \begin{align*} &\intab f(x)\,dx = &\frac{(-1)^n}{n!}\sum_{k=0}^{n-1}(-1)^{n-k-1}\left[ \phi_n^{(n-k-1)}(a)f^{(k)}(a)- \phi_n^{(n-k-1)}(b)f^{(k)}(b)\right] ... More
The one-dimensional heat equation in the Alexiewicz normJan 18 2015A distribution on the real line has a continuous primitive integral if it is the distributional derivative of a function that is continuous on the extended real line. The space of distributions integrable in this sense is a Banach space that includes ... More
The distributional Denjoy integralJun 21 2006Dec 07 2007Let $f$ be a distribution (generalised function) on the real line. If there is a continuous function $F$ with real limits at infinity such that $F'=f$ (distributional derivative) then the distributional integral of $f$ is defined as $\int_{-\infty}^\infty ... More
Bond Market Completeness and Attainable Contingent ClaimsFeb 23 2004Mar 03 2005A general class, introduced in [Ekeland et al. 2003], of continuous time bond markets driven by a standard cylindrical Brownian motion $\wienerq{}{}$ in $\ell^{2},$ is considered. We prove that there always exist non-hedgeable random variables in the ... More
Interferometry from Space: A Great DreamAug 20 2014During some thirty years, 1980-2010, technical studies of optical interferometry from instruments in space were pursued as promising for higher spatial resolution and for higher astrometric accuracy. Nulling interferometry was studied for both high spatial ... More
Absolute astrometry in the next 50 yearsAug 10 2014Aug 03 2017With Gaia in orbit since December 2013 it is time to look at the future of fundamental astrometry and a time frame of 50 years is needed in this matter. A space mission with Gaia-like astrometric performance is required, but not necessarily a Gaia-like ... More
Calculating the Tate local pairing for any odd prime numberOct 04 2016Fisher and Newton have given an explicit description of the Tate local pairing associated with the 3-torsion of an elliptic curve. The present paper summarizes the work from the author's master's thesis and gives an explicit formula for any odd prime ... More
Decompositions of Schur block productsNov 08 2018Feb 17 2019Given two m x n matrices A = (a_{ij}) and B=(b_{ij}) with entries in B(H), the Schur block product is the m x n matrix A \square B := (a_{ij}b_{ij}). There exists an m x n contraction matrix S = (s_{ij}), such that A \square B = diag(AA*)^(1/2) S diag(B*B)^(1/2). ... More
On the complete boundedness of the Schur block productDec 14 2017Nov 08 2018We give a Stinespring representation of the Schur block product, say (*), on pairs of square matrices with entries in a C*-algebra as a completely bounded bilinear operator of the form: A:=(a_{ij}), B:= (b_{ij}): A (*) B := (a_{ij}b_{ij}) = V* pi(A) F ... More
A projection formula for the ind-GrassmannianMar 22 2013Jul 29 2013Let $X = \bigcup_k X_k$ be the ind-Grassmannian of codimension $n$ subspaces of an infinite-dimensional torus representation. If $\cE$ is a bundle on $X$, we expect that $\sum_j (-1)^j \Lambda^j(\cE)$ represents the $K$-theoretic fundamental class $[\cO_Y]$ ... More
Trigonometry of The Gold-BugMay 31 2012The classic Edgar Allan Poe story The Gold-Bug involves digging for pirate treasure. Locating the digging sites requires some simple trigonometry.
Addition formula for 2-parameter family of Askey-Wilson polynomialsDec 07 1994For a two parameter family of Askey-Wilson polynomials, that can be regarded as basic analogues of the Legendre polynomials, an addition formula is derived. The addition formula is a two-parameter extension of Koornwinder's addition formula for the little ... More
Enhancing Tc in field-doped Fullerenes by applying uniaxial stressDec 18 2001Capitalizing on the two-dimensional nature of superconductivity in field-effect doped C60, we show that it should be possible to increase the transition temperature Tc by applying uniaxial stress perpendicular to the gate electrode. This method not only ... More
Supershells in Metal Clusters: Self-Consistent Calculations and their Semiclassical InterpretationJun 05 1996To understand the electronic shell- and supershell-structure in large metal clusters we have performed self-consistent calculations in the homogeneous, spherical jellium model for a variety of different materials. A scaling analysis of the results reveals ... More
On the 3n+l Quantum Number in the Cluster ProblemJun 08 1996It has recently been suggested that an exactly solvable problem characterized by a new quantum number may underlie the electronic shell structure observed in the mass spectra of medium-sized sodium clusters. We investigate whether the conjectured quantum ... More
A global view of quantum computation with noisy componentsJun 30 2016The operation of a quantum computer is considered as a general quantum operation on a mixed state on many qubits followed by a measurement. The general quantum operation is further represented as a Feynman-Vernon double path integral over the histories ... More
On RG-flow and the Cosmological ConstantDec 07 1999Dec 13 1999The AdS/CFT correspondence implies that the effective action of certain strongly coupled large $N$ gauge theories satisfy the Hamilton-Jacobi equation of 5d gravity. Using an analogy with the relativistic point particle, I construct a low energy effective ... More
Global Aspects of Electric-Magnetic DualityJun 01 1995Jun 06 1995We show that the partition function of free Maxwell theory on a generic Euclidean four-manifold transforms in a non-trivial way under electric-magnetic duality. The classical part of the partition sum can be mapped onto the genus-one partition function ... More
Ordinary differential equations with only entire solutionsJun 06 1997We prove necessary and sufficient conditions for a system $\dot z_i=z_ip_i(z)$ ($p_i$ a polynomial) to have only entire analytic functions as solutions.
Grand Unification with Higher Rank Product GroupsJan 27 2005Various ideas support the notion that the GUT gauge group might be a semi-simple direct-product group such as $SU(5) \times SU(5)$. The doublet-triplet splitting problem can be solved with a direct product group. String theory suggests that the GUT scale ... More
A quantum cloning bound and application to quantum key distributionMar 20 2013Aug 14 2013We introduce a quantum cloning bound which we apply to a straightforward and relatively direct security proof of the prepare-and-measure Bennett-Brassard 1984 (BB84) quantum key distribution (QKD) protocol against collective attacks. The approach we propose ... More
On geometric phases for quantum trajectoriesAug 30 2006A sequence of completely positive maps can be decomposed into quantum trajectories. The geometric phase or holonomy of such a trajectory is delineated. For nonpure initial states, it is shown that well-defined holonomies can be assigned by using Uhlmann's ... More
Experimentally testable geometric phase of sequences of Everett's relative quantum statesMar 09 2009May 25 2009Everett's concept of relative state is used to introduce a geometric phase that depends nontrivially on entanglement in a pure quantum state. We show that this phase can be measured in multiparticle interferometry. A correlation-dependent generalization ... More
Geometric phase in weak measurementsApr 06 2006Sep 27 2006Pancharatnam's geometric phase is associated with the phase of a complex-valued weak value arising in a certain type of weak measurement in pre- and post-selected quantum ensembles. This makes it possible to test the nontransitive nature of the relative ... More
Geometric phases in quantum informationMar 16 2015Oct 07 2015The rise of quantum information science has opened up a new venue for applications of the geometric phase (GP), as well as triggered new insights into its physical, mathematical, and conceptual nature. Here, we review this development by focusing on three ... More
Nonadiabatic holonomic single-qubit gates in off-resonant $Λ$ systemsNov 03 2015We generalize nonadiabatic holonomic quantum computation in a resonant $\Lambda$ configuration proposed in [New J. Phys. 14 (2012) 103035] to the case of off-resonant driving lasers. We show that any single-qubit holonomic gate can be realized by separately ... More
Stabilised finite element methods for ill-posed problems with conditional stabilityDec 09 2015In this paper we discuss the adjoint stabilised finite element method introduced in, E. Burman, Stabilized finite element methods for nonsymmetric, noncoercive and ill-posed problems. Part I: elliptic equations, SIAM Journal on Scientific Computing, and ... More
The Baltic Meetings 1957 to 1967Dec 07 2015The Baltic meetings of astronomers from Northern Germany and Scandinavia began in 1957 and gathered up to 70 participants. Reports of the presentations are available from all meetings, providing an overview of the interests of astronomers in this part ... More
Young astronomer in Denmark 1946 to 1958Dec 07 2015This is a personal account of how I became an astronomer. Fascinated by the stars and planets in the dark sky over Lolland, an island 100 km south of Copenhagen, the interest in astronomy was growing. Encouraged by my teachers, I polished mirrors and ... More
Asymptotic degree distribution of a duplication-deletion random graph modelAug 19 2014We study a discrete-time duplication-deletion random graph model and analyse its asymptotic degree distribution. The random graphs consists of disjoint cliques. In each time step either a new vertex is brought in with probability $0<p<1$ and attached ... More
Classical Black Holes Are HotAug 16 2014Nov 09 2014In the early 1970s it is was realized that there is a striking formal analogy between the Laws of black-hole mechanics and the Laws of classical thermodynamics. Before the discovery of Hawking radiation, however, it was generally thought that the analogy ... More
Tight asymptotic key rate for the BB84 protocol with local randomisation and device imprecisionsMay 22 2014Aug 04 2014Local randomisation is a preprocessing procedure in which one of the legitimate parties of a quantum key distribution (QKD) scheme adds noise to their version of the key and was found by Kraus et al. [Phys. Rev. Lett. 95, 080501 (2005)] to improve the ... More
Henstock--Kurzweil Fourier transformsDec 07 2002The Fourier transform is considered as a Henstock--Kurzweil integral. Sufficient conditions are given for the existence of the Fourier transform and necessary and sufficient conditions are given for it to be continuous. The Riemann--Lebesgue lemma fails: ... More
The $L^p$ primitive integralAug 17 2012For each $1\leq p<\infty$ a space of integrable Schwartz distributions, $L^'^{\,p}$, is defined by taking the distributional derivative of all functions in $L^p$. Here, $L^p$ is with respect to Lebesgue measure on the real line. If $f\in L^'^{\,p}$ such ... More
Integrals and Banach spaces for finite order distributionsOct 17 2011Let $\Bc$ denote the real-valued functions continuous on the extended real line and vanishing at $-\infty$. Let $\Br$ denote the functions that are left continuous, have a right limit at each point and vanish at $-\infty$. Define $\acn$ to be the space ... More
Convolutions with the continuous primitive integralSep 23 2009If $F$ is a continuous function on the real line and $f=F'$ is its distributional derivative then the continuous primitive integral of distribution $f$ is $\int_a^bf=F(b)-F(a)$. This integral contains the Lebesgue, Henstock--Kurzweil and wide Denjoy integrals. ... More
Stabilised finite element methods for non-symmetric, non-coercive and ill-posed problems. Part I: elliptic equationsApr 08 2013Aug 02 2013In this paper we propose a new method to stabilise non-symmetric indefinite problems. The idea is to solve a forward and an adjoint problem simultaneously using a suitable stabilised finite element method. Both stabilisation of the element residual and ... More
The dominating colour of an infinite Pólya urn modelJun 19 2015Jun 29 2015We study a P\'olya-type urn model defined as follows. Start at time 0 with a single ball of some colour. Then, at each time n>0, choose a ball from the urn uniformly at random. With probability 1/2<p<1, return the ball to the urn along with another ball ... More
Vertex Operators and Moduli Spaces of SheavesJun 09 2009The Nekrasov partition function in supersymmetric quantum gauge theory is mathematically formulated as an equivariant integral over certain moduli spaces of sheaves on a complex surface. In ``Seiberg-Witten Theory and Random Partitions'', Nekrasov and ... More
Projection stabilisation of Lagrange multipliers for the imposition of constraints on interfaces and boundariesMar 19 2012Aug 02 2013Projection stabilisation applied to general Lagrange multiplier finite element methods is introduced and analysed in an abstract framework. We then consider some applications of the stabilised methods: (i) the weak imposition of boundary conditions, (ii) ... More
A penalty free non-symmetric Nitsche type method for the weak imposition of boundary conditionsJun 28 2011Nov 04 2011In this note we show that the non-symmetric version of the classical Nitsche's method for the weak imposition of boundary conditions is stable without penalty term. We prove optimal $H^1$-error estimates and $L^2$-estimates that are suboptimal with half ... More
A note on acoustic turbulenceJun 13 2019We consider a three-dimensional acoustic field of an ideal gas in which all entropy production is confined to weak shocks and show that similar scaling relations hold for such a field as for forced Burgers turbulence, where the shock amplitude scales ... More
Categories with families, FOLDS and logic enriched type theoryMay 05 2016Categories with families (cwfs) is an established semantical structure for dependent type theories, such as Martin-L\"of type theory. Makkai's first-order logic with dependent sorts (FOLDS) is an example of a so-called logic enriched type theory. We introduce ... More
Robust error estimates in weak norms for advection dominated transport problems with rough dataMar 08 2013May 02 2014We consider mixing problems in the form of transient convection--diffusion equations with a velocity vector field with multiscale character and rough data. We assume that the velocity field has two scales, a coarse scale with slow spatial variation, which ... More
Stabilized finite element methods for nonsymmetric, noncoercive and ill-posed problem. Part II: hyperbolic equationsAug 02 2013May 02 2014In this paper we consider stabilised finite element methods for hyperbolic transport equations without coercivity. Abstract conditions for the convergence of the methods are introduced and these conditions are shown to hold for three different stabilised ... More
Commutator inequalities via Schur productsDec 15 2015For a self-adjoint unbounded operator D on a Hilbert space H, a bounded operator y on H and some complex Borel functions g(t) we establish inequalities of the type ||[g(D),y]|| \leq A|||y|| + B||[D,y]|| + ...+ X|[D, [D,...[D, y]...]]||. The proofs take ... More
Jensen's Σ^* theory and the combinatorial content of V=LDec 02 1992The purpose of this article is to indicate how a reformulation of Jensen's $\Sigma^*$ theory (developed for the study of core models) can be used to provide a more satisfactory treatment of uniformization, hulls and Skolem functions for the $J_\alpha$'s. ... More
Easton supported Jensen coding and projective measure without projective BaireJan 27 2014We prove that it is consistent relative to a Mahlo cardinal that all sets of reals definable from countable sequences of ordinals are Lebesgue measurable, but at the same time, there is a $\Delta^1_3$ set without the Baire property. To this end, we introduce ... More
A large Pi-1-2 set absolute for set forcingDec 02 1992Let k be a definable L-cardinal. Then there is a set of reals X, class-generic over L, such that L(X) and L have the same cardinals, X has size k in L(X) and some pi-1-2 formula defines X in all set-generic extensions of L(X). Two corollaries, both assuming ... More
Minimal universesNov 24 1992An inner model M is MINIMAL if there is a class A such that <M,A> is amenable yet has no transitive proper elementary submodel. We study minimal universes in the context of 0#. For example we prove: If 0# exists then there is an inner model which is minimal ... More
Generalized integrands and bond portfolios: Pitfalls and counter examplesSep 12 2009Jan 05 2011We construct Zero-Coupon Bond markets driven by a cylindrical Brownian motion in which the notion of generalized portfolio has important flaws: There exist bounded smooth random variables with generalized hedging portfolios for which the price of their ... More
Detection of a Hypercharge Axion in ATLASMay 28 2001This Master of Science thesis treats the hypercharge axion, which is a hypothetical pseudo-scalar particle with electroweak interactions. First, the theoretical context and the motivations for this study are discussed. In short, the hypercharge axion ... More
Tomography of random social networksSep 15 2005We study the statistical properties of large random networks with specified degree distributions. New techniques are presented for analyzing the structure of social networks. Specifically, we address the question of how many nodes exist at a distance ... More