Open Access Repositories: Recent submissions

Now showing items 61-80 of 4204

  • Statistical and computational trade-offs in estimation of sparse principal components 

    Wang, Tengyao; Berthet, Quentin; Samworth, Richard John (Institute of Mathematical StatisticsAnnals of Statistics, 2016)
    In recent years, Sparse Principal Component Analysis has emerged as an extremely popular dimension reduction technique for highdimensional data. The theoretical challenge, in the simplest case, is to estimate the leading ...

  • Generalised additive and index models with shape constraints 

    Chen, Yining; Samworth, Richard John (WileyJournal of the Royal Statistical Society: Series B (Statistical Methodology), 2015-10-26)
    We study generalized additive models, with shape restrictions (e.g. monotonicity, convexity and concavity) imposed on each component of the additive prediction function. We show that this framework facilitates a non-parametric ...

  • Transversals as Generating Sets in Finitely Generated Groups 

    Button, Jack; Chiodo, Maurice Charles; Laris, Mariano Zeron-Medina (Cambridge University PressBulletin of the Australian Mathematical Society, 2015-08-19)
    We explore transversals of finite index subgroups of finitely generated groups. We show that when H is a subgroup of a rank n group G and H has index at least n in G then we can construct a left transversal for H which ...

  • Near-optimal estimation of jump activity in semimartingales 

    Bull, Adam David (Institute of Mathematical StatisticsThe Annals of Statistics, 2015-07-15)
    In quantitative finance, we often model asset prices as semimartingales, with drift, diffusion and jump components. The jump activity index measures the strength of the jumps at high frequencies, and is of interest both ...


  • Towards Automatic Model Comparison: An Adaptive Sequential Monte Carlo Approach 

    Zhou, Yan; Johansen, Adam M; Aston, John Alexander (Taylor & FrancisJournal of Computational and Graphical Statistics, 2015-08-17)
    Model comparison for the purposes of selection, averaging and validation is a problem found throughout statistics. Within the Bayesian paradigm, these problems all require the calculation of the posterior probabilities of ...

  • A Functional Approach to Deconvolve Dynamic Neuroimaging Data 

    Jiang, CR; Aston, John Alexander; Wang, JL (Taylor & FrancisJournal of the American Statistical Association, 2015-11-20)
    Positron Emission Tomography (PET) is an imaging technique which can be used to investigate chemical changes in human biological processes such as cancer development or neurochemical reactions. Most dynamic PET scans are ...

  • On the motive of some hyperKaehler varieties 

    Vial, Charles Louis (De GruyterJournal für die reine und angewandte Mathematik, 2015-06-05)
    We show that the motive of the Hilbert scheme of length-n subschemes on a K3 surface or on an abelian surface admits a decomposition similar to the decomposition of the motive of an abelian variety obtained by Shermenev, ...

  • F-Saturation Games 

    Lee, Jonathan D.; Riet, Ago-Erik (ElsevierDiscrete Mathematics, 2015-06-23)
    We study F-saturation games, first introduced by Füredi, Reimer and Seress [4] in 1991, and named as such by West [5]. The main question is to determine the length of the game whilst avoiding various classes of graph, ...

  • Stability of charged rotating black holes for linear scalar perturbations 

    Civin, Damon (University of CambridgeDepartment of Pure Mathematics and Mathematical StatisticsCambridge Centre for Analysis, 2015-03-03)
    In this thesis, the stability of the family of subextremal Kerr-Newman space- times is studied in the case of linear scalar perturbations. That is, nondegenerate energy bounds (NEB) and integrated local energy decay ...

  • Characterisation of gradient flows on finite state Markov chains 

    Dietert, Helge (Institute of Mathematical StatisticsElectronic Communications in Probability, 2015-03-29)
    In his 2011 work, Maas has shown that the law of any time-reversible continuoustime Markov chain with finite state space evolves like a gradient flow of the relative entropy with respect to its stationary distribution. ...

  • Groups and embeddings in SL(2, C) 

    Button, Jack (Taylor & FrancisCommunications in Algebra, 2015-10-19)
    We give results on when a finitely generated torsion free group does or does not embed in SL(2, C). For instance if we glue two copies of the figure 8 knot along its torus boundary then the fundamental group of the resulting ...

  • Automorphy of some residually dihedral Galois representations 

    Thorne, Jack Arfon (Springer, 2015-05-08)
    We establish the automorphy of some families of 2-dimensional representations of the absolute Galois group of a totally real field, which do not satisfy the so-called ‘Taylor–Wiles hypothesis’. We apply this to the problem ...

  • Invariant distributions, Beurling transforms and tensor tomography in higher dimensions 

    Paternain, Gabriel Pedro; Salo, Mikko; Uhlmann, Gunther (SpringerMathematische Annalen, 2015-02-01)
    In the recent articles [PSU13, PSU14c], a number of tensor tomography results were proved on two-dimensional manifolds. The purpose of this paper is to extend some of these methods to manifolds of any dimension. A central ...

  • Unifying Amplitude and Phase Analysis Unifying Amplitude and Phase Analysis. A Compositional Data Approach to Functional Multivariate Mixed-Effects Modeling of Mandarin Chinese 

    Hadjipantelis, PZ; Aston, John Alexander; Müller, HG; Evans, JP (Taylor & FrancisJournal of the American Statistical Association, 2015-07-06)
    Mandarin Chinese is characterized by being a tonal language; the pitch (or F0) of its utterances carries considerable linguistic information. However, speech samples from different individuals are subject to changes in ...

  • The Triviality problem for profinite completions 

    Bridson, Martin R; Wilton, Henry John (SpringerInventiones Mathematicae, 2015-02-24)
    We prove that there is no algorithm that can determine whether or not a finitely presented group has a non-trivial finite quotient; indeed, this property remains undecidable among the fundamental groups of compact, ...

  • Equidistribution of Frobenius eigenvalues 

    Thorne, Jack Arfon (Oxford JournalsInternational Mathematics Research Notices, 2015-02-09)
    We study the problem of variation of Frobenius eigenvalues on the cohomology of families of local systems of algebraic curves over finite fields.

  • Exact Lagrangian immersions with a single double point 

    Ekholm, Tobias; Smith, Ivan (American Mathematical Society, 2015-01-09)
    We show that if a closed orientable 2k-manifold K, k > 2, with Euler characteristic χ(K) ≠ -2 admits an exact Lagrangian immersion into C2k with one transverse double point and no other self intersections, then K is ...

  • Hidden states, hidden structures: Bayesian learning in time series models 

    Murphy, James Kevin (University of CambridgeDepartment of Engineering, 2014-06-10)
    This thesis presents methods for the inference of system state and the learning of model structure for a number of hidden-state time series models, within a Bayesian probabilistic framework. Motivating examples are taken ...

  • Trading to stops 

    Imkeller, Nora; Rogers, Leonard Christopher (Society for Industrial and Applied MathematicsSiam Journal on Financial Mathematics, 2014-12-16)
    The use of trading stops is a common practice in financial markets for a variety of reasons: it reduces the frequency of trading and thereby transaction costs; it provides a simple way to control losses on a given trade, ...