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Vector autoregressive (VAR) models are popularly adopted for modelling high-dimensional time series, and their piecewise extensions allow for structural changes in the data. In VAR modelling, the number of parameters grow quadratically with…

Methodology · Statistics 2023-01-23 Haeran Cho , Hyeyoung Maeng , Idris A. Eckley , Paul Fearnhead

We develop a procedure for forecasting the volatility of a time series immediately following a news shock. Adapting the similarity-based framework of Lin and Eck (2020), we exploit series that have experienced similar shocks. We aggregate…

Methodology · Statistics 2024-08-08 David P. Lundquist , Daniel J. Eck

Using high frequency data, we have studied empirically the change of volatility, also called volatility derivative, for various time horizons. In particular, the correlation between the volatility derivative and the volatility realized in…

Statistical Mechanics · Physics 2009-11-07 Gilles Zumbach , Paul Lynch

The Dynamical Gaussian Process Latent Variable Models provide an elegant non-parametric framework for learning the low dimensional representations of the high-dimensional time-series. Real world observational studies, however, are often…

Machine Learning · Computer Science 2019-09-26 Thanh Le , Vasant Honavar

We propose a flexible Bayesian approach for sparse Gaussian graphical modeling of multivariate time series. We account for temporal correlation in the data by assuming that observations are characterized by an underlying and unobserved…

Methodology · Statistics 2025-08-21 Beniamino Hadj-Amar , Aaron M. Bornstein , Michele Guindani , Marina Vannucci

Price range contains important information about the asset volatility, and has long been considered an important indicator for it. In this paper, we propose to jointly model the [low, high] price range as a random interval and introduce an…

Methodology · Statistics 2015-02-18 Yan Sun , Jennifer Loveland , Isaac Blackhurst

One of the most important features of financial time series data is volatility. There are often structural changes in volatility over time, and an accurate estimation of the volatility of financial time series requires careful…

Methodology · Statistics 2022-10-24 Huaiyu Hu , Ashis Gangopadhyay

Estimating the covariance structure of multivariate time series is a fundamental problem with a wide-range of real-world applications -- from financial modeling to fMRI analysis. Despite significant recent advances, current state-of-the-art…

Machine Learning · Computer Science 2021-02-12 Hrayr Harutyunyan , Daniel Moyer , Hrant Khachatrian , Greg Ver Steeg , Aram Galstyan

Large language models (LLMs) have revolutionized natural language processing, yet their practical utility is often limited by persistent issues of hallucinations and outdated parametric knowledge. Although post-training model editing offers…

Computation and Language · Computer Science 2026-02-03 Yash Kumar Atri , Ahmed Alaa , Thomas Hartvigsen

The frozen Gaussian approximation (FGA) is an effective tool for modeling high frequency wave propagation. In previous works, the convergence of the FGA has established for strict hyperbolic systems. In this work, we derive the frozen…

Mathematical Physics · Physics 2019-11-04 James Hateley , Xu Yang

Stochastic processes are a flexible and widely used family of models for statistical modeling. While stochastic processes offer attractive properties such as inclusion of uncertainty properties, their inference is typically intractable,…

Methodology · Statistics 2026-02-10 Teemu Härkönen , Simo Särkkä

Adaptive Retrieval-Augmented Generation (RAG) promises accuracy and efficiency by dynamically triggering retrieval only when needed and is widely used in practice. However, real-world queries vary in surface form even with the same intent,…

Computation and Language · Computer Science 2026-04-14 Yunah Jang , Megha Sundriyal , Kyomin Jung , Meeyoung Cha

Retrieval-augmented generation (RAG) enables large language models (LLMs) to access external knowledge, helping mitigate hallucinations and enhance domain-specific expertise. Graph-based RAG enhances structural reasoning by introducing…

Computation and Language · Computer Science 2025-11-26 Linxiao Cao , Ruitao Wang , Jindong Li , Zhipeng Zhou , Menglin Yang

In this paper we study the asymptotic behavior of the Gaussian quasi maximum likelihood estimator of a stationary GARCH process with heavy-tailed innovations. This means that the innovations are regularly varying with index…

Statistics Theory · Mathematics 2007-06-13 Thomas Mikosch , Daniel Straumann

In this paper we propose an identification method for latent-variable graphical models associated to autoregressive (AR) Gaussian stationary processes. The identification procedure exploits the approximation of AR processes through…

Optimization and Control · Mathematics 2018-09-06 Daniele Alpago , Mattia Zorzi , Augusto Ferrante

The bivariate copulas that describe the dependencies and partial dependencies of lagged variables in strictly stationary, first-order GARCH-type processes are investigated. It is shown that the copulas of symmetric GARCH processes are…

Methodology · Statistics 2025-10-10 Alexandra Dias , Jialing Han , Alexander J. McNeil

Despite recent remarkable achievements in quadruped control, it remains challenging to ensure robust and compliant locomotion in the presence of unforeseen external disturbances. Existing methods prioritize locomotion robustness over…

Robotics · Computer Science 2025-07-04 Xiang Zhou , Xinyu Zhang , Qingrui Zhang

We consider the problem of modeling high-speed flows using machine learning methods. While most prior studies focus on low-speed fluid flows in which uniform time-stepping is practical, flows approaching and exceeding the speed of sound…

Graph-based Retrieval-Augmented Generation (Graph-RAG) enhances large language models (LLMs) by structuring retrieval over an external corpus. However, existing approaches typically assume a static corpus, requiring expensive full-graph…

Information Retrieval · Computer Science 2025-07-08 Fangyuan Zhang , Zhengjun Huang , Yingli Zhou , Qintian Guo , Zhixun Li , Wensheng Luo , Di Jiang , Yixiang Fang , Xiaofang Zhou

Retrieval-Augmented Generation (RAG) has emerged as a powerful approach for enhancing large language models' question-answering capabilities through the integration of external knowledge. However, when adapting RAG systems to specialized…

Computation and Language · Computer Science 2026-01-19 Xin Sun , Zhongqi Chen , Qiang Liu , Shu Wu , Bowen Song , Weiqiang Wang , Zilei Wang , Liang Wang