Results for "Lars Buesing"
total 2519took 0.13s
Credit Assignment Techniques in Stochastic Computation GraphsJan 07 2019Stochastic computation graphs (SCGs) provide a formalism to represent structured optimization problems arising in artificial intelligence, including supervised, unsupervised, and reinforcement learning. Previous work has shown that an unbiased estimator ... More Temporal Difference Variational Auto-EncoderJun 08 2018Jan 02 2019To act and plan in complex environments, we posit that agents should have a mental simulator of the world with three characteristics: (a) it should build an abstract state representing the condition of the world; (b) it should form a belief which represents ... More Black box variational inference for state space modelsNov 23 2015Latent variable time-series models are among the most heavily used tools from machine learning and applied statistics. These models have the advantage of learning latent structure both from noisy observations and from the temporal ordering in the data, ... More Learning model-based planning from scratchJul 19 2017Conventional wisdom holds that model-based planning is a powerful approach to sequential decision-making. It is often very challenging in practice, however, because while a model can be used to evaluate a plan, it does not prescribe how to construct a ... More Imagination-Augmented Agents for Deep Reinforcement LearningJul 19 2017Feb 14 2018We introduce Imagination-Augmented Agents (I2As), a novel architecture for deep reinforcement learning combining model-free and model-based aspects. In contrast to most existing model-based reinforcement learning and planning methods, which prescribe ... More Woulda, Coulda, Shoulda: Counterfactually-Guided Policy SearchNov 15 2018Learning policies on data synthesized by models can in principle quench the thirst of reinforcement learning algorithms for large amounts of real experience, which is often costly to acquire. However, simulating plausible experience de novo is a hard ... More Geometric Analysis and General RelativityDec 23 2005This article discusses methods of geometric analysis in general relativity, with special focus on the role of "critical surfaces" such as minimal surfaces, marginal surface, maximal surfaces and null surfaces. Maximal supersymmetry and exceptional groupsJun 08 2010The article is a tribute to my old mentor, collaborator and friend Murray Gell-Mann. In it I describe work by Pierre Ramond, Sung-Soo Kim and myself where we describe the N = 8 Supergravity in the light-cone formalism. We show how the Cremmer-Julia E7(7) ... More Recent multi-wavelength campaigns in the Fermi-GST eraJul 02 2010Since 2008 the Fermi/LAT instrument has delivered highly time-resolved gamma-ray spectra and detailed variability curves for a steadily increasing number of AGN. For detailed AGN studies the Fermi/LAT data have to be combined with, and accompanied by, ... More Algorithm Selection for Combinatorial Search Problems: A SurveyOct 30 2012The Algorithm Selection Problem is concerned with selecting the best algorithm to solve a given problem on a case-by-case basis. It has become especially relevant in the last decade, as researchers are increasingly investigating how to identify the most ... More The MSSM with large tan(beta) beyond the decoupling limitOct 02 2009For large values of tan(beta) interesting effects arise in the MSSM due to the enhancement of down-quark self-energies. These effects are well-studied within the decoupling limit, i.e. in the limit of supersymmetric masses far above the electroweak scale. ... More Algebraic approach to solve $t\bar{t}$ dilepton equationsOct 07 2005Jun 18 2011The set of non-linear equations describing the Standard Model kinematics of the top quark antiqark production system in the dilepton decay channel has at most a four-fold ambiguity due to two not fully reconstructed neutrinos. Its most precise solution ... More Searches for New Phenomena at the LHCJun 26 2012Searches for physics beyond the Standard Model (SM) with the CMS and ATLAS experiments in pp collisions at a centre of mass energy of sqrt(s)=7 TeV at the LHC are presented. The discussed results are based on data taken in 2011, making use of integrated ... More Analytical solution of ttbar dilepton equationsMar 01 2006Jun 18 2011The top quark antiquark production system in the dilepton decay channel is described by a set of equations which is nonlinear in the unknown neutrino momenta. Its most precise and least time consuming solution is of major importance for measurements of ... More CDF and D0 top quark cross section measurementsOct 13 2004Nov 03 2004Preliminary results of ttbar cross section measurements and single top exclusion limits of the Tevatron experiments CDF and D0 are presented. The different measurements are based on a dataset between 140 and 200 inverse pb corresponding to a data taking ... More The D0 Silicon Track TriggerSep 01 2004The Level-2 Silicon Track Trigger preprocessor (L2 STT) of the D0 detector in Run II is described. It performs a precise reconstruction of charged particle tracks in the Central Fiber Tracker (CFT) and the Silicon Microstrip Tracker (SMT). Events with ... More Ideal depth of QF extensionsDec 08 2010A minimum depth d^I(S --> R) is assigned to a ring homomorphism S --> R and a R-R-bimodule I. The recent notion of depth of a subring d(S,R)in a paper by Boltje-Danz-Kuelshammer is recovered when I = R and S --> R is the inclusion mapping. Ideal depth ... More The big de Rham-Witt complexJun 16 2010Dec 07 2014This paper gives a new and direct construction of the multi-prime big de Rham-Witt complex which is defined for every commutative and unital ring; the original construction by the author and Madsen relied on the adjoint functor theorem and accordingly ... More An approach to quasi-Hopf algebras via Frobenius coordinatesAug 18 2004We study quasi-Hopf algebras and their subobjects over certain commutative rings from the point of view of Frobenius algebras. We introduce a type of Radford formula involving an anti-automorphism and the Nakayama automorphism of a Frobenius algebra, ... More Normal Hopf subalgebras, depth two and Galois extensionsNov 06 2004Apr 06 2005Let $S$ be the left $R$-bialgebroid of a depth two extension with centralizer $R$ as defined in math.QA/0108067. We show that the left endomorphism ring of depth two extension, not necessarily balanced, is a left $S$-Galois extension of $A^{\rm op}$. ... More Skew Hopf algebras, irreducible extensions and the pi-methodJan 15 2007Dec 28 2007To a depth two extension A | B, we associate the dual bialgebroids S := \End {}_BA_B and T := (A \o_B A)^B over the centralizer R=C_A(B). In the set-up where R is a subalgebra of B, which is quite common, two nondegenerate pairings of S and T will define ... More On the Whitehead spectrum of the circleOct 15 2007May 22 2008The seminal work of Waldhausen, Farrell and Jones, Igusa, and Weiss and Williams shows that the homotopy groups in low degrees of the space of homeomorphisms of a closed Riemannian manifold of negative sectional curvature can be expressed as a functor ... More The trapped regionJan 17 2009Jan 20 2009I will discuss some recent results on marginally outer trapped surfaces, apparent horizons, and the trapped region. A couple of applications of the results developed for marginally outer trapped surfaces to coalescence of black holes and to the characterization ... More On the relation between mathematical and numerical relativityJul 17 2006The large scale binary black hole effort in numerical relativity has led to an increasing distinction between numerical and mathematical relativity. This note discusses this situation and gives some examples of succesful interactions between numerical ... More The global existence problem in general relativityNov 09 1999Apr 28 2006We survey some known facts and open questions concerning the global properties of 3+1 dimensional spacetimes containing a compact Cauchy surface. We consider spacetimes with an $\ell$-dimensional Lie algebra of space-like Killing fields. For each $\ell ... More Gravitational Radiation and Rotation of Accreting Neutron StarsApr 29 1998Recent discoveries by the Rossi X-Ray Timing Explorer indicate that most of the rapidly accreting and weakly magnetic neutron stars in the Galaxy are rotating at spin frequencies greater than 250 Hz. Remarkably, they all rotate in a narrow range of frequencies. ... More The Angular Momentum of Accreting Neutron StarsJan 07 1998I review the rotation measurements of accreting neutron stars. Many of the highly magnetic accreting X-ray pulsars have been continuously observed with the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO) since ... More Thermonuclear Burning on Rapidly Accreting Neutron StarsSep 10 1997Neutron stars in mass-transferring binaries are accreting the hydrogen and helium rich matter from the surfaces of their companions. This article simply explains the physics associated with how that material eventually fuses to form heavier nuclei and ... More Cosmological models and stabilityOct 07 2013Principles in the form of heuristic guidelines or generally accepted dogma play an important role in the development of physical theories. In particular, philosophical considerations and principles figure prominently in the work of Albert Einstein. As ... More A Generic Framework for Diamond LemmasDec 07 2007This paper gives a generic form of the diamond lemma, which includes support for additive and topological structures of the base set, and which does not require any further structure (e.g. an associative multiplication operation) to be present. This result ... More Chern classes of tropical vector bundlesNov 15 2009We introduce tropical vector bundles, morphisms and rational sections of these bundles and define the pull-back of a tropical vector bundle and of a rational section along a morphism. Afterwards we use the bounded rational sections of a tropical vector ... More The tower of K-theory of truncated polynomial algebrasFeb 28 2007Aug 12 2007Let A a regular F_p-algebra. The relative K-groups K_q(A[x]/(x^m),(x)) and the Nil-groups Nil_q(A[x]/(x^m)) were evaluated earlier by the author and Madsen in terms of the big de Rham-Witt groups of the ring A. In this paper, we evaluate the maps of relative ... More A tower condition characterizing normalityOct 18 2013Jan 27 2014We define left relative H-separable tower of rings and continue a study of these begun by Sugano. It is proven that a progenerator extension has right depth two if and only if the ring extension together with its right endomorphism ring is a left relative ... More Depth three towers of rings and groupsMar 12 2007May 11 2007Depth three and finite depth are notions known for subfactors via diagrams and Frobenius extensions of rings via centralizers in endomorphism towers. From the point of view of depth two ring extensions, we provide a clear definition of depth three for ... More A note on Galois theory for bialgebroidsJan 01 2005In this note we reduce certain proofs in \cite{KS, Karl, AMA} to depth two quasibases from one side only. This minimalistic approach leads to a characterization of Galois extensions for finite projective bialgebroids without the Frobenius extension property: ... More Uniquely separable extensionsAug 14 2018The separability tensor element of a separable extension of noncommutative rings is an idempotent when viewed in the correct endomorphism ring; so one speaks of a separability idempotent, as one usually does for separable algebras. It is proven that this ... More Dirichlet-to-Robin Operators via Composition SemigroupsSep 06 2017We show well-posedness for an evolution problem associated with the Dirichlet-to-Robin operator for certain Robin boundary data. Moreover, it turns out that the semigroup generated by the Dirichlet-to-Robin operator is closely related to a weighted semigroup ... More Intersections of Class FieldsSep 04 2017Nov 27 2017Using class field theory, we prove a restriction on the intersection of the maximal abelian extensions associated with different number fields. This restriction is then used to improve a result of Rosen and Silverman about the linear independence of Heegner ... More A Homogeneous Function Constant along the Leaves of a FoliationJul 03 2018Given a smooth foliation by complex curves (locally around a point $x\in\mathbb{C}^2\setminus\{0\}$) which is "compatible" with the foliation by spheres centered at the origin, we construct a smooth real-valued function $g$ in a neighborhood of said point, ... More A Parameter Version of Forstnerič's Splitting LemmaFeb 05 2018We construct solution operators to the $\overline{\partial}$-equation that depend continuously on the domain. This is applied to derive a parameter version of Forstneri\v{c}'s splitting lemma: If both the maps and the domains they are defined on vary ... More Separable equivalence of rings and symmetric algebrasOct 25 2017Nov 04 2018We continue a study of separable equivalence from Hokkaido Mathematical Journal 24 (1995), 527-549. We prove that symmetric separable equivalent rings $A$ and $B$ are linked by a Frobenius bimodule ${}_AP_B$ such that $A$ is $P$-separable over $B$. Separably ... More Construction of hyperboloidal initial dataMay 18 2002I describe the conformal method for constructing solutions of the hyperboloidal constraint equations as well as the conditions needed on the free data in order to have regularity up to boundary for the solutions to the constraint equations. A brief discussion ... More Arresting Accretion Torques with Gravitational RadiationNov 30 2002Recent theoretical work has made it plausible for neutron stars (NSs) to lose angular momentum via gravitational radiation on long timescales (around Myrs) while actively accreting. The gravitational waves (GWs) can either be emitted via the excitation ... More Hot White Dwarf Donors in Ultracompact X-Ray BinariesAug 07 2002The discovery of two accreting millisecond X-ray pulsars in binaries with 43 minute orbital periods allows for a new probe of the donor's structure. For XTE J1751-305, only a hot white dwarf (WD) can fill the Roche Lobe. A cold He WD is a possible solution ... More Measuring NUMA effects with the STREAM benchmarkMar 16 2011Modern high-end machines feature multiple processor packages, each of which contains multiple independent cores and integrated memory controllers connected directly to dedicated physical RAM. These packages are connected via a shared bus, creating a system ... More Ranking Algorithms by PerformanceNov 18 2013A common way of doing algorithm selection is to train a machine learning model and predict the best algorithm from a portfolio to solve a particular problem. While this method has been highly successful, choosing only a single algorithm has inherent limitations ... More Saas-Fee Lecture Notes: Multi-messenger Astronomy and Dark MatterFeb 06 2012Feb 10 2012Notes of lectures given at the Saas-Fee School 2010 in Les Diablerets, Switzerland. These notes are of introductory nature and should be suitable for graduate students and postdocs wanting to learn the basics of astroparticle physics and cosmology, with ... More Higgs searches at TevatronJul 09 2007SM and MSSM Higgs Searches at the proton anti-proton collider Tevatron in Run II are presented. The performance of the collider and the two experiments D0 and CDF is shown. No deviation from SM background expectation and no MSSM Higgs signal has been ... More Odd H-depth and H-separable extensionsOct 06 2011Jun 26 2012A subring pair B < A has right depth 2n if the n+1'st relative Hochschild bar resolution group is isomorphic to a direct summand of a multiple of the n'th relative Hochschild bar resolution group as A-B-bimodules; depth 2n+1 if the same condition holds ... More Simplicial Hochschild cochains as an Amitsur complexNov 23 2007It is shown that the cochain complex of relative Hochschild A-valued cochains of a depth two extension A | B under cup product is isomorphic as a differential graded algebra with the Amitsur complex of the coring S = End {}_BA_B over the centralizer R ... More Interactive Simplifier Tracing and Debugging in IsabelleJun 02 2014The Isabelle proof assistant comes equipped with a very powerful tactic for term simplification. While tremendously useful, the results of simplifying a term do not always match the user's expectation: sometimes, the resulting term is not in the form ... More On the Zeta Function of Forms of Fermat EquationsJan 17 2003We study ``forms of the Fermat equation'' over an arbitrary field $k$, i.e. homogenous equations of degree $m$ in $n$ unknowns that can be transformed into the Fermat equation $X_1^m+...+X_n^m$ by a suitable linear change of variables over an algebraic ... More Hopf algebroids and Galois extensionsSep 07 2004To a finite Hopf-Galois extension $A | B$ we associate dual bialgebroids $S := \End_BA_B$ and $T := (A \o_B A)^B$ over the centralizer $R$ using the depth two theory in math.RA/0108067. First we extend results on the equivalence of certain properties ... More A Note on the Eigenvalues of the Google MatrixJan 15 2004The Google matrix is a positive, column-stochastic matrix that is used to compute the pagerank of all the web pages on the Internet: the eigenvector corresponding to the eigenvalue 1 is the pagerank vector. Due to its huge dimension, of the order of billions, ... More An action-free characterization of weak Hopf-Galois extensionsSep 29 2004Dec 11 2004We define comodule algebras and Galois extensions for actions of bialgebroids. Using just module conditions we characterize the Frobenius extensions that are Galois as depth two and right balanced extensions. As a corollary, we obtain characterizations ... More Depth three towers and Jacobson-Bourbaki correspondenceJun 08 2007We introduce a notion of depth three tower of three rings C < B < A as a useful generalization of depth two ring extension. If A = End B_C and B | C is a Frobenius extension, this also captures the notion of depth three for a Frobenius extension in math.RA/0107064 ... More The Endomorphism Ring Theorem for Galois and D2 extensionsMar 10 2005Apr 01 2005Let $S$ be the left bialgebroid $\End {}_BA_B$ over the centralizer $R$ of a right D2 algebra extension $A \| B$, which is to say that its tensor-square is isomorphic as $A$-$B$-bimodules to a direct summand of a finite direct sum of $A$ with itself. ... More Infinite index subalgebras of depth twoJul 14 2006Aug 17 2006An algebra extension $A \| B$ is right depth two in this paper if its tensor-square is $A$-$B$-isomorphic to a direct summand of any (not necessarily finite) direct sum of $A$ with itself. For example, normal subgroups of infinite groups, infinitely generated ... More Integrability of generalized pluriharmonic mapsFeb 11 2015In this paper we provide examples of maps from almost complex domains into pseudo-Riemannian symmetric targets, which are pluriharmonic and not integrable, i.e. do not admit an associated family. More precisely, for one class of examples the source has ... More Topological Hochschild homology and the Hasse-Weil zeta functionFeb 05 2016Sep 16 2017We consider the Tate cohomology of the circle group acting on the topological Hochschild homology of schemes. We show that in the case of a scheme smooth and proper over a finite field, this cohomology theory naturally gives rise to the cohomological ... More Algebra depth in tensor categoriesNov 07 2015Nov 27 2015Study of the quotient module of a finite-dimensional Hopf subalgebra pair in order to compute its depth yields a relative Maschke Theorem, in which semisimple extension is characterized as being separable, and is therefore an ordinary Frobenius extension. ... More Self-gravitating elastic bodiesJul 30 2014Extended objects in GR are often modelled using distributional solutions of the Einstein equations with point-like sources, or as the limit of infinitesimally small "test" objects. In this note, I will consider models of finite self-gravitating extended ... More The Bounded Height Conjecture for Semiabelian VarietiesMar 11 2017Mar 12 2019The Bounded Height Conjecture of Bombieri, Masser, and Zannier states that for any sufficiently generic algebraic subvariety of a semiabelian $\overline{\mathbb{Q}}$-variety $G$ there is an upper bound on the Weil height of the points contained in its ... More On Effective Degrees of Freedom in the Early UniverseSep 16 2016Jan 26 2017We explore the effective degrees of freedom in the early universe, from before the electroweak scale at a few femtoseconds after the Big Bang, until the last positrons disappeared a few minutes later. We first look at the established concepts of effective ... More Points of Small Height on Semiabelian VarietiesAug 02 2018Mar 14 2019The Equidistribution Conjecture is proved for general semiabelian varieties over number fields. Previously, this conjecture was only known in the special case of almost split semiabelian varieties through work of Chambert-Loir. The general case has remained ... More The 130 GeV Fingerprint of Right-Handed Neutrino Dark MatterAug 30 2012Sep 03 2012Recently, an interesting indication for a dark matter signal in the form of a narrow line, or maybe two lines and/or an internal bremsstrahlung feature, has been found in data from the Fermi-LAT satellite detector. As recent analyses have also shown that ... More Side Effects in Steering FragmentsSep 10 2011In this thesis I will give a formal definition of side effects. I will do so by modifying a system for modelling program instructions and program states, Quantified Dynamic Logic, to a system called DLAf (for Dynamic Logic with Assignments as Formulas), ... More Photon plus Jet Cross Sections at the TevatronApr 03 2008Photon plus jet production has been studied by the D0 and CDF experiments in Run II of the Fermilab Tevatron Collider at a center of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon plus jet, di-photon and photon plus b jet cross ... More CMS: Cosmic muons in simulation and measured dataJul 03 2011A dedicated cosmic muon Monte-Carlo event generator CMSCGEN has been developed for the CMS experiment. The simulation relies on parameterisations of the muon energy and the incidence angle, based on measured and simulated data of the cosmic muon flux. ... More