Search Results for author: Cristian R. Rojas

Found 29 papers, 0 papers with code

Kernel-based learning with guarantees for multi-agent applications

no code implementations15 Apr 2024 Krzysztof Kowalczyk, Paweł Wachel, Cristian R. Rojas

This paper addresses a kernel-based learning problem for a network of agents locally observing a latent multidimensional, nonlinear phenomenon in a noisy environment.

Consistency analysis of refined instrumental variable methods for continuous-time system identification in closed-loop

no code implementations13 Apr 2024 Rodrigo A. González, Siqi Pan, Cristian R. Rojas, James S. Welsh

In this paper, we address the consistency of the simplified refined instrumental variable method for continuous-time systems (SRIVC) and its closed-loop variant CLSRIVC when they are applied on data that is generated from a feedback loop.

Statistical Analysis of Block Coordinate Descent Algorithms for Linear Continuous-time System Identification

no code implementations13 Apr 2024 Rodrigo A. González, Koen Classens, Cristian R. Rojas, James S. Welsh, Tom Oomen

Block coordinate descent is an optimization technique that is used for estimating multi-input single-output (MISO) continuous-time models, as well as single-input single output (SISO) models in additive form.

Coherence-based Input Design for Sparse System Identification

no code implementations8 Feb 2024 Javad Parsa, Cristian R. Rojas, Håkan Hjalmarsson

The maximum absolute correlation between regressors, which is called mutual coherence, plays an essential role in sparse estimation.

Identification of Additive Continuous-time Systems in Open and Closed-loop

no code implementations2 Jan 2024 Rodrigo A. González, Koen Classens, Cristian R. Rojas, James S. Welsh, Tom Oomen

When identifying electrical, mechanical, or biological systems, parametric continuous-time identification methods can lead to interpretable and parsimonious models when the model structure aligns with the physical properties of the system.

Additive models

Unraveling the Control Engineer's Craft with Neural Networks

no code implementations20 Nov 2023 Braghadeesh Lakshminarayanan, Federico Dettù, Cristian R. Rojas, Simone Formentin

In this paper, we present a sim2real, direct data-driven controller tuning approach, where the digital twin is used to generate input-output data and suitable controllers for several perturbations in its parameters.

Meta-Learning

DRCFS: Doubly Robust Causal Feature Selection

no code implementations12 Jun 2023 Francesco Quinzan, Ashkan Soleymani, Patrick Jaillet, Cristian R. Rojas, Stefan Bauer

Knowing the features of a complex system that are highly relevant to a particular target variable is of fundamental interest in many areas of science.

feature selection

On the Relation between Discrete and Continuous-time Refined Instrumental Variable Methods

no code implementations31 May 2023 Rodrigo A. González, Cristian R. Rojas, Siqi Pan, James S. Welsh

The Refined Instrumental Variable method for discrete-time systems (RIV) and its variant for continuous-time systems (RIVC) are popular methods for the identification of linear systems in open-loop.

Relation

Decentralized diffusion-based learning under non-parametric limited prior knowledge

no code implementations5 May 2023 Paweł Wachel, Krzysztof Kowalczyk, Cristian R. Rojas

We study the problem of diffusion-based network learning of a nonlinear phenomenon, $m$, from local agents' measurements collected in a noisy environment.

An EM Algorithm for Lebesgue-sampled State-space Continuous-time System Identification

no code implementations6 Apr 2023 Rodrigo A. González, Angel L. Cedeño, María Coronel, Juan C. Agüero, Cristian R. Rojas

This paper concerns the identification of continuous-time systems in state-space form that are subject to Lebesgue sampling.

Parsimonious Identification of Continuous-Time Systems: A Block-Coordinate Descent Approach

no code implementations6 Apr 2023 Rodrigo A. González, Cristian R. Rojas, Siqi Pan, James S. Welsh

The identification of electrical, mechanical, and biological systems using data can benefit greatly from prior knowledge extracted from physical modeling.

Optimal Transport for Correctional Learning

no code implementations4 Apr 2023 Rebecka Winqvist, Inês Lourenco, Francesco Quinzan, Cristian R. Rojas, Bo Wahlberg

In this framework, an expert agent, referred to as the teacher, modifies the data used by a learning agent, known as the student, to improve its estimation process.

A Unified Approach to Differentially Private Bayes Point Estimation

no code implementations18 Nov 2022 Braghadeesh Lakshminarayanan, Cristian R. Rojas

Standard algorithms for differentially private estimation are based on adding an appropriate amount of noise to the output of a traditional point estimation method.

On state-space representations of general discrete-time dynamical systems

no code implementations6 May 2022 Cristian R. Rojas, Pawel Wachel

In this paper we establish that every (deterministic) non-autonomous, discrete-time, causal, time invariant system has a state-space representation, and discuss its minimality.

A Statistical Decision-Theoretical Perspective on the Two-Stage Approach to Parameter Estimation

no code implementations31 Mar 2022 Braghadeesh Lakshminarayanan, Cristian R. Rojas

One of the most important problems in system identification and statistics is how to estimate the unknown parameters of a given model.

Model Optimization

A Teacher-Student Markov Decision Process-based Framework for Online Correctional Learning

no code implementations15 Nov 2021 Inês Lourenço, Rebecka Winqvist, Cristian R. Rojas, Bo Wahlberg

A classical learning setting typically concerns an agent/student who collects data, or observations, from a system in order to estimate a certain property of interest.

Asymptotically Optimal Bandits under Weighted Information

no code implementations28 May 2021 Matias I. Müller, Cristian R. Rojas

We study the problem of regret minimization in a multi-armed bandit setup where the agent is allowed to play multiple arms at each round by spreading the resources usually allocated to only one arm.

Thompson Sampling

Consistency Analysis of the Closed-loop SRIVC Estimator

no code implementations23 Mar 2021 Siqi Pan, James S. Welsh, Rodrigo A. Gonzalez, Cristian R. Rojas

The Consistency of the Closed-Loop Simplified Refined Instrumental Variable method for Continuous-time system (CLSRIVC) is analysed based on sampled data.

Non-causal regularized least-squares for continuous-time system identification with band-limited input excitations

no code implementations19 Mar 2021 Rodrigo A. González, Cristian R. Rojas, Håkan Hjalmarsson

In continuous-time system identification, the intersample behavior of the input signal is known to play a crucial role in the performance of estimation methods.

Cooperative System Identification via Correctional Learning

no code implementations9 Dec 2020 Inês Lourenço, Robert Mattila, Cristian R. Rojas, Bo Wahlberg

We consider a cooperative system identification scenario in which an expert agent (teacher) knows a correct, or at least a good, model of the system and aims to assist a learner-agent (student), but cannot directly transfer its knowledge to the student.

A Finite-Sample Deviation Bound for Stable Autoregressive Processes

no code implementations L4DC 2020 Rodrigo A. González, Cristian R. Rojas

In this paper, we study non-asymptotic deviation bounds of the least squares estimator in Gaussian AR($n$) processes.

Bayesian Model Selection for Change Point Detection and Clustering

no code implementations ICML 2018 Othmane Mazhar, Cristian R. Rojas, Carlo Fischione, Mohammad R. Hesamzadeh

We address the new problem of estimating a piece-wise constant signal with the purpose of detecting its change points and the levels of clusters.

Change Point Detection Clustering +1

Estimator Selection: End-Performance Metric Aspects

no code implementations26 Jul 2015 Dimitrios Katselis, Cristian R. Rojas, Carolyn L. Beck

The separation of the system estimator from the experiment design is done within this new framework by choosing and fixing the estimation method to either a maximum likelihood (ML) approach or a Bayesian estimator such as the minimum mean square error (MMSE).

Bayesian Learning for Low-Rank matrix reconstruction

no code implementations23 Jan 2015 Martin Sundin, Cristian R. Rojas, Magnus Jansson, Saikat Chatterjee

We develop latent variable models for Bayesian learning based low-rank matrix completion and reconstruction from linear measurements.

Low-Rank Matrix Completion

How to monitor and mitigate stair-casing in l1 trend filtering

no code implementations1 Dec 2014 Cristian R. Rojas, Bo Wahlberg

It is known that TV denoising suffers from the so-called stair-case effect, which leads to detecting false change points.

Denoising Time Series +1

Approximate Regularization Path for Nuclear Norm Based H2 Model Reduction

no code implementations22 Jul 2014 Niclas Blomberg, Cristian R. Rojas, Bo Wahlberg

This paper concerns model reduction of dynamical systems using the nuclear norm of the Hankel matrix to make a trade-off between model fit and model complexity.

On change point detection using the fused lasso method

no code implementations21 Jan 2014 Cristian R. Rojas, Bo Wahlberg

In this paper we analyze the asymptotic properties of l1 penalized maximum likelihood estimation of signals with piece-wise constant mean values and/or variances.

Change Point Detection Denoising +2

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