Results for "Tim C Kietzmann"

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Recurrence required to capture the dynamic computations of the human ventral visual streamMar 14 2019The visual system is an intricate network of brain regions that enables us to recognize the world around us. Despite its abundant lateral and feedback connections, human object processing is commonly viewed and studied as a feedforward process. Here, ... More
Additive Deformations of Braided Hopf AlgebrasApr 08 2011Additive deformations of bialgebras in the sense of J. Wirth, i.e. deformations of the multiplication map fulfilling a certain compatibility condition w.r.t. the coalgebra structure, can be generalized to braided bialgebras. The theorems for additive ... More
The Phenomenology of Single Top Quark Production at the Fermilab TevatronOct 16 1997Single top quark production at the Fermilab Tevatron Run II (a p \bar{p} collider with \sqrt{S} = 2 TeV) proceeds dominantly via two sub-processes, a t-channel W-gluon fusion process, and an s-channel W^* process. We show that these two sub-processes ... More
Assessing Developer Beliefs: A Reply to "Perceptions, Expectations, and Challenges in Defect Prediction"Apr 11 2019It can be insightful to extend qualitative studies with a secondary quantitative analysis (where the former suggests insightful questions that the latter can answer). Documenting developer beliefs should be the start, not the end, of Software Engineering ... More
Anomalous t-c-g coupling: The connection between single top production and top decayNov 05 1996Continuing earlier work, we examine the constraint on an anomalous t-c-g coupling from top quark decay. We find that from current CDF measurements of the branching ratio $t \rightarrow W b$, the minimum scale at which new physics can strongly modify the ... More
Finite-size effects for anisotropic bootstrap percolation: logarithmic correctionsFeb 06 2007In this note we analyze an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced ... More
Atomic force microscopy (AFM) study of thick lamellar stacks of phospholipid bilayersJun 01 2007We report an Atomic Force Microscopy (AFM) study on thick multi lamellar stacks of approx. 10 mum thickness (about 1500 stacked membranes) of DMPC (1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine) deposited on silicon wafers. These thick stacks could ... More
Anomalous W^+ W^- t {\bar t} Couplings at the e^+ e^- Linear ColliderSep 11 1997We study production of t {\bar t} via W^+ W^- fusion, including the relevant backgrounds at the proposed Linear Collider (an e^+ e^- collider with \sqrt{S} = 1.5 TeV) in the context of a Higssless Standard Model (SM), i.e. a nonlinear SU(2)_L \times U(1)_Y ... More
Axion star collisions with black holes and neutron stars in full 3D numerical relativityAug 14 2018Axions are a potential dark matter candidate, which may condense and form self gravitating compact objects, called axion stars (ASs). In this work, we study for the first time head-on collisions of relativistic ASs with black holes (BHs) and neutron stars ... More
Strategy Derivation for Small Progress MeasuresJul 08 2014May 19 2015Small Progress Measures is one of the most efficient parity game solving algorithms. The original algorithm provides the full solution (winning regions and strategies) in $O(dm \cdot (n/\lceil d / 2 \rceil)^{\lceil d/2 \rceil})$ time, and requires a re-run ... More
The Multiplicity Conjecture in low codimensionsOct 22 2004We establish the multiplicity conjecture of Herzog, Huneke, and Srinivasan about the multiplicity of graded Cohen-Macaulay algebras over a field, for codimension two algebras and for Gorenstein algebras of codimension three. In fact, we prove stronger ... More
A Model of Strong Flavor Dynamics for the Top QuarkMar 19 1996We discuss a model in which the third generation fermions undergo a different $SU(2)$ weak interaction from the first two generation fermions. In general, a flavor changing neutral current interaction is expected. Constrained by the precision low energy ... More
Improvement in Small Progress MeasuresSep 24 2015Small Progress Measures is one of the classical parity game solving algorithms. For games with n vertices, m edges and d different priorities, the original algorithm computes the winning regions and a winning strategy for one of the players in O(dm.(n/floor(d/2))^floor(d/2)) ... More
Zielonka's Recursive Algorithm: dull, weak and solitaire games and tighter boundsJul 17 2013Dull, weak and nested solitaire games are important classes of parity games, capturing, among others, alternation-free mu-calculus and ECTL* model checking problems. These classes can be solved in polynomial time using dedicated algorithms. We investigate ... More
Single Top Production as a Window to Physics Beyond the Standard ModelJul 26 2000Oct 17 2000Production of single top quarks at a high energy hadron collider is studied as a means to identify physics beyond the standard model related to the electroweak symmetry breaking. The sensitivity of the $s$-channel $W^*$ mode, the $t$-channel $W$-gluon ... More
Diffusion imaging with stimulated echoes: signal models and experiment designMay 31 2013Jun 12 2013Purpose: Stimulated echo acquisition mode (STEAM) diffusion MRI can be advantageous over pulsed-gradient spin-echo (PGSE) for diffusion times that are long compared to $\ttwo$. It is important therefore for biomedical diffusion imaging applications at ... More
Expressiveness and Completeness in AbstractionAug 14 2012We study two notions of expressiveness, which have appeared in abstraction theory for model checking, and find them incomparable in general. In particular, we show that according to the most widely used notion, the class of Kripke Modal Transition Systems ... More
Towards the multivariate simplotope spline: continuity conditions in a class of mixed simplotopic gridsFeb 03 2016Smooth joins of simplex Bernstein-B\'ezier polynomials have been studied extensively in the past. In this paper a new method is proposed to define continuity conditions for tensor-product Bernstein polynomials on a class of mixed grids that meets certain ... More
Improved Static Analysis of Parameterised Boolean Equation Systems using Control Flow ReconstructionApr 24 2013Apr 27 2014We present a sound static analysis technique for fighting the combinatorial explosion of parameterised Boolean equation systems (PBESs). These essentially are systems of mutually recursive fixed point equations ranging over first-order logic formulae. ... More
Higher order corrections for anisotropic bootstrap percolationNov 10 2016Oct 09 2017We study the critical probability for the metastable phase transition of the two-dimensional anisotropic bootstrap percolation model with $(1,2)$-neighbourhood and threshold $r = 3$. The first order asymptotics for the critical probability were recently ... More
The Search for Anomalous W^+ W^- t \bar{t} Couplings at the LCJan 22 2001We study production of t \bar{t} via W^+ W^--fusion, including the relevant backgrounds at the proposed Linear Collider (an e^+ e^- collider with \sqrt{S} = 1.5 TeV) in the context of a Higssless Standard Model (HSM), i.e. a nonlinear SU(2)_L \times U(1)_Y ... More
Photoionization calculations of the radiation force due to spectral lines in AGNsDec 05 2018One of the main physical mechanisms that could drive mass outflows in AGNs is radiation pressure on spectral lines. Although this mechanism is conceptually straightforward to understand, the actual magnitude of the radiation force is challenging to compute ... More
Specifying RobustnessSep 14 2013This paper proposes a new logic RoCTL* to model robustness in concurrent systems. RoCTL* extends CTL* with the addition of Obligatory and Robustly operators, which quantify over failure-free paths and paths with one more failure respectively. We present ... More
Opaque Branes in Warped BackgroundsDec 20 2002Mar 05 2003We examine localized kinetic terms for gauge fields which can propagate into compact, warped extra dimensions. We show that these terms can have a relevant impact on the values of the Kaluza-Klein (KK) gauge field masses, wave functions, and couplings ... More
Symmetry Breaking with Polynomial DelayDec 27 2010A conservative class of constraint satisfaction problems CSPs is a class for which membership is preserved under arbitrary domain reductions. Many well-known tractable classes of CSPs are conservative. It is well known that lexleader constraints may significantly ... More
HoPP: Robust and Resilient Publish-Subscribe for an Information-Centric Internet of ThingsJan 11 2018This paper revisits NDN deployment in the IoT with a special focus on the interaction of sensors and actuators. Such scenarios require high responsiveness and limited control state at the constrained nodes. We argue that the NDN request-response pattern ... More
ICNLoWPAN -- Named-Data Networking for Low Power IoT NetworksDec 17 2018Information Centric Networking is considered a promising communication technology for the constrained IoT, but NDN was designed only for standard network infrastructure. In this paper, we design and evaluate an NDN convergence layer for low power lossy ... More
On the edge energy of grapheneDec 12 2017Surface/edge energy is typically modeled as a continuous function of orientation, $\gamma({\bf n})$. We put forward a simple geometric argument that suggests this picture is inadequate for crystals with a non-Bravais lattice structure. In the case of ... More
Branes and Orbifolds are OpaqueJul 03 2002Nov 25 2002We examine localized kinetic terms for gauge fields which can propagate into compact extra dimensions. We find that such terms are generated by radiative corrections in both theories with matter fields confined to branes and in theories imposing orbifold ... More
The mildly nonlinear imprint of structure on the CMBDec 03 1999Dec 05 1999I outline some nonperturbative relativistic effects that arise from gravitational corrections to the Boltzmann equations. These may be important for the study of CMB temperature anisotropies, particularly their interpretation. These terms are not included ... More
The Labyrinth of Quantum LogicFeb 06 2018Quantum mechanics predicts many surprising phenomena, including the two-slit interference of electrons. It has often been claimed that these phenomena cannot be understood in classical terms. But the meaning of "classical" is often not precisely specified. ... More
Homological properties of bigraded algebrasNov 24 2000Sep 23 2001We study the x- and y-regularity of a bigraded K-algebra R. These notions are used to study asymptotic properties of certain finitely generated bigraded modules. As an application we get for any equigenerated graded ideal I upper bounds for the number ... More
Evolutionary Innovations and Where to Find Them: Routes to Open-Ended Evolution in Natural and Artificial SystemsJun 05 2018Feb 21 2019This paper presents a high-level conceptual framework to help orient the discussion and implementation of open-endedness in evolutionary systems. Drawing upon earlier work by Banzhaf et al., three different kinds of open-endedness are identified: exploratory, ... More
The structure of low-complexity Gibbs measures on product spacesOct 16 2018Mar 04 2019Let $K_1$, $\dots$, $K_n$ be bounded, complete, separable metric spaces. Let $\lambda_i$ be a Borel probability measure on $K_i$ for each $i$. Let $f:\prod_i K_i \to \mathbb{R}$ be a bounded and continuous potential function, and let $$\mu(d \mathbf{x})\ ... More
Discrete Hashimoto surfaces and a doubly discrete smokering flowJul 25 2000B\"acklund transformations for smooth and ``space discrete'' Hashimoto surfaces are discussed and a geometric interpretation is given. It is shown that the complex curvature of a discrete space curve evolves with the discrete nonlinear Schr\"odinger equation ... More
Norm convergence of continuous-time polynomial multiple ergodic averagesMar 01 2011Jul 01 2016For a jointly measurable probability-preserving action $\tau:\mathbb{R}^D\curvearrowright (X,\mu)$ and a tuple of polynomial maps $p_i:\mathbb{R}\to \mathbb{R}^D$, $i=1,2,...,k$, the multiple ergodic averages \[ \frac{1}{T}\int_0^T (f_1\circ \tau^{p_1(t)})(f_2\circ ... More
Behaviour of entropy under bounded and integrable orbit equivalenceApr 04 2016Nov 07 2016Let $G$ and $H$ be infinite finitely generated amenable groups. This paper studies two notions of equivalence between actions of such groups on standard Borel probability spaces. They are defined as stable orbit equivalences in which the associated cocycles ... More
RectangularityAug 08 2011We introduce a condition on arrays in some way maximally distinct from Latin square condition, as well as some other conditions on algebras, graphs and $0,1$-matrices. We show that these are essentially the same structures, generalising a similar collection ... More
The geometry of model spaces for probability-preserving actions of sofic groupsDec 04 2015Jun 06 2016Bowen's notion of sofic entropy is a powerful invariant for classifying probability-preserving actions of sofic groups. It can be defined in terms of the covering numbers of certain metric spaces associated to such an action, the `model spaces'. The metric ... More
Radio detection of cosmic rays with the Auger Engineering Radio ArrayMay 13 2019The Auger Engineering Radio Array (AERA) complements the Pierre Auger Observatory with 150 radio-antenna stations measuring in the frequency range from 30 to 80 MHz. With an instrumented area of 17 km$^2$, the array constitutes the largest cosmic-ray ... More
Rational group ring elements with kernels having irrational dimensionSep 12 2009Mar 12 2013We prove that there are examples of finitely generated groups G together with group ring elements Q \in \bbQ G for which the von Neumann dimension \dim_{LG}\ker Q is irrational, so (in conjunction with other known results) answering a question of Atiyah. ... More
Uniform stability of linear evolution equations, with applications to parallel transportsFeb 12 2015I prove the bistability of linear evolution equations $x' = A(t)x$ in a Banach space $E$, where the operator-valued function $A$ is of the form $A(t) = f'(t)G(t,f(t))$ for a binary operator-valued function $G$ and a scalar function $f$. The constant that ... More
A Geometric Embedding for Standard Analytic ModulesMar 28 2005Jun 11 2007In this manuscript we make a general study of the representations realized, for a reductive Lie group of Harish-Chandra class, on the compactly supported sheaf cohomology groups of an irreducible finite-rank polarized homogeneous vector bundle defined ... More
Higgs in Space!Nov 30 2009Mar 18 2010We consider the possibility that the Higgs can be produced in dark matter annihilations, appearing as a line in the spectrum of gamma rays at an energy determined by the masses of the WIMP and the Higgs itself. We argue that this phenomenon occurs generally ... More
Transition Energy in Strong and Weak Confinement of Type-I Spherical Core-shell Quantum DotsNov 16 2018In this paper, we present a mathematical approach in estimating transition energy of type-I core-shell quantum dots (CSQDs) in strong and weak confinement of charge carriers within the core materials. We will do this by using effective-mass approximation ... More
Unconventional Multiferroicity in Cupric OxideJan 22 2011The magnetic phase transitions reported below 230 K in cupric oxide are analyzed theoretically at the macroscopic and microscopic levels. The incommensurate multiferroic and lock-in commensurate phases are shown to realize an inverted sequence of symmetry-breaking ... More
Measuring, Understanding, and Classifying News Media Sympathy on Twitter after Crisis EventsJan 16 2018Mar 15 2018This paper investigates bias in coverage between Western and Arab media on Twitter after the November 2015 Beirut and Paris terror attacks. Using two Twitter datasets covering each attack, we investigate how Western and Arab media differed in coverage ... More
Higgs Boson with Large Bottom Yukawa Coupling at Tevatron and LHCFeb 10 1998Apr 09 1998We study the discovery reach of the Tevatron and the LHC for detecting a Higgs boson (h), predicted in composite models of the electroweak symmetry breaking or in supersymmetric theories, with an enhanced b-quark Yukawa coupling via p \bar{p} / p p \to ... More
Maverick dark matter at collidersFeb 22 2010Aug 23 2010Assuming that dark matter is a weakly interacting massive particle (WIMP) species X produced in the early Universe as a cold thermal relic, we study the collider signal of pp or ppbar -> XXbar + jets and its distinguishability from standard-model background ... More
The WIMP Forest: Indirect Detection of a Chiral SquareApr 08 2009The spectrum of photons arising from WIMP annihilation carries a detailed imprint of the structure of the dark sector. In particular, loop-level annihilations into a photon and another boson can in principle lead to a series of lines (a WIMP forest) at ... More
Gamma Rays from Top-Mediated Dark Matter AnnihilationsMar 19 2013Nov 04 2013Lines in the energy spectrum of gamma rays are a fascinating experimental signal, which are often considered "smoking gun" evidence of dark matter annihilation. The current generation of gamma ray observatories are currently closing in on parameter space ... More
Linearized inverse scattering based on seismic Reverse Time MigrationDec 20 2010Jan 21 2011In this paper we study the linearized inverse problem associated with imaging of reflection seismic data. We introduce an inverse scattering transform derived from reverse-time migration (RTM). In the process, the explicit evaluation of the so-called ... More
Exploring the Limits of Complexity: A Survey of Empirical Studies on Graph VisualisationSep 02 2018For decades, researchers in information visualisation and graph drawing have focused on developing techniques for the layout and display of very large and complex networks. Experiments involving human participants have also explored the readability of ... More
Towards a Noether-like conservation law theorem for one dimensional reversible cellular automataDec 01 2003Evidence and results suggesting that a Noether--like theorem for conservation laws in 1D RCA can be obtained. Unlike Noether's theorem, the connection here is to the maximal congruences rather than the automorphisms of the local dynamics. We take the ... More
Counting Cliques in Finite Distant GraphsDec 23 2016We state and prove some counting formulas relating to cliques in the distant graphs of projective lines over finite rings. As a preliminary to this, we prove a decomposition theorem for the graphs in terms of the direct-product decomposition of their ... More
The ECMWF Ensemble Prediction System: Looking Back (more than) 25 Years and Projecting Forward 25 YearsMar 16 2018This paper has been written to mark 25 years of operational medium-range ensemble forecasting. The origins of the ECMWF Ensemble Prediction System are outlined, including the development of the precursor real-time Met Office monthly ensemble forecast ... More
Modern Python at the Large Synoptic Survey TelescopeDec 01 2017The LSST software systems make extensive use of Python, with almost all of it initially being developed solely in Python 2. Since LSST will be commissioned when Python 2 is end-of-lifed it is critical that we have all our code support Python 3 before ... More
Time Symmetric Quantum Theory Without RetrocausalityJul 24 2017In their recent paper "Is a Time Symmetric Interpretation of Quantum Theory Possible Without Retrocausality?", Matthew Leifer and Matthew Pusey argue that the answer to their title question is "no". Unfortunately, the central proof offered in the paper ... More
Gluing and deformations of asymptotically cylindrical special LagrangiansSep 27 2017We study gluings of asymptotically cylindrical special Lagrangian submanifolds in asymptotically cylindrical Calabi--Yau manifolds. We prove both that there is a well-defined gluing map, and, after reviewing the deformation theory for special Lagrangians, ... More
Contrastive Explanation: A Structural-Model ApproachNov 07 2018The topic of causal explanation in artificial intelligence has gathered interest in recent years as researchers and practitioners aim to increase trust and understanding of intelligent decision-making and action. While different sub-fields have looked ... More
Free Semialgebraic GeometryFeb 28 2019This is a survey article on the currently very active research area of free (=non-commutative) real algebra and geometry. We first review some of the important results from the commutative theory, and then explain similarities and differences as well ... More
Comparing invariants of SK1Mar 08 2010Mar 18 2010In this text, we compare several invariants of the reduced Whitehead group SK1 of a central simple algebra. For biquaternion algebras, we compare a generalised invariant of Suslin as constructed by the author in a previous article to an invariant introduced ... More
Observable Equivalence between General Relativity and Shape DynamicsMar 29 2012In this conceptual paper we construct a local version of Shape Dynamics that is equivalent to General Relativity in the sense that the algebras of Dirac observables weakly coincide. This allows us to identify Shape Dynamics observables with General Relativity ... More
Shape DynamicsAug 26 2011General Relativity can be reformulated as a geometrodynamical theory, called Shape Dynamics, that is not based on spacetime (in particular refoliation) symmetry but on spatial diffeomorphism and local spatial conformal symmetry. This leads to a constraint ... More
Reduction of a Quantum TheoryDec 21 2006This paper serves as a preparation of work that focuses on extracting cosmological sectors from Loop Quantum Gravity. We start with studying the extraction of subsystems from classical systems. A classical Hamiltonian system can be reduced to a subsystem ... More
Deducing the Density Hales-Jewett Theorem from an infinitary removal lemmaMar 09 2009Apr 19 2011We offer a new proof of Furstenberg and Katznelson's density version of the Hales-Jewett Theorem: For any $\delta > 0$ there is some $N_0 \geq 1$ such that whenever $A \subseteq [k]^N$ with $N \geq N_0$ and $|A|\geq \delta k^N$, $A$ contains a \textbf{combinatorial ... More
Multiple recurrence and the structure of probability-preserving systemsJun 02 2010Jun 08 2010In 1975 Szemer\'edi proved the long-standing conjecture of Erd\H{o}s and Tur\'an that any subset of $\bbZ$ having positive upper Banach density contains arbitrarily long arithmetic progressions. Szemer\'edi's proof was entirely combinatorial, but two ... More
Who discovered positron annihilation?Sep 13 2018In the early 1930s, the positron, pair production, and, at last, positron annihilation were discovered. Over the years, several scientists have been credited with the discovery of the annihilation radiation. Commonly, Thibaud and Joliot have received ... More
An asymptotic equipartition property for measures on model spacesJan 30 2017Sep 18 2018Let $G$ be a sofic group, and let $\Sigma = (\sigma_n)_{n\geq 1}$ be a sofic approximation to it. For a probability-preserving $G$-system, a variant of the sofic entropy relative to $\Sigma$ has recently been defined in terms of sequences of measures ... More
Equidistribution of joinings under off-diagonal polynomial flows of nilpotent Lie groupsMay 27 2011Jul 01 2016Let $G$ be a connected nilpotent Lie group. Given probability-preserving $G$-actions $(X_i,\Sigma_i,\mu_i,u_i)$, $i=0,1,...,k$, and also polynomial maps $\phi_i:\mathbb{R}\to G$, $i=1,...,k$, we consider the trajectory of a joining $\lambda$ of the systems ... More
An alternative ending to "Pleasant extensions retaining algebraic structure''Oct 06 2009May 24 2010The culmination of the papers (arXiv:0905.0518, arXiv:0910.0909) was a proof of the norm convergence in $L^2(\mu)$ of the quadratic nonconventional ergodic averages \frac{1}{N}\sum_{n=1}^N(f_1\circ T_1^{n^2})(f_2\circ T_1^{n^2}T_2^n)\quad\quad f_1,f_2\in ... More
A short extension of two of Spira's resultsDec 05 2013Oct 17 2014Two inequalities concerning the symmetry of the zeta-function and the Ramanujan $\tau$-function are improved through the use of some elementary considerations.
On semidefinite representations of non-closed setsJul 16 2009Dec 17 2009Spectrahedra are sets defined by linear matrix inequalities. Projections of spectrahedra are called semidefinitely representable sets. Both kinds of sets are of practical use in polynomial optimization, since they occur as feasible sets in semidefinite ... More
Ajtai-Szemerédi Theorems over quasirandom groupsMar 30 2015May 19 2015Two versions of the Ajtai-Szemer\'edi Theorem are considered in the Cartesian square of a finite non-Abelian group $G$. In case $G$ is sufficiently quasirandom, we obtain strong forms of both versions: if $E \subseteq G\times G$ is fairly dense, then ... More
A Discussion on Solving Partial Differential Equations using Neural NetworksApr 15 2019Can neural networks learn to solve partial differential equations (PDEs)? We investigate this question for two (systems of) PDEs, namely, the Poisson equation and the steady Navier--Stokes equations. The contributions of this paper are five-fold. (1) ... More
The one-arm exponent for mean-field long-range percolationNov 11 2014Consider a long-range percolation model on $\mathbb{Z}^d$ where the probability that an edge $\{x,y\} \in \mathbb{Z}^d \times \mathbb{Z}^d$ is open is proportional to $\|x-y\|_2^{-d-\alpha}$ for some $\alpha >0$ and where $d > 3 \min\{2,\alpha\}$. We ... More
Strictly elliptic operators with Dirichlet boundary conditions on spaces of continuous functions on manifoldsAug 20 2018Jan 14 2019We study strictly elliptic differential operators with Dirichlet boundary conditions on the space $\mathrm{C}(\overline{M})$ of continuous functions on a compact, Riemannian manifold $\overline{M}$ with boundary and prove sectoriality with optimal angle ... More
Plethysm and fast matrix multiplicationOct 02 2017Apr 09 2018Motivated by the symmetric version of matrix multiplication we study the plethysm $S^k(\mathfrak{sl}_n)$ of the adjoint representation $\mathfrak{sl}_n$ of the Lie group $SL_n$. In particular, we describe the decomposition of this representation into ... More
The n-homology of representationsApr 01 2008Jun 23 2008This is an expository article, written for a special edition of the journal of the UMA (Union Matematica Argentina) commemorating the mathematician Misha Cotlar. The article gives an introduction to the n-homology groups and surveys some developments, ... More
Particle Physics Implications and Constraints on Dark Matter Interpretations of the CDMS SignalMay 28 2013Nov 05 2013Recently the CDMS collaboration has reported an excess of events in the signal region of a search for dark matter scattering with Silicon nuclei. Three events on an expected background of 0.4 have a significance of about 2 sigma, and it is premature to ... More
Gamma-ray lines and One-Loop Continuum from s-channel Dark Matter AnnihilationsFeb 07 2013Nov 04 2013The era of indirect detection searches for dark matter has begun, with the sensitivities of gamma-ray detectors now approaching the parameter space relevant for weakly interacting massive particles. In particular, gamma ray lines would be smoking gun ... More
On 021-Avoiding Ascent SequencesJun 13 2012Jun 21 2012Ascent sequences were introduced by Bousquet-M\'{e}lou, Claesson, Dukes and Kitaev in their study of $(\bf{2+2})$-free posets. An ascent sequence of length $n$ is a nonnegative integer sequence $x=x_{1}x_{2}... x_{n}$ such that $x_{1}=0$ and $x_{i}\leq ... More
NDN, CoAP, and MQTT: A Comparative Measurement Study in the IoTJun 05 2018Sep 28 2018This paper takes a comprehensive view on the protocol stacks that are under debate for a future Internet of Things (IoT). It addresses the holistic question of which solution is beneficial for common IoT use cases. We deploy NDN and the two popular IP-based ... More
Flavour physics in the LHC eraJun 19 2013Jul 26 2014These lectures give a topical review of heavy flavour physics, in particular \CP violation and rare decays, from an experimental point of view. They describe the ongoing motivation to study heavy flavour physics in the LHC era, the current status of the ... More
Behaviour of entropy under bounded and integrable orbit equivalenceApr 04 2016Jun 08 2016Let $G$ and $H$ be infinite finitely generated amenable groups. This paper studies two notions of equivalence between actions of such groups on standard Borel probability spaces. They are defined as stable orbit equivalences in which the associated cocycles ... More
Distribution and Generalized Center in Planar NearringsJul 05 2016Planar nearrings play an important role in nearring theory, both from the structural side as being close to generalised nearfields, as well as from an applications perspective, in geometry and designs. We investigate the distributive elements of planar ... More
Crazy Sequential Representations of Numbers for Small BasesOct 11 2018Throughout history, recreational mathematics has always played a prominent role in advancing research. Following in this tradition, in this paper we extend some recent work with crazy sequential representations of numbers- equations made of sequences ... More
Models of curves over DVRsJun 29 2018Let C be a smooth projective curve over a discretely valued field K, defined by an affine equation f(x,y)=0. We construct a model of C over the ring of integers of K using a toroidal embedding associated to the Newton polygon of f. We show that under ... More
Computational Power and the Social Impact of Artificial IntelligenceMar 23 2018Machine learning is a computational process. To that end, it is inextricably tied to computational power - the tangible material of chips and semiconductors that the algorithms of machine intelligence operate on. Most obviously, computational power and ... More
Lectures on twistor theoryDec 06 2017Jan 15 2018Broadly speaking, twistor theory is a framework for encoding physical information on space-time as geometric data on a complex projective space, known as a twistor space. The relationship between space-time and twistor space is non-local and has some ... More
Combining Representation Learning with Logic for Language ProcessingDec 27 2017The current state-of-the-art in many natural language processing and automated knowledge base completion tasks is held by representation learning methods which learn distributed vector representations of symbols via gradient-based optimization. They require ... More
Non-Nudgable Subgroups of PermutationsJun 21 2017Jul 17 2017Motivated by a problem from behavioral economics, we study subgroups of permutation groups that have a certain strong symmetry. Given a fixed permutation, consider the set of all permutations with disjoint inversion sets. The group is called non-nudgable, ... More
(Information) Paradox LostMay 06 2017Since Stephen Hawking's original 1975 paper on black hole evaporation, there has been a consensus that the problem of "loss of information" is both deep and troubling. It is also thought that resolution of the problem may hold some conceptual keys to ... More
Porting the LSST Data Management Pipeline Software to Python 3Nov 02 2016The LSST data management science pipelines software consists of more than 100,000 lines of Python 2 code. LSST operations will begin after support for Python 2 has been dropped by the Python community in 2020, and we must therefore plan to migrate the ... More
Notes on the Parity ConjectureSep 27 2010Jan 17 2012This is an expository article, based on a lecture course given at CRM Barcelona in December 2009. The purpose of these notes is to prove, in a reasonably self-contained way, that finiteness of the Tate-Shafarevich group implies the parity conjecture for ... More
Ranks of elliptic curves in cubic extensionsOct 25 2005For an elliptic curve E over a number field K, we prove that the algebraic rank of E goes up in infinitely many extensions of K obtained by adjoining a cube root of an element of K. As an example, we briefly discuss E=X_1(11) over Q, and how the result ... More
Quotients of functors of Artin ringsNov 21 2005In infinitesimal deformation theory, a classical criterion due to Schlessinger gives an intrinsic characterisation of functors that are pro-representable, and more generally, of the ones that have a hull. Our result is that in this setting the question ... More
Zero-sets of near-symplectic formsJan 13 2006Jan 15 2007We give elementary proofs of two `folklore' assertions about near-symplectic forms on four-manifolds: that any such form can be modified, by an evolutionary process taking place within a finite set of balls, so as to have a prescribed positive number ... More
Measure concentration and the weak Pinsker propertyApr 30 2017Feb 16 2018Let $(X,\mu)$ be a standard probability space. An automorphism $T$ of $(X,\mu)$ has the weak Pinsker property if for every $\varepsilon > 0$ it has a splitting into a direct product of a Bernoulli shift and an automorphism of entropy less than $\varepsilon$. ... More
n-Dimensional Optical Orthogonal Codes, Bounds and Optimal ConstructionsApr 19 2018We generalized to higher dimensions the notions of optical orthogonal codes. We establish uper bounds on the capacity of general $ n $-dimensional OOCs, and on specific types of ideal codes (codes with zero off-peak autocorrelation). The bounds are based ... More