Results for "Joachim Berg"

total 3285took 0.10s
Sparse geometric graphs with small dilationFeb 14 2007Jun 26 2007Given a set S of n points in R^D, and an integer k such that 0 <= k < n, we show that a geometric graph with vertex set S, at most n - 1 + k edges, maximum degree five, and dilation O(n / (k+1)) can be computed in time O(n log n). For any k, we also construct ... More
Evolved Art with Transparent, Overlapping, and Geometric ShapesApr 12 2019In this work, an evolutionary art project is presented where images are approximated by transparent, overlapping and geometric shapes of different types, e.g., polygons, circles, lines. Genotypes representing features and order of the geometric shapes ... More
Modeling, shape analysis and computation of the equilibrium pore shape near a PEM-PEM intersectionMay 28 2014In this paper we study the equilibrium shape of an interface that represents the lateral boundary of a pore channel embedded in an elastomer. The model consists of a system of PDEs, comprising a linear elasticity equation for displacements within the ... More
Crystal rules for $(\ell,0)$-JM partitionsJul 19 2011Vazirani and the author \cite{BV} gave a new interpretation of what we called $\ell$-partitions, also known as $(\ell,0)$-Carter partitions. The primary interpretation of such a partition $\lambda$ is that it corresponds to a Specht module $S^{\lambda}$ ... More
Integral representation of some functions related to the Gamma functionNov 24 2004We prove that the functions Phi(x)=[Gamma(x+1)]^{1/x}(1+1/x)^x/x and log Phi(x) are Stieltjes transforms.
A quantum algorithm for the quantum Schur-Weyl transformMay 17 2012We construct an efficient quantum algorithm to compute the quantum Schur-Weyl transform for any value of the quantum parameter $q \in [0,\infty]$. Our algorithm is a $q$-deformation of the Bacon-Chuang-Harrow algorithm, in the sense that it has the same ... More
Fibonacci numbers and orthogonal polynomialsSep 11 2006Aug 05 2010We prove that the sequence $(1/F_{n+2})_{n\ge 0}$ of reciprocals of the Fibonacci numbers is a moment sequence of a certain discrete probability, and we identify the orthogonal polynomials as little $q$-Jacobi polynomials with $q=(1-\sqrt{5})/(1+\sqrt{5})$. ... More
Combinatorics of $(\ell,0)$-JM partitions, $\ell$-cores, the ladder crystal and the finite Hecke algebraJun 08 2009The following thesis contains results on the combinatorial representation theory of the finite Hecke algebra $H_n(q)$. In Chapter 2 simple combinatorial descriptions are given which determine when a Specht module corresponding to a partition $\lambda$ ... More
Pervasive adaptation of gene expression in DrosophilaFeb 23 2015Apr 03 2015Gene expression levels are important molecular quantitative traits that link genotypes to molecular functions and fitness. In Drosophila, population-genetic studies in recent years have revealed substantial adaptive evolution at the genomic level. However, ... More
Finding Pairwise Intersections Inside a Query RangeFeb 21 2015We study the following problem: preprocess a set O of objects into a data structure that allows us to efficiently report all pairs of objects from O that intersect inside an axis-aligned query range Q. We present data structures of size $O(n({\rm polylog} ... More
Mossbauer neutrinos in quantum mechanics and quantum field theoryApr 28 2009Jun 12 2009We demonstrate the correspondence between quantum mechanical and quantum field theoretical descriptions of Mossbauer neutrino oscillations. First, we compute the combined rate $\Gamma$ of Mossbauer neutrino emission, propagation, and detection in quantum ... More
Free Choice Petri Nets without frozen tokens and Bipolar Synchronization SystemsSep 17 2006Sep 10 2007Bipolar synchronization systems (BP-systems) constitute a class of coloured Petri nets, well suited for modeling the control flow of discrete, dynamical systems. Every BP-system has an underlying ordinary Petri net, which is a T-system. Moreover, it has ... More
Comment on "Dynamic Scaling of Non-Euclidean Interfaces" [arXiv:0804.1898]Oct 27 2008Feb 23 2009This is the revised version of a Comment on a paper by C. Escudero (Phys. Rev. Lett. 100, 116101, 2008; arXiv:0804.1898).
Lonely adatoms in spaceFeb 14 2003There is a close relation between the problems of second layer nucleation in epitaxial crystal growth and chemical surface reactions, such as hydrogen recombination, on interstellar dust grains. In both cases standard rate equation analysis has been found ... More
Stochastic Calculus with respect to Gaussian ProcessesAug 05 2014May 20 2015Stochastic integration with respect to Gaussian processes, such as fractional Brownian motion (fBm) or multifractional Brownian motion (mBm), has raised strong interest in recent years, motivated in particular by applications in finance, Internet traffic ... More
Skin Structures in Scalar Curvature GeometryDec 27 2015This is the third in a series of papers on the geometry and analysis of singular area minimizing hypersurfaces. We show how to derive obstruction and structure theories for scalar curvature constraints without imposing dimensional or topological restrictions ... More
Schatten properties, nuclearity and minimality of shift invariant spacesMay 10 2016Nov 10 2016We extend Feichtinger's minimality property on smallest non-trivial time-frequency shift invariant Banach spaces, to the quasi-Banach case. Analogous properties are deduced for certain matrix classes. We use these results to prove that $\operatorname{Op}(a)$ ... More
Evolutionary Model of Stock MarketsMay 15 2015The paper presents an evolutionary economic model for the price evolution of stocks. Treating a stock market as a self-organized system governed by a fast purchase process and slow variations of demand and supply the model suggests that the short term ... More
Canonical transformations for fermions in superanalysisApr 08 2013Apr 29 2013Canonical transformations (Bogoliubov transformations) for fermions with an infinite number of degrees of freedom are studied within a calculus of superanalysis. A continuous representation of the orthogonal group is constructed on a Grassmann module ... More
Gravitational potential energy group theoreticallyApr 30 2003May 05 2003We show by symplectically realizing the one spatial Aristotle Lie group that the hamiltonian of the associated elementary system consist of a gravitational energy only. No kinetic term.
Images of function and distribution spaces under the Bargmann transformSep 18 2014Jun 08 2016We consider a broad family of test function spaces and their dual (distribution) space. The family includes Gelfand-Shilov spaces, a family of test function spaces introduced by S. Pilipovic. We deduce different characterizations of such spaces, especially ... More
Arason's filtration of the Witt group of dyadic valued fieldsJan 03 2019Jan 04 2019Generalizing a theorem of Springer, we construct an extended Arason filtration by subgroups for the Witt group of quadratic forms of a general valued field, relating these subgroups with Witt-like groups of the residue field, in arbitrary characteristic. ... More
On the number of isolated eigenvalues of a pair of particles in a quantum wireDec 31 2018In this note we consider a pair of particles moving on the positive half-line with the pairing generated by a hard-wall potential. This model was first introduced in [arXiv:1604.06693] and later applied to investigate condensation of pairs of electrons ... More
On rational functions with monodromy group $M_{11}$Mar 23 2015Dec 14 2015We compute new polynomials with Galois group $M_{11}$ over $\mathbb{Q}(t)$. These polynomials stem from various families of covers of $\mathbb{P}^1\mathbb{C}$ ramified over at least 4 points. Each of these families has features that make a detailed study ... More
Cospan construction of the graph category of Borisov and ManinNov 30 2016Dec 13 2016It is shown how the graph category of Borisov and Manin can be constructed from (a variant of) the graph category of Joyal and Kock, essentially by reversing the generic morphisms. More precisely, the morphisms in the Borisov-Manin category are exhibited ... More
From Möbius inversion to renormalisationSep 04 2018This paper traces a straight line from classical M\"obius inversion to Hopf-algebraic perturbative renormalisation. This line, which is logical but not entirely historical, consists of just a few main abstraction steps, and some intermediate steps dwelled ... More
Power laws in surface physics: The deep, the shallow and the usefulMar 10 2004The growth and dynamics of solid surfaces displays a multitude of power law relationships, which are often associated with geometric self-similarity. In many cases the mechanisms behind these power laws are comparatively trivial, and require little more ... More
New mechanism for impurity-induced step bunchingFeb 28 2002Jul 25 2002Codeposition of impurities during the growth of a vicinal surface leads to an impurity concentration gradient on the terraces, which induces corresponding gradients in the mobility and the chemical potential of the adatoms. Here it is shown that the two ... More
Records in a changing worldFeb 06 2007In the context of this paper, a record is an entry in a sequence of random variables (RV's) that is larger or smaller than all previous entries. After a brief review of the classic theory of records, which is largely restricted to sequences of independent ... More
Sequence-specific size, structure, and stability of tight protein knotsSep 04 2008Approximately 1% of the known protein structures display knotted configurations in their native fold but their function is not understood. It has been speculated that the entanglement may inhibit mechanical protein unfolding or transport, e.g., as in ... More
New signals in dark matter detectorsOct 09 2012We investigate the scattering of solar neutrinos on electrons and nuclei in dark matter direct detection experiments. The rates of these processes are small in the Standard Model, but can be enhanced by several orders of magnitude if the neutrino sector ... More
Statistical Physics of Biological EvolutionApr 12 2012This is an extended abstract of lectures delivered at the 4th Warsaw Summer School on Statistical Physics in Kazimierz Dolny, June 25-July 2, 2011.
Conditional Elimination through Code DuplicationJun 15 2011We propose an optimizing transformation which reduces program runtime at the expense of program size by eliminating conditional jumps.
Collider limits on dark matterMay 17 2011Dark matter pair production at high energy colliders may leave observable signatures in the energy and momentum spectra of the objects recoiling against the dark matter. We discuss signatures of Dark Matter in the jets + missing energy and photon + missing ... More
VSPs of cubic fourfolds and the Gorenstein locus of the Hilbert scheme of 14 points on A^6Nov 14 2016This paper is concerned with the geometry of the Gorenstein locus of the Hilbert scheme of $14$ points on $\mathbb{A}^6$. This scheme has two components: the smoothable one and an exceptional one. We prove that the latter is smooth and identify the intersection ... More
Wiener estimates on modulation spacesMar 19 2019We characterise modulation spaces by suitable Wiener estimates on the short-time Fourier transforms of the involved functions and distributions. We use the results to refine some formulae on periodic distributions with Lebesgue estimates on their coefficients. ... More
Bound states of two-dimensional Schrödinger-Newton equationsJul 25 2008We prove an existence and uniqueness result for ground states and for purely angular excitations of two-dimensional Schr\"{o}dinger-Newton equations. From the minimization problem for ground states we obtain a sharp version of a logarithmic Hardy-Littlewood-Sobolev ... More
Mass, Impetus and Force by Symplectic Realizations of the Static GroupSep 13 2005We show by symplectic realizations of the one dimensional Static group $G$ that the maximal $G$-elementary system is a a massive particle under an invariant force $f$ participating in the linear momentum and an invariant impetus $I$ participating in the ... More
VSPs of cubic fourfolds and the Gorenstein locus of the Hilbert scheme of 14 points on A^6Nov 14 2016Apr 27 2018This paper is concerned with the geometry of the Gorenstein locus of the Hilbert scheme of $14$ points on $\mathbb{A}^6$. This scheme has two components: the smoothable one and an exceptional one. We prove that the latter is smooth and identify the intersection ... More
Accessibility percolation in random fitness landscapesMar 28 2019The fitness landscape encodes the mapping of genotypes to fitness and provides a succinct representation of possible trajectories followed by an evolving population. Evolutionary accessibility is quantified by the existence of fitness-monotonic paths ... More
Measurement of b-Baryons with the CDF II detectorOct 02 2007We report the observation of new bottom baryon states. The most recent result is the observation of the baryon \Xi_b^- through the decay \Xi_b^- to J/\psi \Xi^-. The significance of the signal corresponds to 7.7 sigma and the \Xi_b^- mass is measured ... More
Morphisms of Coloured Petri NetsAug 07 2006We introduce the concept of a morphism between coloured nets. Our definition generalizes Petris definition for ordinary nets. A morphism of coloured nets maps the topological space of the underlying undirected net as well as the kernel and cokernel of ... More
Products on Schatten-von Neumann classes and modulation spacesFeb 16 2009We consider modulation space and spaces of Schatten-von Neumann symbols where corresponding pseudo-differential operators map one Hilbert space to another. We prove H\"older-Young and Young type results for such spaces under dilated convolutions and multiplications. ... More
Comment on ``Determination of Interlayer Diffusion Parameters for Ag(111)''Aug 30 2000Mar 15 2001A Comment on PRL 85, 1480 (2000) by K.R. Roos and M.C. Tringides.
Polynomial functors and combinatorial Dyson-Schwinger equationsDec 09 2015Oct 03 2016We present a general abstract framework for combinatorial Dyson-Schwinger equations, in which combinatorial identities are lifted to explicit bijections of sets, and more generally equivalences of groupoids. Key features of combinatorial Dyson-Schwinger ... More
Dynamic Model of Markets of Homogenous Non-DurableSep 27 2011Jul 27 2015A new microeconomic model is presented that aims at a description of the long-term unit sales and price evolution of homogeneous non-durable goods in polypoly markets. It merges the product lifecycle approach with the price dispersion dynamics of homogeneous ... More
Tangency quantum cohomologyJun 20 2000Let X be a smooth projective variety. Using modified psi classes on the stack of genus zero stable maps to X, a new associative quantum product is constructed on the cohomology space of X. When X is a homogeneous variety, this structure encodes the characteristic ... More
Note on commutativity in double semigroups and two-fold monoidal categoriesAug 17 2006A concrete computation -- twelve slidings with sixteen tiles -- reveals that certain commutativity phenomena occur in every double semigroup. This can be seen as a sort of Eckmann-Hilton argument, but it does not use units. The result implies in particular ... More
Polynomial functors and treesJul 17 2008Dec 03 2009We explore the relationship between polynomial functors and (rooted) trees. In the first part we use polynomial functors to derive a new convenient formalism for trees, and obtain a natural and conceptual construction of the category $\Omega$ of Moerdijk ... More
The incompleteness of an incompleteness argumentApr 18 2019G\"odel's argument for the First Incompleteness Theorem is, structurally, a proof by contradiction. This article intends to reframe the argument by, first, isolating an additional assumption the argument relies on, and then, second, arguing that the contradiction ... More
A new Approach to the N-particle Problem in QMNov 08 2012Jun 12 2013In this paper the old problem of determining the discrete spectrum of a multi-particle Hamiltonian is reconsidered. The aim is to bring a fermionic Hamiltonian for large numbers N of particles by analytical means into a shape such that modern numerical ... More
Tackling the testing migration problem with SAT-SolversApr 13 2012We show that it is feasible to formulate the testing migration problem as a practically solvable PMAX-SAT instance, when package dependencies and conflicts are pre-processed sensibly.
The charm-quark contribution to epsilon_K and Delta M_KNov 06 2011Neutral Kaon mixing plays an important role in the phenomenology of the standard model and its extensions because of its sensitivity to high-energy scales. In particular epsilon_K, parameterising indirect CP violation in the neutral Kaon system, serves ... More
Diffusion in the general theory of relativityMar 19 2010The Markovian diffusion theory in the phase space is generalized within the framework of the general theory of relativity. The introduction of moving orthonormal frame vectors both for the position as well the velocity space enables to bypass difficulties ... More
The Product Life Cycle of Durable GoodsSep 05 2011Sep 11 2015A dynamic model of the product lifecycle of (nearly) homogeneous durables in polypoly markets is established. It describes the concurrent evolution of the unit sales and price of durable goods. The theory is based on the idea that the sales dynamics is ... More
Efficient numerical diagonalization of hermitian 3x3 matricesOct 24 2006Jul 04 2008A very common problem in science is the numerical diagonalization of symmetric or hermitian 3x3 matrices. Since standard "black box" packages may be too inefficient if the number of matrices is large, we study several alternatives. We consider optimized ... More
Interface dynamics of microscopic cavities in waterApr 02 2007An analytical description of the interface motion of a collapsing nanometer-sized spherical cavity in water is presented by a modification of the Rayleigh-Plesset equation in conjunction with explicit solvent molecular dynamics simulations. Quantitative ... More
Introduction to Step Dynamics and Step InstabilitiesMay 04 2004This paper provides an elementary introduction to the basic concepts used in describing epitaxial crystal growth in terms of the thermodynamics and kinetics of atomic steps. Selected applications to morphological instabilities of stepped surfaces are ... More
Tempo and mode in quasispecies evolutionMar 21 2001Evolutionary dynamics in an uncorrelated rugged fitness landscape is studied in the framework of Eigen's molecular quasispecies model. We consider the case of strong selection, which is analogous to the zero temperature limit in the equivalent problem ... More
Scaling regimes for second layer nucleationAug 30 2000Nucleation on top of two-dimensional islands with step edge barriers is investigated using scaling arguments. The nucleation rate is expressed in terms of three basic time scales: The time interval between deposition events, the residence time of atoms ... More
Spiral growth, two-dimensional nucleation, and the Ehrlich-Schwoebel effectSep 13 2007Frank's prediction of the spiral growth mode in 1949 defined a pivotal moment in the history of crystal growth. In recent decades the topic has received less attention, and instead we have seen a resurrection of two-dimensional nucleation theory in the ... More
Four Lectures on the Physics of Crystal GrowthJun 21 2002Several aspects of the theory of epitaxial crystal growth from atomic or molecular beams are developed from the perspective of statistical physics. Lectures are devoted to the rate equation theory of two-dimensional nucleation and its limitations; the ... More
Coarsening of vortex ripples in sandAug 28 2001The coarsening of an array of vortex ripples prepared in an unstable state is discussed within the framework of a simple mass transfer model first introduced by K.H. Andersen et al. [Phys. Rev. E 63, 066308 (2001)]. Two scenarios for the selection of ... More
An upper bound for the Waring rank of a formMay 29 2013In this paper we introduce the open Waring rank of a form of degree d in n variables and prove the that this rank in bounded from above by \binom{n+d-2}{d-1} - \binom{n+d-6}{d-3} whenever n, d >= 3. This proves the same upper bound for the classical Waring ... More
Elementary components of Hilbert schemesOct 17 2017Feb 01 2019We generalize the Bialynicki-Birula decomposition to singular schemes and apply it to the Hilbert scheme of points on an affine space. We find an infinite family of small, elementary and generically smooth components of the Hilbert scheme of points of ... More
On the existence of weak solutions of a thermistor system with p-Laplacian type equation: the unsteady caseApr 25 2016We consider an unsteady thermistor system with a p-Laplace type equation for the electrostatic potential.
Stability of Spherically Symmetric Wave MapsMar 02 2005We study Wave Maps from R^{2+1} to the hyperbolic plane with smooth compactly supported initial data which are close to smooth spherically symmetric ones with respect to some H^{1+\mu}, \mu>0. We show that such Wave Maps don't develop singularities and ... More
Method LACJul 29 2005This is a paper which present a mnemotechnical method that we call LAC for Lists, Arrangements and Combinations. It can help students or any one to recollect formulae from combinatorial theory ([1],[2],[3],[4]) without an a priori memorization of them. ... More
Pathologies on the Hilbert scheme of pointsDec 20 2018We prove that the Hilbert scheme of points on a higher dimensional affine space is non-reduced and has components lying entirely in characteristic p for all primes p. In fact, we show that Vakil's Murphy's Law holds up to retraction for this scheme. Our ... More
Deformations of zero-dimensional schemes and applicationsJul 30 2013Apr 02 2014In this thesis we consider the geometry of the Hilbert scheme of points in P^n, concentrating on the locus of points corresponding to the Gorenstein subschemes of P^n. New results are given, most importantly we provide tools for constructing flat families ... More
A remark on the effect of random singular two-particle interactionsJul 04 2017In this note we study a two-particle bound system (molecule) moving on the positive half-line under the influence of randomly distributed singular two-particle interactions generated by a Poisson process. We give a rigorous definition of the underlying ... More
Computation of Hurwitz spaces and new explicit polynomials for almost simple Galois groupsDec 17 2015We compute the first explicit polynomials with Galois groups $G=P\Gamma L_3(4)$, $PGL_3(4)$, $PSL_3(4)$ and $PSL_5(2)$ over $\mathbb{Q}(t)$. Furthermore we compute the first examples of totally real polynomials with Galois groups $PGL_2(11)$, $PSL_3(3)$, ... More
On the mod-$p$ distribution of discriminants of $G$-extensionsFeb 15 2019This paper was motivated by a recent paper by Krumm and Pollack investigating modulo-$p$ behaviour of quadratic twists with rational points of a given hyperelliptic curve, conditional on the abc-conjecture. We extend those results to twisted Galois covers ... More
Diffusion in the special theory of relativityMar 04 2009The Markovian diffusion theory is generalized within the framework of the special theory of relativity using a modification of the mathematical calculus of diffusion on Riemannian manifolds (with definite metric) to describe diffusion on Lorentzian manifolds ... More
A Star Product for Complex Grasmann ManifoldsSep 13 1997We explicitly construct a star product for the complex Grassmann manifolds using the method of phase space reduction. Functions on $\mathbb{C}^{(p+q)\cdot p~*}$, the space of $(p+q)\times p$ matrices of rank p, invariant under the right action of $Gl(p,\mathbb{C})$ ... More
On commutativity of ideal extensionsMay 14 2013In this paper we examine the commutativity of ideal extensions. We introduce methods of constructing such extensions, in particular we construct a noncommutative ring T which contains a central and idempotent ideal I such that T/I is a field. This answers ... More
The Zak transform and Wiener estimates on Gelfand-Shilov and modulation spacesMay 28 2017Mar 01 2019We characterise modulation spaces by suitable Wiener estimates on the short-time Fourier transforms of the involved functions and distributions. We use the results to characterise modulation spaces by suitable estimates on the short-time Fourier transform ... More
Local Times of Gaussian ProcessesMar 15 2017The aim of this work is to define and perform a study of local times of all Gaussian processes that have an integral representation over a real interval (that maybe infinite). Very rich, this class of Gaussian processes, contains Volterra processes (and ... More
Theory News HiggsSep 16 2016I review new developments in Higgs physics, with a focus on Yukawa couplings in and beyond the standard model. In particular, I discuss different methods of measuring the light Yukawas, new sources of CP violation in the Higgs sector, and lepton flavor ... More
Flavor Violation in the Scalar SectorMay 10 2016In many extensions of the Standard Model, the alignment in flavor space of the fermion mass matrices and the Yukawa coupling matrices can be broken. The physical scalar boson $h(125)$ could then have flavor changing couplings. In this talk, we summarize ... More
Viscous and Gravitational Fingering in Multiphase Compositional and Compressible FlowJan 12 2016Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for 1) single-phase flow (e.g., contaminant ... More
Combinatorial Dyson-Schwinger equations and inductive data typesDec 24 2015The goal of this contribution is to explain the analogy between combinatorial Dyson-Schwinger equations and inductive data types to a readership of mathematical physicists. The connection relies on an interpretation of combinatorial Dyson-Schwinger equations ... More
Electroweak effects in the extraction of the CKM angle $γ$ from $B \to D π$ decaysDec 10 2014Feb 23 2015The angle $\gamma$ of the standard CKM unitarity triangle can be determined from tree-level $B$-meson decays essentially without hadronic uncertainties. We calculate the second-order electroweak corrections for the $B \to D \pi$ modes and show that their ... More
Quantized Polar Code Decoders: Analysis and DesignFeb 27 2019Applications of massive machine-type communications, such as sensor networks, smart metering, 'internet-of-things', or process and factory automation, are forecast to have great economic impact in the next five to ten years. Low-complexity energy- and ... More
Population Genetics and EvolutionMar 22 2018These lecture notes introduce key concepts of mathematical population genetics within the most elementary setting and describe a few recent applications to microbial evolution experiments. Pointers to the literature for further reading are provided, and ... More
Continuity and Schatten properties for pseudo-differential operators with symbols in quasi-Banach modulation spaces or Hörmander classesJun 15 2014Apr 29 2016We establish continuity and Schatten-von Neumann properties for matrix operators with matrices satisfying mixed quasi-norm estimates. These considerations also include the case when the Lebesgue and Schatten parameters are allowed to stay between $0$ ... More
The Correctness of Launchbury's Natural Semantics for Lazy EvaluationMay 13 2014In his seminal paper "A Natural Semantics for Lazy Evaluation", John Launchbury proves his semantics correct with respect to a denotational semantics. We machine-checked the proof and found it to fail, and provide two ways to fix it: One by taking a detour ... More
From Stochastic Integration wrt Fractional Brownian Motion to Stochastic Integration wrt Multifractional Brownian MotionMay 02 2013Stochastic integration w.r.t. fractional Brownian motion (fBm) has raised strong interest in recent years, motivated in particular by applications in finance and Internet traffic modelling. Since fBm is not a semi-martingale, stochastic integration requires ... More
Constraints on dark matter annihilation from AMS-02 resultsApr 03 2013Oct 30 2013We use recently released data on the positron-to-electron ratio in cosmic rays from the AMS-02 experiment to constrain dark matter annihilation in the Milky Way. Due to the yet unexplained positron excess, limits are generally weaker than those obtained ... More
Solvability of Generalized Monomial GroupsJan 22 2009The solvability of monomial groups is a well-known result in character theory. Certain properties of Artin L-series suggest a generalization of these groups, namely to such groups where every irreducible character has some multiple which is induced from ... More
Categorification of Hopf algebras of rooted treesSep 27 2011Apr 28 2012We exhibit a monoidal structure on the category of finite sets indexed by P-trees for a finitary polynomial endofunctor P. This structure categorifies the monoid scheme (over Spec N) whose semiring of functions is (a P-version of) the Connes--Kreimer ... More
Polynomial functors and combinatorial Dyson-Schwinger equationsDec 09 2015Feb 01 2017We present a general abstract framework for combinatorial Dyson-Schwinger equations, in which combinatorial identities are lifted to explicit bijections of sets, and more generally equivalences of groupoids. Key features of combinatorial Dyson-Schwinger ... More
Homogenization of a catalyst layer model for periodically distributed pore geometries in PEM fuel cellsApr 30 2012We formally derive an effective catalyst layer model comprising the reduction of oxygen for periodically distributed pore geometries. By assumption, the pores are completely filled with water and the surrounding walls consist of catalyst particles which ... More
A topos for a nonstandard functional interpretationJan 16 2013We introduce a new topos in order to give a semantic account of the nonstandard functional interpretation introduced by Eyvind Briseid, Pavol Safarik and the author.
A Hybrid Quasi-Newton Projected-Gradient Method with Application to Lasso and Basis-Pursuit DenoiseNov 16 2016We propose a new algorithm for the optimization of convex functions over a polyhedral set in Rn. The algorithm extends the spectral projected-gradient method with limited-memory BFGS iterates restricted to the present face whenever possible. We prove ... More
Quasi-symmetric and non-commutative affine Schur functionsMay 10 2012We introduce dual Hopf algebras which simultaneously combine the concepts of the k-Schur function theory with the quasi-symmetric Schur function theory. We construct dual basis of these Hopf algebras with remarkable properties.
Path categories and propositional identity typesApr 20 2016Sep 20 2016Connections between homotopy theory and type theory have recently attracted a lot of attention, with Voevodsky's univalent foundations and the interpretation of Martin-Lof's identity types in Quillen model categories as some of the highlights. In this ... More
The Herbrand ToposDec 16 2011Apr 18 2013We define a new topos, the Herbrand topos, inspired by the modified realizability topos and our earlier work on Herbrand realizability. We also introduce the category of Herbrand assemblies and characterise these as the double-negation-separated objects ... More
Heat flow in Riemannian manifolds with non-negative Ricci curvatureJun 23 2015Aug 03 2016Let $\Omega$ be an open set in a geodesically complete, non-compact, $m$-dimen-sional Riemannian manifold $M$ with non-negative Ricci curvature, and without boundary. We study the heat flow from $\Omega$ into $M-\Omega$ if the initial temperature distribution ... More
On the minimization of Dirichlet eigenvaluesMay 01 2014Oct 29 2014Results are obtained for two minimization problems: $$I_k(c)=\inf \{\lambda_k(\Omega): \Omega\ \textup{open, convex in}\ \mathbb{R}^m,\ \mathcal{T}(\Omega)= c \},$$ and $$J_k(c)=\inf\{\lambda_k(\Omega): \Omega\ \textup{quasi-open in}\ \mathbb{R}^m, |\Omega|\le ... More