Results for "Katrin Mang"

total 669took 0.11s
A phase-field model for fractures in incompressible solidsJan 16 2019Within this work, we develop a phase-field description for simulating fractures in incompressible materials. Standard formulations are subject to volume-locking when the solid is (nearly) incompressible. We propose an approach that builds on a mixed form ... More
Grover search with pairs of trapped ionsFeb 23 2001The desired interference required for quantum computing may be modified by the wave function oscillations for the implementation of quantum algorithms[Phys.Rev.Lett.84(2000)1615]. To diminish such detrimental effect, we propose a scheme with trapped ion-pairs ... More
Quantum computing and communication with decoherence-free atomic statesNov 07 2001To resist decoherence from destroying the phase factor of qubit state, it is important to use decoherence-free states for processing, transmitting and storing quantum information in quantum computing and quantum communication. We propose a practical scheme ... More
Simultaneous intraportation of many quantum states within the quantum computing networkMar 13 2001A scheme is proposed for simultaneous intraportation of many unknown quantum states within a quantum computing network. It is shown that our scheme, much different from the teleportation in the strict sense, can be very similar to the original teleportation ... More
Series solution to the laser-ion interaction in a Raman-type configurationNov 07 2001The Raman interaction of a trapped ultracold ion with two travelling wave lasers is studied analytically with series solutions, in the absence of the rotating wave approximation (RWA) and the restriction of both the Lamb-Dicke limit and the weak excitation ... More
Complete solution of the Schrödinger equation for the time-dependent linear potentialMay 29 2001The complete solutions of the Schr\"odinger equation for a particle with time-dependent mass moving in a time-dependent linear potential are presented. One solution is based on the wave function of the plane wave, and the other is with the form of the ... More
Preparation of Schrödinger cat states with cold ions beyond the Lamb-Dicke limitMar 20 2001A scheme for preparing Schr\"odinger cat (SC) states is proposed beyond the Lamb-Dicke limit in a Raman-$\Lambda$-type configuration. It is shown that SC states can be obtained more efficiently with our scheme than with the former ones.
Continued fraction solution to the Raman interaction of a trapped ultracold ion with two traveling wave lasersDec 17 2000Raman interaction of a trapped ultracold ion with two traveling wave lasers has been used extensively in the ion trap experiments. We solve this interaction in the absence of the rotating wave approximation by a continued fraction, without considering ... More
Mesh adaptivity for quasi-static phase-field fractures based on a residual-type a posteriori error estimatorJun 11 2019In this work, we consider adaptive mesh refinement for a monolithic phase-field description for fractures in brittle materials. Our approach is based on an a posteriori error estimator for the phase-field variational inequality realizing the fracture ... More
Implementation of quantum gates and preparation of entangled states in cavity QED with cold trapped ionsDec 06 2001Jul 29 2002We propose a scheme to perform basic gates of quantum computing and prepare entangled states in a system with cold trapped ions located in a single mode optical cavity. General quantum computing can be made with both motional state of the trapped ion ... More
Factorization of Frieze PatternsSep 02 2018In 2017, Michael Cuntz gave a definition of reducibility of quiddity cycles of frieze patterns: It is reducible if it can be written as a sum of two other quiddity cycles. We discuss the commutativity and associativity of this sum operator for quiddity ... More
An inexact Newton-Krylov algorithm for constrained diffeomorphic image registrationAug 27 2014May 07 2015We propose numerical algorithms for solving large deformation diffeomorphic image registration problems. We formulate the nonrigid image registration problem as a problem of optimal control. This leads to an infinite-dimensional partial differential equation ... More
A Semi-Lagrangian two-level preconditioned Newton-Krylov solver for constrained diffeomorphic image registrationApr 07 2016We propose an efficient numerical algorithm for the solution of diffeomorphic image registration problems. We use an optimization formulation constrained by a partial differential equation (PDE), where the constraints are a scalar transport equation. ... More
Categories of Two-Colored Pair Partitions, Part II: Categories Indexed by SemigroupsJan 10 2019Within the framework of unitary easy quantum groups, we study an analogue of Brauer's Schur-Weyl approach to the representation theory of the orthogonal group. We consider concrete combinatorial categories whose morphisms are formed by partitions of finite ... More
Constrained $H^1$-regularization schemes for diffeomorphic image registrationMar 02 2015Sep 07 2016We propose regularization schemes for deformable registration and efficient algorithms for their numerical approximation. We treat image registration as a variational optimal control problem. The deformation map is parametrized by its velocity. Tikhonov ... More
Non-Hyperoctahedral Categories of Two-Colored Partitions, Part I: New CategoriesJul 26 2019Compact quantum groups can be studied by investigating their co-representation categories in analogy to the Schur-Weyl/Tannaka-Krein approach. For the special class of (unitary) "easy" quantum groups these categories arise from a combinatorial structure: ... More
Optimization Algorithms for Catching Data Manipulators in Power System Estimation LoopsAug 01 2016In this paper we develop a set of algorithms that can detect the identities of malicious data-manipulators in distributed optimization loops for estimating oscillation modes in large power system models. The problem is posed in terms of an averaging consensus ... More
Optimization Algorithms for Catching Data Manipulators in Power System Estimation LoopsAug 01 2016Mar 28 2017In this paper we develop a set of algorithms that can detect the identities of malicious data-manipulators in distributed optimization loops for estimating oscillation modes in large power system models. The estimation is posed in terms of a consensus ... More
A Lagrangian Gauss-Newton-Krylov Solver for Mass- and Intensity-Preserving Diffeomorphic Image RegistrationMar 13 2017Jul 12 2017We present an efficient solver for diffeomorphic image registration problems in the framework of Large Deformations Diffeomorphic Metric Mappings (LDDMM). We use an optimal control formulation, in which the velocity field of a hyperbolic PDE needs to ... More
A Semi-Lagrangian two-level preconditioned Newton-Krylov solver for constrained diffeomorphic image registrationApr 07 2016Feb 28 2018We propose an efficient numerical algorithm for the solution of diffeomorphic image registration problems. We use a variational formulation constrained by a partial differential equation (PDE), where the constraints are a scalar transport equation. We ... More
Blow-up for the two-component Camassa-Holm systemJan 25 2014Following conservative solutions of the two-component Camassa-Holm system $u_t-u_{txx}+3uu_x-2u_xu_{xx}-uu_{xxx}+\rho\rho_x=0$, $\rho_t+(u\rho)_x=0$ along characteristics, we determine if wave breaking occurs in the nearby future or not, for initial data ... More
The free pseudospace is n-ample, but not (n+1)-ampleSep 29 2011Nov 01 2011We give a uniform construction of free pseudospaces of dimension n extending work by Baudisch and Pillay. This yields examples of $\omega$-stable theories which are n-ample, but not (n+1)-ample. The prime models of these theories are buildings associated ... More
Lagrangian boundary conditions for anti-self-dual instantons and the Atiyah-Floer conjectureJul 13 2006The purpose of this survey is to explain an approach to the Atiyah-Floer conjecture via a new instanton Floer homology with Lagrangian boundary conditions. This is a joint project with Dietmar Salamon. This paper also provides a rough guide to the analysis ... More
A family of SCFTs hosting all "very attractive" relatives of the (2)^4 Gepner modelDec 19 2005Jan 23 2006This work gives a manual for constructing superconformal field theories associated to a family of smooth K3 surfaces. A direct method is not known, but a combination of orbifold techniques with a non-classical duality turns out to yield such models. A ... More
KATRIN: A next generation tritium beta decay experiment with sub-eV sensitivity for the electron neutrino massSep 21 2001With the compelling evidence for massive neutrinos from recent neutrino-oscillation experiments, one of the most fundamental tasks of particle physics over the next years will be the determination of the absolute mass scale of neutrinos. The absolute ... More
A Note on Compactifications on Spin(7)-Holonomy ManifoldsNov 13 2000Mar 19 2001In this note we consider compactifications of ${\cal M}$-theory on $Spin(7)$-holonomy manifolds to three-dimensional Minkowski space. In these compactifications a warp factor is included. The conditions for unbroken N=1 supersymmetry give rise to determining ... More
Testing M(atrix)-Theory at Two LoopsSep 04 1997I discuss the relation between M-theory and M(atrix)-theory in flat space by considering the effective potential for the scattering of two groups of D0-branes in both theories. An explicit calculation of this potential up to two loop order in M(atrix)-theory ... More
Equality of pressures for diffeomorphisms preserving hyperbolic measuresMar 11 2008For a diffeomorphism which preserves a hyperbolic measure the potential $\phi^u=-\log|{\rm Jac} df|_{E^u}|$ is studied. Various types of pressure of $\phi^u$ are introduced. It is shown that these pressures satisfy a corresponding variational principle. ... More
On Superconformal Field Theories Associated to Very Attractive QuarticsJul 07 2003Dec 18 2005We study N=(4,4) superconformal field theories with left and right central charge c=6 which allow geometric interpretations on specific quartic hypersurfaces in CP^3. Namely, we recall the proof that the Gepner model (2)^4 admits a geometric interpretation ... More
Fredholm notions in scale calculus and Hamiltonian Floer theorySep 18 2012Oct 25 2016We give an equivalent definition of the Fredholm property for linear operators on scale Banach spaces and introduce a (nonlinear) scale Fredholm property with respect to a splitting of the domain. The latter implies the Fredholm property introduced by ... More
Non-hyperbolic behavior of geodesic flows of rank 1 surfacesAug 02 2018We prove that for the geodesic flow of a rank 1 Riemannian surface which is expansive but not Anosov the Hausdorff dimension of the set of vectors with only zero Lyapunov exponents is large.
Horseshoes for diffeormorphisms preserving hyperbolic measuresNov 26 2014Jul 19 2017We give extensions of Katok's horseshoe constructions, comment on related results, and provide a self-contained proof. We consider either a $C^{1+\alpha}$ diffeomorphism preserving a hyperbolic measure or a $C^1$ diffeomorphism preserving a hyperbolic ... More
Repellers for non-uniformly expanding maps with singular or critical pointsJun 16 2010Given an ergodic measure with positive entropy and only positive Lyapunov exponents, its dynamical quantifiers can be approximated by means of quantifiers of some family of uniformly expanding repellers. Here non-uniformly expanding maps are studied that ... More
Sharply 3-transitive groupsAug 06 2015We construct the first sharply $3$-transitive groups not arising from a near field, i.e. point stabilizers have no nontrivial abelian normal subgroup.
Strings, Black Holes and Conformal Field TheoryApr 25 1994The SL(2,R)/U(1) gauged Wess-Zumino-Witten model is an exact conformal field theory describing a black hole in two-dimensional space-time. The free field approach of Bershadsky and Kutasov is a suitable formulation of this CFT in order to compute physically ... More
Strongly transitive multiple treesOct 12 2011Oct 25 2011We give an amalgamation construction of free multiple trees with a strongly transitive automorphism group. The construction shows that any partial codistance function on a tuple of finite trees can be extended to yield multiple trees.
Consistency of Orbifold Conformal Field Theories on K3Oct 30 2000Jan 20 2002We explicitly determine the locations of G orbifold conformal field theories, G=Z_M, M=2,3,4,6, G=\hat D_n, n=4,5, or G the binary tetrahedral group \hat T, within the moduli space M^{K3} of N=(4,4) superconformal field theories associated to K3. This ... More
Solutions of the Camassa-Holm equation with accumulating breaking timesOct 30 2015Sep 05 2016We present two initial profiles to the Camassa-Holm equation which yield solutions with accumulating breaking times.
Banach space valued Cauchy-Riemann equations with totally real boundary conditionsJan 27 2004The main purpose of this paper is to give a general regularity result for Cauchy-Riemann equations in complex Banach spaces with totally real boundary conditions. The usual elliptic $L^p$-regularity results hold true under one crucial assumption: The ... More
Somersaults on unstable islandsNov 26 2014We give extensions of Katok's horseshoe constructions, comment on related results, and provide a self-contained proof. We consider either a $C^{1+\alpha}$ diffeomorphism preserving a hyperbolic measure or a $C^1$ diffeomorphism preserving a hyperbolic ... More
Anti-self-dual instantons with Lagrangian boundary conditions I : Elliptic theoryApr 11 2002Jan 27 2004We study a nonlocal boundary value problem for anti-self-dual instantons on 4-manifolds with a space-time splitting of the boundary. The model case is $\R \times Y$, where $Y$ is a compact oriented 3-manifold with boundary $\Sigma$. The restriction of ... More
Floer Field PhilosophyFeb 16 2016Floer field theory is a construction principle for e.g. 3-manifold invariants via decomposition in a bordism category and a functor to the symplectic category, and is conjectured to have natural 4-dimensional extensions. This survey provides an introduction ... More
Hodge-elliptic genera and how they govern K3 theoriesMay 28 2017Feb 15 2019The (complex) Hodge-elliptic genus and its conformal field theoretic counterpart were recently introduced by Kachru and Tripathy, refining the traditional complex elliptic genus. We construct a different, so-called chiral Hodge-elliptic genus, which is ... More
Global cracking elements: a novel tool for Galerkin-based approaches simulating quasi-brittle fractureAug 17 2019Following the so-called Cracking Elements Method (CEM), recently presented in \cite{Yiming:14,Yiming:16}, we propose a novel Galerkin-based numerical approach for simulating quasi-brittle fracture, named Global Cracking Elements Method (GCEM). For this ... More
Fredholm notions in scale calculus and Hamiltonian Floer theorySep 18 2012Jan 14 2013We give an equivalent definition of the Fredholm property for linear operators on scale Banach spaces and introduce a (nonlinear) scale Fredholm property with respect to a splitting of the domain. The latter implies the Fredholm property introduced by ... More
Snapshots of Conformal Field TheoryApr 11 2014In snapshots, this exposition introduces conformal field theory, with a focus on those perspectives that are relevant for interpreting superconformal field theory by Calabi-Yau geometry. It includes a detailed discussion of the elliptic genus as an invariant ... More
Scattering theory for Schrödinger operators on steplike, almost periodic infinite-gap backgroundsApr 04 2012We develop direct scattering theory for one-dimensional Schr\"odinger operators with steplike potentials, which are asymptotically close to different Bohr almost periodic infinite-gap potentials on different half-axes.
Multipartite entangled states in coupled quantum dots and cavity-QEDDec 06 2002We investigate the generation of multipartite entangled state in a system of N quantum dots embedded in a microcavity and examine the emergence of genuine multipartite entanglement by three different characterizations of entanglement. At certain times ... More
The vacuum induced Berry phase beyond rotating-wave approximationNov 01 2011Feb 26 2012With reference to the vacuum induced Berry phase (VIBP) obtained in the interaction of a spin-1/2 particle with quantized irradiation field under rotating-wave approximation (RWA), we present completely different treatment for the VIBP by a fully quantum ... More
Distributed-memory large deformation diffeomorphic 3D image registrationAug 11 2016We present a parallel distributed-memory algorithm for large deformation diffeomorphic registration of volumetric images that produces large isochoric deformations (locally volume preserving). Image registration is a key technology in medical image analysis. ... More
A sufficient condition for subellipticity of the d-bar-Neumann operatorMar 10 2005We give a sufficient condition for subelliptic estimates for the d-bar-Neumann operator on smoothly bounded, pseudoconvex domains in $\mathbb{C}^n$. This condition is a quantified version of McNeal's condition ($\tilde{P}$) for compactness of the d-bar-Neumann ... More
Supersymmetry Breaking, M-Theory and FluxesJul 06 2001Jul 16 2001We consider warped compactifications of ${\cal M}$-theory to three-dimensional Minkowski space on compact eight-manifolds. Taking all the leading quantum gravity corrections of eleven-dimensional supergravity into account we obtain the solution to the ... More
Compactifying M-Theory to Four DimensionsOct 30 2000Nov 07 2000We consider compactifications of ${\cal M}$-theory to four-dimensional Minkowski space on seven-dimensional non-compact manifolds. These compactifications include a warp factor which is non-constant due to the presence of sources coming from fivebranes ... More
Quantum Gravity Corrections for Schwarzschild Black HolesOct 07 1998We consider the Matrix theory proposal describing eleven-dimensional Schwarzschild black holes. We argue that the Newtonian potential between two black holes receives a genuine long range quantum gravity correction, which is finite and can be computed ... More
On density of ergodic measures and generic pointsApr 02 2014Aug 25 2015We provide conditions which guarantee that ergodic measures are dense in the simplex of invariant probability measures of a dynamical system given by a continuous map acting on a Polish space. Using them we study generic properties of invariant measures ... More
Dorronsoro's theorem in Heisenberg groupsJan 15 2019A theorem of Dorronsoro from the 1980s quantifies the fact that real-valued Sobolev functions on Euclidean spaces can be approximated by affine functions almost everywhere, and at all sufficiently small scales. We prove a variant of Dorronsoro's theorem ... More
Pseudofinite groups with NIP theory and definability in finite simple groupsFeb 15 2012We show that any pseudofinite group with NIP theory and with a finite upper bound on the length of chains of centralisers is soluble-by-finite. In particular, any NIP rosy pseudofinite group is soluble-by-finite. This generalises, and shortens the proof ... More
Invariant multi-graphs in step skew-productsJul 23 2018We study step skew-products over a finite-state shift (base) space whose fiber maps are $C^1$ injective maps on the unit interval. We show that certain invariant sets have a multi-graph structure and can be written graphs of one, two or more functions ... More
Orientations for pseudoholomorphic quiltsMar 26 2015Aug 09 2016We construct coherent orientations on moduli spaces of pseudoholomorphic quilts and determine the effect of various gluing operations on the orientations. We also investigate the behavior of the orientations under composition of Lagrangian correspondences. ... More
Exact triangle for fibered Dehn twistsMar 26 2015Jun 02 2016We use quilted Floer theory to generalize Seidel's long exact sequence in symplectic Floer theory to fibered Dehn twists. We then apply it to construct versions of the Floer and Khovanov-Rozansky exact triangles in Lagrangian Floer theory of moduli spaces ... More
The isometry group of the bounded Urysohn space is simpleNov 26 2012We show that the isometry group of the bounded Urysohn space is simple. This extends previous work by the authors.
The symmetries of the tetrahedral Kummer surface in the Mathieu group M_24Aug 05 2010Jul 20 2011We provide a method, based on Nikulin's lattice gluing techniques, which identifies the symplectic automorphisms of Kummer surfaces as permutation groups on 24 elements preserving the Golay code. In other words, we explicitly realise these symplectic ... More
Low functions of realsMar 09 2009Sep 26 2010We introduce a new notion of computable function on $\R^N$ and prove some basic properties. We give two applications, first a short proof of Yoshinaga's theorem that periods are \el (they are actually low). We also show that the low complex numbers form ... More
Decoding the geometry of conformal field theoriesMar 05 2008To certain geometries, string theory associates conformal field theories. We discuss techniques to perform the reverse procedure: To recover geometrical data from abstractly defined conformal field theories. This is done by introducing appropriate notions ... More
Topological pressure for one-dimensional holomorphic dynamical systemsMay 31 2007For a class of one-dimensional holomorphic maps f of the Riemann sphere we prove that for a wide class of potentials h the topological pressure is entirely determined by the values of h on the repelling periodic points of f. This is a version of a classical ... More
Asymptotic cones and ultrapowers of Lie groupsNov 07 2003Jan 21 2004Asymptotic cones of metric spaces were first invented by Gromov. They are metric spaces which capture the 'large-scale structure' of the underlying metric space. Later, van den Dries and Wilkie gave a more general construction of asymptotic cones using ... More
Limits and Degenerations of Unitary Conformal Field TheoriesAug 21 2003Jan 11 2004In the present paper, degeneration phenomena in conformal field theories are studied. For this purpose, a notion of convergent sequences of CFTs is introduced. Properties of the resulting limit structure are used to associate geometric degenerations to ... More
Affine $Λ$-buildings, ultrapowers of Lie groups and Riemannian symmetric spaces: an algebraic proof of the Margulis conjectureSep 11 2002Oct 24 2002In this paper, we give a general group-theoretic construction of affine $\RR$-buildings, and more generally, of affine $\Lambda$-buildings, associated to semisimple Lie groups over nonarchimedean real closed fields. The construction of Kleiner-Leeb using ... More
On weak Fraisse limitsNov 25 2017Using the natural action of $S_\infty$ we show that a countable hereditary class $\cC$ of finitely generated structures has the joint embedding property (JEP) and the weak amalgamation property (WAP) if and only if there is a structure $M$ whose isomorphism ... More
Symmetries and multipeakon solutions for the modified two-component Camassa-Holm systemApr 20 2017Compared with the two-component Camassa-Holm system, the modified two-component Camassa-Holm system introduces a regularized density which makes possible the existence of solutions of lower regularity, and in particular of multipeakon solutions. In this ... More
Context Models for OOV Word Translation in Low-Resource LanguagesJan 26 2018Out-of-vocabulary word translation is a major problem for the translation of low-resource languages that suffer from a lack of parallel training data. This paper evaluates the contributions of target-language context models towards the translation of ... More
Many Faces of Mimetic GravityDec 30 2015We consider the recently introduced mimetic gravity, which is a Weyl-symmetric extension of the General Relativity and which can play a role of an imperfect fluid-like Dark Matter with a small sound speed. In this paper we discuss in details how this ... More
M-Theory on Eight-ManifoldsMay 08 1996We show that in certain compactifications of ${\cal M}$-theory on eight-manifolds to three-dimensional Minkowski space-time the four-form field strength can have a non-vanishing expectation value, while an $N=2$ supersymmetry is preserved. For these compactifications ... More
Fivebrane Gravitational AnomaliesNov 18 1999Dec 03 1999Freed, Harvey, Minasian and Moore have proposed a mechanism to cancel the gravitational anomaly of the M-theory fivebrane coming from diffeomorphisms acting on the normal bundle. This procedure is based on a modification of the conventional M-theory Chern-Simons ... More
Instanton Action for Type II HypermultipletsJan 25 1999Apr 08 1999We analyze the hypermultiplet moduli space describing the universal sector of type IIA theory compactified on a Calabi-Yau threefold. The classical moduli space is described in terms of the coset $SU(2,1)/U(2)$. The flux quantization condition of the ... More
Complete Solution for M(atrix) Theory at Two LoopsJul 23 1998The complete result for the effective potential for two graviton exchange at two loops in M(atrix) theory can be expressed in terms of a generalized hypergeometric function.
Quilted Floer CohomologyMay 09 2009Aug 13 2010We generalize Lagrangian Floer cohomology to sequences of Lagrangian correspondences. For sequences related by the geometric composition of Lagrangian correspondences we establish an isomorphism of the Floer cohomologies. We give applications to calculations ... More
\emph{Addendum to} Sharply $2$-transitive groups of characteristic~$0$ [arXiv:1604.00573]Mar 07 2017In this short note we show how to modify the construction of non-split sharply $2$-transitive groups of characteristic~$0$ given by Rips and Tent [arXiv:1604.00573] to allow for arbitrary fields of characteristic 0
Simple factor dressing and the Lopez-Ros deformation of minimal surfaces in Euclidean 3-spaceSep 18 2014The aim of this paper is to give a new link between integrable systems and minimal surface theory. The dressing operation uses the associated family of flat connections of a harmonic map to construct new harmonic maps. Since a minimal surface in 3-space ... More
An alternative axiomization of $N$-pseudospacesMay 01 2017We give a new axiomatization of the N-pseudospace, studied in [2] (Tent(2014)) and [1] (Baudisch,Martin-Pizarro,Ziegler(2014)) based on the zigzags introduced in [2]. We also present a more detailed account of the characterization of forking given in ... More
Existence and Lipschitz stability for $α$-dissipative solutions of the two-component Hunter-Saxton systemOct 18 2016We establish the concept of $\alpha$-dissipative solutions for the two-component Hunter-Saxton system under the assumption that either $\alpha(x)=1$ or $0\leq \alpha(x)<1$ for all $x\in \mathbb{R}$. Furthermore, we investigate the Lipschitz stability ... More
The general peakon-antipeakon solution for the Camassa-Holm equationFeb 26 2015We compute explicitly the peakon-antipeakon solution of the Camassa-Holm equation $u_t-u_{txx}+3uu_x-2u_xu_{xx}-uu_{xxx}=0$ in the non-symmetric and $\alpha$-dissipative case. The solution experiences wave breaking in finite time, and the explicit solution ... More
Building-like geometries of finite Morley RankJun 20 2016Sep 25 2016For any $n\geq 6$ we construct almost strongly minimal geometries of type $\bullet \overset{n}{-} \bullet \overset{n}{-}\bullet$ which are $2$-ample but not $3$-ample.
Dominated Pesin theory: convex sum of hyperbolic measuresMar 19 2015Feb 22 2016In the uniformly hyperbolic setting it is well known that the measure supported on periodic orbits is dense in the convex space of all invariant measure. In this paper we consider the reverse question, in the non-uniformly hyperbolic setting: assuming ... More
Orientations for pseudoholomorphic quiltsMar 26 2015Jun 07 2017We construct orientations on moduli spaces of pseudoholomorphic quilts with seam conditions in Lagrangian correspondences equipped with relative spin structures and determine the effect of various gluing operations on the orientations. We also investigate ... More
Exact triangle for fibered Dehn twistsMar 26 2015Mar 05 2019We use quilted Floer theory to generalize Seidel's long exact sequence in symplectic Floer theory to fibered Dehn twists. We then apply it to construct versions of the Floer and Khovanov-Rozansky exact triangles in Lagrangian Floer theory of moduli spaces ... More
Kuranishi atlases with trivial isotropy - the 2013 state of affairsAug 07 2012Aug 11 2015Kuranishi structures were introduced to symplectic topology by Fukaya and Ono and recently refined by Joyce, in order to extract homological data from compactified moduli spaces of holomorphic maps in cases where geometric regularization approaches such ... More
Geometric Aspects of D-branes and T-dualityAug 16 2009Sep 13 2009We explore the differential geometry of T-duality and D-branes. Because D-branes and RR-fields are properly described via K-theory, we discuss the (differential) K-theoretic generalization of T-duality and its application to the coupling of D-branes to ... More
Exceptional sets for nonuniformly hyperbolic diffeomorphismsDec 29 2017For a surface diffeomorphism, a compact invariant locally maximal set $W$ and some subset $A\subset W$ we study the $A$-exceptional set, that is, the set of points whose orbits do not accumulate at $A$. We show that if the Hausdorff dimension of $A$ is ... More
Random iterations of homeomorphisms on the circleOct 02 2017Oct 31 2017We study random independent and identically distributed iterations of functions from an iterated function system of homeomorphisms on the circle which is minimal. We show how such systems can be analyzed in terms of iterated function systems with probabilities ... More
The Lyapunov spectrum of some parabolic systemsSep 18 2007We study the Hausdorff dimension spectrum for Lyapunov exponents for a class of interval maps which includes several non-hyperbolic situations. We also analyze the level sets of points with given lower and upper Lyapunov exponents and, in particular, ... More
A Maslov cocycle for unitary groupsJul 16 2007May 16 2009We introduce a 2-cocycle for symplectic and skew-hermitian hyperbolic groups over arbitrary fields and skew fields, with values in the Witt group of hermitian forms. This cocycle has good functorial properties: it is natural under extension of scalars ... More
The PI Property of Graded Hecke AlgebrasAug 14 2006We show that graded Hecke algebras are PI algebras if and only if they are finitely generated over their centres if and only if the deformation parameters $t_{i}$ are zero for all $i=1,\ldots,N$. This generalises a result for symplectic reflection algebras ... More
Using Pupil Diameter to Measure Cognitive LoadNov 29 2018In this paper, we will present a method for measuring cognitive load and online real-time feedback using the Tobii Pro 2 eye-tracking glasses. The system is envisaged to be capable of estimating high cognitive load states and situations, and adjust human-machine ... More
Exceptional sets for nonuniformly expanding mapsJun 01 2015Feb 15 2016Given a rational map of the Riemann sphere and a subset $A$ of its Julia set, we study the $A$-exceptional set, that is, the set of points whose orbit does not accumulate at $A$. We prove that if the topological entropy of $A$ is less than the topological ... More
Sharply $2$-transitive groupsAug 24 2014We give an explicit construction of sharply $2$-transitive groups with fixed point free involutions and without nontrivial abelian normal subgroup.
Symmetry-surfing the moduli space of Kummer K3sMar 12 2013Jan 23 2015A maximal subgroup of the Mathieu group M24 arises as the combined holomorphic symplectic automorphism group of all Kummer surfaces whose Kaehler class is induced from the underlying complex torus. As a subgroup of M24, this group is the stabilizer group ... More
Robustness of a bisimulation-type faster-than preorderNov 15 2009TACS is an extension of CCS where upper time bounds for delays can be specified. Luettgen and Vogler defined three variants of bismulation-type faster-than relations and showed that they all three lead to the same preorder, demonstrating the robustness ... More
Heterotic Strings with TorsionSep 09 2002Dec 04 2002In this paper we describe the heterotic dual of the type IIB theory compactified to four dimensions on a toroidal orientifold in the presence of fluxes. The type IIB background is most easily described in terms of an M-theory compactification on a four-fold. ... More
Cluster deprojection with joint lensing, X-ray, and Sunyaev-Zeldovich dataSep 09 1999We propose a new cluster deprojection algorithm for recovering cluster structure along the line of sight (los) based on the Richardson-Lucy (RL) algorithm, which recovers a nonnegative theoretical distribution from a given projection. To optimize our ... More