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This work is concerned with the derivation of a robust a posteriori error estimator for a discontinuous Galerkin method discretisation of linear non-stationary convection-diffusion initial/boundary value problems and with the implementation…

Numerical Analysis · Mathematics 2012-11-16 Andrea Cangiani , Emmanuil H. Georgoulis , Stephen Metcalfe

A popular technique for selecting and tuning machine learning estimators is cross-validation. Cross-validation evaluates overall model fit, usually in terms of predictive accuracy. In causal inference, the optimal choice of estimator…

Methodology · Statistics 2021-07-07 Dominik Rothenhäusler

In this paper, we develop a new residual-based pointwise a posteriori error estimator of the quadratic finite element method for the Signorini problem. The supremum norm a posteriori error estimates enable us to locate the singularities…

Numerical Analysis · Mathematics 2024-01-05 Rohit Khandelwal , Kamana Porwal , Tanvi Wadhawan

In this paper, we describe a framework to compute expected convergence rates for residuals based on the Calder\'on identities for general second order differential operators for which fundamental solutions are known. The idea is that these…

Numerical Analysis · Mathematics 2025-04-01 Ralf Hiptmair , Carolina Urzúa-Torres , Anouk Wisse

Non-stationary extremal dependence, whereby the relationship between the extremes of multiple variables evolves over time, is commonly observed in many environmental and financial data sets. However, most multivariate extreme value models…

Methodology · Statistics 2025-09-29 C. J. R. Murphy-Barltrop , J. L. Wadsworth , M. de Carvalho , B. D. Youngman

We consider a recursive algorithm to construct an aggregated estimator from a finite number of base decision rules in the classification problem. The estimator approximately minimizes a convex risk functional under the l1-constraint. It is…

Statistics Theory · Mathematics 2007-06-13 Anatoli Juditsky , Alexander Nazin , Alexandre Tsybakov , Nicolas Vayatis

This manuscript proposes a probabilistic framework for algorithms that iteratively solve unconstrained linear problems $Bx = b$ with positive definite $B$ for $x$. The goal is to replace the point estimates returned by existing methods with…

Optimization and Control · Mathematics 2014-10-16 Philipp Hennig

We consider variants of a recently-developed Newton-CG algorithm for nonconvex problems \citep{royer2018newton} in which inexact estimates of the gradient and the Hessian information are used for various steps. Under certain conditions on…

Optimization and Control · Mathematics 2022-04-12 Zhewei Yao , Peng Xu , Fred Roosta , Stephen J. Wright , Michael W. Mahoney

In this article, we focus on the error that is committed when computing the matrix logarithm using the Gauss--Legendre quadrature rules. These formulas can be interpreted as Pad\'e approximants of a suitable Gauss hypergeometric function.…

Numerical Analysis · Mathematics 2023-10-19 Lidia Aceto , Fabio Durastante

In this paper, we develop a restricted eigenvalue condition for unit-root non-stationary data and derive its validity under the assumption of independent Gaussian innovations that may be contemporaneously correlated. The method of proof…

Econometrics · Economics 2022-08-30 Etienne Wijler

This paper studies the problem of recursively estimating the weighted adjacency matrix of a network out of a temporal sequence of binary-valued observations. The observation sequence is generated from nonlinear networked dynamics in which…

Systems and Control · Electrical Eng. & Systems 2019-12-06 Yu Xing , Xingkang He , Haitao Fang , Karl Henrik Johansson

Gradient algorithms are classical in adaptive control and parameter estimation. For instantaneous quadratic cost functions they lead to a linear time-varying dynamic system that converges exponentially under persistence of excitation…

Optimization and Control · Mathematics 2020-10-06 Juan G. Rueda-Escobedo , Jaime A. Moreno

The classical multivariate extreme-value theory concerns the modeling of extremes in a multivariate random sample, suggesting the use of max-stable distributions. In this work, the classical theory is extended to the case where aggregated…

Methodology · Statistics 2020-03-12 Enkelejd Hashorva , Simone A. Padoan , Stefano Rizzelli

This paper investigates extreme value theory for processes obtained by applying transformations to stationary Gaussian processes, also called subordinated Gaussian processes. The main contributions are as follows. First, we refine the…

Probability · Mathematics 2026-05-29 Shuyang Bai , Marie-Christine Duker

We re-consider Leadbetter's extremal index for stationary sequences. It has interpretation as reciprocal of the expected size of an extremal cluster above high thresholds. We focus on heavy-tailed time series, in particular on regularly…

Probability · Mathematics 2021-06-10 Gloria Buriticá , Meyer Nicolas , Thomas Mikosch , Olivier Wintenberger

We study and derive algorithms for nonlinear eigenvalue problems, where the system matrix depends on the eigenvector, or several eigenvectors (or their corresponding invariant subspace). The algorithms are derived from an implicit…

Numerical Analysis · Mathematics 2020-03-02 Elias Jarlebring , Parikshit Upadhyaya

The problem of estimating a random vector x from noisy linear measurements y = A x + w with unknown parameters on the distributions of x and w, which must also be learned, arises in a wide range of statistical learning and linear inverse…

Information Theory · Computer Science 2017-06-20 Alyson K. Fletcher , Mojtaba Sahraee-Ardakan , Philip Schniter , Sundeep Rangan

In this paper, we introduce and study a new extragradient iterative process for finding a common element of the set of fixed points of an infinite family of nonexpansive mappings and the set of solutions of a variational inequality for an…

Functional Analysis · Mathematics 2014-05-22 Ibrahim Karahan , Murat Ozdemir

The multivariate extremal index function relates the asymptotic distribution of the vector of pointwise maxima of a multivariate stationary sequence to that of the independent sequence from the same stationary distribution. It also measures…

Applications · Statistics 2008-11-14 Christian Y. Robert

This work presents a numerical study of functional type a posteriori error estimates for IgA approximation schemes in the context of elliptic boundary-value problems. Along with the detailed discussion of the most crucial properties of such…

Numerical Analysis · Computer Science 2018-05-28 Svetlana Matculevich