Results 51 to 60 of about 1,101 (187)

Existence, Uniqueness, and Mittag–Leffler–Ulam Stability Results for Cauchy Problem Involving ψ-Caputo Derivative in Banach and Fréchet Spaces

International Journal of Differential Equations, 2020
Our aim in this paper is to investigate the existence, uniqueness, and Mittag–Leffler–Ulam stability results for a Cauchy problem involving ψ-Caputo fractional derivative with positive constant coefficient in Banach and Fréchet Spaces.
Choukri Derbazi, Zidane Baitiche, Mouffak Benchohra, G. N’Guérékata   +3 more
doaj   +1 more source

Validation of machine learning based scenario generators

Journal of Risk and Insurance, EarlyView.
Abstract Machine learning (ML) methods are becoming increasingly important for designing economic scenario generators for internal models. Validating data‐driven models requires different methods than validating classical, theory‐based models. We discuss two novel aspects of such validation: first, checking the multivariate distribution of risk factors,
Gero Junike, Solveig Flaig, Ralf Werner
wiley   +1 more source

A Conditional Tail Expectation Type Risk Measure for Time Series

Journal of Time Series Analysis, EarlyView.
ABSTRACT We consider the estimation of the conditional expectation 𝔼(Xh|X0>UX(1/p)), provided 𝔼|X0|<∞, at extreme levels, where (Xt)t∈ℤ$$ {\left({X}_t\right)}_{t\in \mathbb{Z}} $$ is a strictly stationary time series, UX$$ {U}_X $$ its tail quantile function, h$$ h $$ is a positive integer and p∈(0,1)$$ p\in \left(0,1\right) $$ is such that p→0$$ p\to ...
Yuri Goegebeur, Armelle Guillou, Jing Qin   +2 more
wiley   +1 more source

Dependence of eigenvalue of Sturm-Liouville problem with singular potential and eigenparameter-dependent boundary conditions(边界条件含有谱参数的奇异Sturm-Liouville算子特征值的依赖性)

Zhejiang Daxue xuebao. Lixue ban
In this paper, we study the dependence of eigenvalue of Sturm-Liouville operator with distributed potential function and prove the continuous dependence of eigenvalue branch by establishing boundary condition space and constructing embedded mapping ...
仲林路(ZHONG Linlu), 杜高峰(DU Gaofeng)   +1 more
doaj   +1 more source

Density‐Valued ARMA Models by Spline Mixtures

Journal of Time Series Analysis, EarlyView.
ABSTRACT This paper proposes a novel framework for modeling time series of probability density functions by extending autoregressive moving average (ARMA) models to density‐valued data. The method is based on a transformation approach, wherein each density function on a compact domain [0,1]d$$ {\left[0,1\right]}^d $$ is approximated by a B‐spline ...
Yasumasa Matsuda, Rei Iwafuchi
wiley   +1 more source

A Note on Local Polynomial Regression for Time Series in Banach Spaces

Journal of Time Series Analysis, EarlyView.
ABSTRACT This work extends local polynomial regression to Banach space‐valued time series for estimating smoothly varying means and their derivatives in non‐stationary data. The asymptotic properties of both the standard and bias‐reduced Jackknife estimators are analyzed under mild moment conditions, establishing their convergence rates.
Florian Heinrichs
wiley   +1 more source

Sequential Outlier Detection in Nonstationary Time Series

Journal of Time Series Analysis, EarlyView.
ABSTRACT A novel method for sequential outlier detection in nonstationary time series is proposed. The method tests the null hypothesis of “no outlier” at each time point, addressing the multiple testing problem by bounding the error probability of successive tests, using extreme‐value theory. The asymptotic properties of the test statistic are studied
Florian Heinrichs, Patrick Bastian, Holger Dette   +2 more
wiley   +1 more source

Testing Distributional Granger Causality With Entropic Optimal Transport

Journal of Time Series Analysis, EarlyView.
ABSTRACT We develop a novel nonparametric test for Granger causality in distribution based on entropic optimal transport. Unlike classical mean‐based approaches, the proposed method directly compares the full conditional distributions of a response variable with and without the history of a candidate predictor.
Tao Wang
wiley   +1 more source

Robust Bernoulli Mixture Models for Credit Portfolio Risk

Mathematical Finance, EarlyView.
ABSTRACT This paper presents comparison results and establishes risk bounds for credit portfolios within classes of Bernoulli mixture models, assuming conditionally independent defaults that are stochastically increasing in a common risk factor. We provide simple and interpretable conditions on conditional default probabilities that imply a comparison ...
Jonathan Ansari, Eva Lütkebohmert
wiley   +1 more source

Omnibus goodness‐of‐fit tests for univariate continuous distributions based on trigonometric moments

Statistica Neerlandica, Volume 80, Issue 2, May 2026.
ABSTRACT We propose a new omnibus goodness‐of‐fit test based on trigonometric moments of probability‐integral‐transformed data. The test builds on the framework of the LK test introduced by Langholz and Kronmal [J. Amer. Statist. Assoc. 86 (1991), 1077–1084], but fully exploits the covariance structure of the associated trigonometric statistics.
Alain Desgagné, Frédéric Ouimet
wiley   +1 more source