Search Results for author: Theodoros Damoulas

Found 40 papers, 19 papers with code

Non-separable Non-stationary random fields

no code implementations ICML 2020 Kangrui Wang, Oliver Hamelijnck, Theodoros Damoulas, Mark Steel

We describe a framework for constructing non-separable non-stationary random fields that is based on an infinite mixture of convolved stochastic processes.

Generating Origin-Destination Matrices in Neural Spatial Interaction Models

1 code implementation9 Oct 2024 Ioannis Zachos, Mark Girolami, Theodoros Damoulas

Agent-based models (ABMs) are proliferating as decision-making tools across policy areas in transportation, economics, and epidemiology.

Agent-based model inverse problem Decision Making

Physics-Informed Variational State-Space Gaussian Processes

no code implementations20 Sep 2024 Oliver Hamelijnck, Arno Solin, Theodoros Damoulas

Differential equations are important mechanistic models that are integral to many scientific and engineering applications.

Gaussian Processes

Interventionally Consistent Surrogates for Agent-based Simulators

no code implementations18 Dec 2023 Joel Dyer, Nicholas Bishop, Yorgos Felekis, Fabio Massimo Zennaro, Anisoara Calinescu, Theodoros Damoulas, Michael Wooldridge

Agent-based simulators provide granular representations of complex intelligent systems by directly modelling the interactions of the system's constituent agents.

Causal Optimal Transport of Abstractions

1 code implementation13 Dec 2023 Yorgos Felekis, Fabio Massimo Zennaro, Nicola Branchini, Theodoros Damoulas

Causal abstraction (CA) theory establishes formal criteria for relating multiple structural causal models (SCMs) at different levels of granularity by defining maps between them.

Data Augmentation

Robust Bayesian Inference for Berkson and Classical Measurement Error Models

no code implementations2 Jun 2023 Charita Dellaporta, Theodoros Damoulas

This approach gives rise to a general framework that is suitable for both Classical and Berkson error models via the appropriate specification of the prior centering measure of a Dirichlet Process (DP).

Bayesian Inference

Quantifying Consistency and Information Loss for Causal Abstraction Learning

1 code implementation7 May 2023 Fabio Massimo Zennaro, Paolo Turrini, Theodoros Damoulas

However, switching between different levels of abstraction requires evaluating a trade-off between the consistency and the information loss among different models.

Jointly Learning Consistent Causal Abstractions Over Multiple Interventional Distributions

1 code implementation14 Jan 2023 Fabio Massimo Zennaro, Máté Drávucz, Geanina Apachitei, W. Dhammika Widanage, Theodoros Damoulas

An abstraction can be used to relate two structural causal models representing the same system at different levels of resolution.

Causal Entropy Optimization

no code implementations23 Aug 2022 Nicola Branchini, Virginia Aglietti, Neil Dhir, Theodoros Damoulas

We study the problem of globally optimizing the causal effect on a target variable of an unknown causal graph in which interventions can be performed.

Bayesian Optimization

Towards Computing an Optimal Abstraction for Structural Causal Models

1 code implementation1 Aug 2022 Fabio Massimo Zennaro, Paolo Turrini, Theodoros Damoulas

Working with causal models at different levels of abstraction is an important feature of science.

Robust Bayesian Inference for Simulator-based Models via the MMD Posterior Bootstrap

1 code implementation9 Feb 2022 Charita Dellaporta, Jeremias Knoblauch, Theodoros Damoulas, François-Xavier Briol

Simulator-based models are models for which the likelihood is intractable but simulation of synthetic data is possible.

Bayesian Inference

Spatio-Temporal Variational Gaussian Processes

1 code implementation NeurIPS 2021 Oliver Hamelijnck, William J. Wilkinson, Niki A. Loppi, Arno Solin, Theodoros Damoulas

We introduce a scalable approach to Gaussian process inference that combines spatio-temporal filtering with natural gradient variational inference, resulting in a non-conjugate GP method for multivariate data that scales linearly with respect to time.

Gaussian Processes Variational Inference

Dynamic Causal Bayesian Optimization

1 code implementation NeurIPS 2021 Virginia Aglietti, Neil Dhir, Javier González, Theodoros Damoulas

This paper studies the problem of performing a sequence of optimal interventions in a causal dynamical system where both the target variable of interest and the inputs evolve over time.

Bayesian Optimization Causal Inference +2

A variational Bayesian spatial interaction model for estimating revenue and demand at business facilities

no code implementations5 Aug 2021 Shanaka Perera, Virginia Aglietti, Theodoros Damoulas

We demonstrate how BSIM outperforms competing approaches on this large dataset in terms of prediction performances while providing results that are both interpretable and consistent with related indicators observed for the London region.

Decision Making Uncertainty Quantification +1

SigGPDE: Scaling Sparse Gaussian Processes on Sequential Data

no code implementations10 May 2021 Maud Lemercier, Cristopher Salvi, Thomas Cass, Edwin V. Bonilla, Theodoros Damoulas, Terry Lyons

Making predictions and quantifying their uncertainty when the input data is sequential is a fundamental learning challenge, recently attracting increasing attention.

Gaussian Processes Time Series +2

An Expectation-Based Network Scan Statistic for a COVID-19 Early Warning System

no code implementations8 Dec 2020 Chance Haycock, Edward Thorpe-Woods, James Walsh, Patrick O'Hara, Oscar Giles, Neil Dhir, Theodoros Damoulas

One of the Greater London Authority's (GLA) response to the COVID-19 pandemic brings together multiple large-scale and heterogeneous datasets capturing mobility, transportation and traffic activity over the city of London to better understand 'busyness' and enable targeted interventions and effective policy-making.

Time Series Time Series Forecasting

Near Real-Time Social Distance Estimation in London

no code implementations7 Dec 2020 James Walsh, Oluwafunmilola Kesa, Andrew Wang, Mihai Ilas, Patrick O'Hara, Oscar Giles, Neil Dhir, Mark Girolami, Theodoros Damoulas

During the COVID-19 pandemic, policy makers at the Greater London Authority, the regional governance body of London, UK, are reliant upon prompt and accurate data sources.

Multi-task Causal Learning with Gaussian Processes

1 code implementation NeurIPS 2020 Virginia Aglietti, Theodoros Damoulas, Mauricio Álvarez, Javier González

This paper studies the problem of learning the correlation structure of a set of intervention functions defined on the directed acyclic graph (DAG) of a causal model.

Active Learning Bayesian Optimization +3

Exoplanet Validation with Machine Learning: 50 new validated Kepler planets

no code implementations24 Aug 2020 David J. Armstrong, Jevgenij Gamper, Theodoros Damoulas

Over 30% of the ~4000 known exoplanets to date have been discovered using 'validation', where the statistical likelihood of a transit arising from a false positive (FP), non-planetary scenario is calculated.

BIG-bench Machine Learning

Variational Autoencoding of PDE Inverse Problems

no code implementations28 Jun 2020 Daniel J. Tait, Theodoros Damoulas

Specifying a governing physical model in the presence of missing physics and recovering its parameters are two intertwined and fundamental problems in science.

Computational Efficiency Data Augmentation +2

Distribution Regression for Sequential Data

no code implementations10 Jun 2020 Maud Lemercier, Cristopher Salvi, Theodoros Damoulas, Edwin V. Bonilla, Terry Lyons

In this paper, we develop a rigorous mathematical framework for distribution regression where inputs are complex data streams.

regression Time Series +1

Generalized Bayesian Filtering via Sequential Monte Carlo

no code implementations23 Feb 2020 Ayman Boustati, Ömer Deniz Akyildiz, Theodoros Damoulas, Adam M. Johansen

We introduce a framework for inference in general state-space hidden Markov models (HMMs) under likelihood misspecification.

Bayesian Inference Object Tracking

Probabilistic sequential matrix factorization

1 code implementation9 Oct 2019 Ömer Deniz Akyildiz, Gerrit J. J. van den Burg, Theodoros Damoulas, Mark F. J. Steel

In particular, we consider nonlinear Gaussian state-space models where sequential approximate inference results in the factorization of a data matrix into a dictionary and time-varying coefficients with potentially nonlinear Markovian dependencies.

Multivariate Time Series Forecasting Multivariate Time Series Imputation +2

Multi-resolution Multi-task Gaussian Processes

1 code implementation NeurIPS 2019 Oliver Hamelijnck, Theodoros Damoulas, Kangrui Wang, Mark Girolami

We consider evidence integration from potentially dependent observation processes under varying spatio-temporal sampling resolutions and noise levels.

Gaussian Processes

On the Constrained Least-cost Tour Problem

no code implementations18 Jun 2019 Patrick O'Hara, M. S. Ramanujan, Theodoros Damoulas

CLT is related to the family of Travelling Salesman Problems with Profits, but differs by defining the weight function on edges instead of vertices, and by requiring the total weight to be within a range instead of being at least some quota.

Structured Variational Inference in Continuous Cox Process Models

1 code implementation NeurIPS 2019 Virginia Aglietti, Edwin V. Bonilla, Theodoros Damoulas, Sally Cripps

We propose a scalable framework for inference in an inhomogeneous Poisson process modeled by a continuous sigmoidal Cox process that assumes the corresponding intensity function is given by a Gaussian process (GP) prior transformed with a scaled logistic sigmoid function.

Numerical Integration Uncertainty Quantification +1

Non-linear Multitask Learning with Deep Gaussian Processes

no code implementations29 May 2019 Ayman Boustati, Theodoros Damoulas, Richard S. Savage

We present a multi-task learning formulation for Deep Gaussian processes (DGPs), through non-linear mixtures of latent processes.

Benchmarking Gaussian Processes +1

Doubly Robust Bayesian Inference for Non-Stationary Streaming Data with \beta-Divergences

no code implementations NeurIPS 2018 Jeremias Knoblauch, Jack E. Jewson, Theodoros Damoulas

The resulting inference procedure is doubly robust for both the predictive and the changepoint (CP) posterior, with linear time and constant space complexity.

Bayesian Inference

Doubly Robust Bayesian Inference for Non-Stationary Streaming Data with $β$-Divergences

1 code implementation NeurIPS 2018 Jeremias Knoblauch, Jack Jewson, Theodoros Damoulas

The resulting inference procedure is doubly robust for both the parameter and the changepoint (CP) posterior, with linear time and constant space complexity.

Bayesian Inference Change Point Detection

Efficient Inference in Multi-task Cox Process Models

1 code implementation24 May 2018 Virginia Aglietti, Theodoros Damoulas, Edwin Bonilla

We generalize the log Gaussian Cox process (LGCP) framework to model multiple correlated point data jointly.

Gaussian Processes Point Processes +1

Spatio-temporal Bayesian On-line Changepoint Detection with Model Selection

1 code implementation ICML 2018 Jeremias Knoblauch, Theodoros Damoulas

Bayesian On-line Changepoint Detection is extended to on-line model selection and non-stationary spatio-temporal processes.

Change Point Detection Model Selection

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