← Search

Ignavier Ng

30 accepted papers

2026

Identifying Partially Observed Causal Models from Heterogeneous/Nonstationary Data

ICML 2026poster

Estimating causal structure in the presence of latent variables is an important yet challenging problem. Recent works have shown that distributional constraints, such as rank deficiency constraints of the covariance matrices, can be exploited to recover the underlying causal structure involving late…

Cited by 0SourceScholar
2026

Learning General Causal Structures with Hidden Dynamic Process for Climate Analysis

ICML 2026poster

Understanding climate dynamics requires going beyond correlations in observational data to uncover their underlying causal process. Latent drivers, such as atmospheric processes, play a critical role in temporal dynamics, while direct causal influences also exist among geographically proximate obser…

Cited by 0SourceScholar
2026

Revisiting Differentiable Structure Learning: Inconsistency of L1 Penalty and Beyond

AAAI 2026technical

Recent advances in differentiable structure learning have framed the combinatorial problem of learning directed acyclic graphs as a continuous optimization problem. Various aspects, including data standardization, have been studied to identify factors that influence the empirical performance of thes

Cited by 0SourcePDFScholar
2026

Score-based Greedy Search for Structure Identification of Partially Observed Linear Causal Models

ICLR 2026poster

Identifying the structure of a partially observed causal system is essential to various scientific fields. Recent advances have focused on constraint-based causal discovery to solve this problem, and yet in practice these methods often face challenges related to multiple testing and error propagatio…

Cited by 0SourceScholar
2025

A General Representation-Based Approach to Multi-Source Domain Adaptation

ICML 2025poster

A central problem in unsupervised domain adaptation is determining what to transfer from labeled source domains to an unlabeled target domain. To handle high-dimensional observations (e.g., images), a line of approaches use deep learning to learn latent representations of the observations, which fac…

Cited by 0SourcePDFScholar
2025

A Skewness-Based Criterion for Addressing Heteroscedastic Noise in Causal Discovery

ICLR 2025poster

Real-world data often violates the equal-variance assumption (homoscedasticity), making it essential to account for heteroscedastic noise in causal discovery. In this work, we explore heteroscedastic symmetric noise models (HSNMs), where the effect $Y$ is modeled as $Y = f(X) + \sigma(X)N$, with $X$…

Cited by 0SourcePDFScholar
2025

Analytic DAG Constraints for Differentiable DAG Learning

ICLR 2025poster

Recovering the underlying Directed Acyclic Graph (DAG) structures from observational data presents a formidable challenge, partly due to the combinatorial nature of the DAG-constrained optimization problem. Recently, researchers have identified gradient vanishing as one of the primary obstac…

2025

Causal Representation Learning from General Environments under Nonparametric Mixing

AISTATS 2025poster

Causal representation learning aims to recover the latent causal variables and their causal relations, typically represented by directed acyclic graphs (DAGs), from low-level observations such as image pixels. A prevailing line of research exploits multiple environments, which assume how data distri…

Cited by 0SourceScholar
2025

Differentiable Causal Discovery for Latent Hierarchical Causal Models

ICLR 2025poster

Discovering causal structures with latent variables from observational data is a fundamental challenge in causal discovery. Existing methods often rely on constraint-based, iterative discrete searches, limiting their scalability for large numbers of variables. Moreover, these methods frequently assu…

Cited by 0SourcePDFScholar
2025

Latent Variable Causal Discovery under Selection Bias

ICML 2025poster

Addressing selection bias in latent variable causal discovery is important yet underexplored, largely due to a lack of suitable statistical tools: While various tools beyond basic conditional independencies have been developed to handle latent variables, none have been adapted for selection bias. We…

Cited by 0SourcePDFScholar
2025

Permutation-based Rank Test in the Presence of Discretization and Application in Causal Discovery with Mixed Data

ICML 2025poster

Recent advances have shown that statistical tests for the rank of cross-covariance matrices play an important role in causal discovery. These rank tests include partial correlation tests as special cases and provide further graphical information about latent variables. Existing rank tests typically…

2025

Synergy Between Sufficient Changes and Sparse Mixing Procedure for Disentangled Representation Learning

ICLR 2025poster

Disentangled representation learning aims to uncover the latent variables underlying observed data, yet identifying these variables under mild assumptions remains challenging. Some methods rely on sufficient changes in the distribution of latent variables indicated by auxiliary variables, such as do…

2025

When Selection Meets Intervention: Additional Complexities in Causal Discovery

ICLR 2025oral

We address the common yet often-overlooked selection bias in interventional studies, where subjects are selectively enrolled into experiments. For instance, participants in a drug trial are usually patients of the relevant disease; A/B tests on mobile applications target existing users only, and gen…

2024

A Versatile Causal Discovery Framework to Allow Causally-Related Hidden Variables

ICLR 2024poster

Most existing causal discovery methods rely on the assumption of no latent confounders, limiting their applicability in solving real-life problems. In this paper, we introduce a novel, versatile framework for causal discovery that accommodates the presence of causally-related hidden variables almost…

Cited by 17SourcePDFScholar
2024

Causal Representation Learning from Multiple Distributions: A General Setting

ICML 2024poster

In many problems, the measured variables (e.g., image pixels) are just mathematical functions of the latent causal variables (e.g., the underlying concepts or objects). For the purpose of making predictions in changing environments or making proper changes to the system, it is helpful to recover the…

Cited by 23SourcePDFScholar
2024

Federated Causal Discovery from Heterogeneous Data

ICLR 2024poster

Conventional causal discovery methods rely on centralized data, which is inconsistent with the decentralized nature of data in many real-world situations. This discrepancy has motivated the development of federated causal discovery (FCD) approaches. However, existing FCD methods may be limited by th…

2024

Gene Regulatory Network Inference in the Presence of Dropouts: a Causal View

ICLR 2024oral

Gene regulatory network inference (GRNI) is a challenging problem, particularly owing to the presence of zeros in single-cell RNA sequencing data: some are biological zeros representing no gene expression, while some others are technical zeros arising from the sequencing procedure (aka dropouts), wh…

2024

Local Causal Discovery with Linear non-Gaussian Cyclic Models

AISTATS 2024poster

Local causal discovery is of great practical significance, as there are often situations where the discovery of the global causal structure is unnecessary, and the interest lies solely on a single target variable. Most existing local methods utilize conditional independence relations, providing only…

2024

On the Parameter Identifiability of Partially Observed Linear Causal Models

NeurIPS 2024poster

Linear causal models are important tools for modeling causal dependencies and yet in practice, only a subset of the variables can be observed. In this paper, we examine the parameter identifiability of these models by investigating whether the edge coefficients can be recovered given the causal str…

2024

Score-Based Causal Discovery of Latent Variable Causal Models

ICML 2024poster

Identifying latent variables and the causal structure involving them is essential across various scientific fields. While many existing works fall under the category of constraint-based methods (with e.g. conditional independence or rank deficiency tests), they may face empirical challenges such as…

Cited by 4SourcePDFScholar
2023

Generalized Precision Matrix for Scalable Estimation of Nonparametric Markov Networks

ICLR 2023poster

A Markov network characterizes the conditional independence structure, or Markov property, among a set of random variables. Existing work focuses on specific families of distributions (e.g., exponential families) and/or certain structures of graphs, and most of them can only handle variables of a si…

Cited by 5SourcePDFScholar
2023

On the Identifiability of Sparse ICA without Assuming Non-Gaussianity

NeurIPS 2023poster

Independent component analysis (ICA) is a fundamental statistical tool used to reveal hidden generative processes from observed data. However, traditional ICA approaches struggle with the rotational invariance inherent in Gaussian distributions, often necessitating the assumption of non-Gaussianity…

Cited by 6SourcePDFScholar
2022

MissDAG: Causal Discovery in the Presence of Missing Data with Continuous Additive Noise Models

NeurIPS 2022accept

State-of-the-art causal discovery methods usually assume that the observational data is complete. However, the missing data problem is pervasive in many practical scenarios such as clinical trials, economics, and biology. One straightforward way to address the missing data problem is first to impute…

2022

On the Convergence of Continuous Constrained Optimization for Structure Learning

AISTATS 2022poster

Recently, structure learning of directed acyclic graphs (DAGs) has been formulated as a continuous optimization problem by leveraging an algebraic characterization of acyclicity. The constrained problem is solved using the augmented Lagrangian method (ALM) which is often preferred to the quadratic p…

2022

Towards Federated Bayesian Network Structure Learning with Continuous Optimization

AISTATS 2022poster

Traditionally, Bayesian network structure learning is often carried out at a central site, in which all data is gathered. However, in practice, data may be distributed across different parties (e.g., companies, devices) who intend to collectively learn a Bayesian network, but are not willing to disc…

2022

Truncated Matrix Power Iteration for Differentiable DAG Learning

NeurIPS 2022accept

Recovering underlying Directed Acyclic Graph (DAG) structures from observational data is highly challenging due to the combinatorial nature of the DAG-constrained optimization problem. Recently, DAG learning has been cast as a continuous optimization problem by characterizing the DAG constraint as a…

2021

Reliable Causal Discovery with Improved Exact Search and Weaker Assumptions

NeurIPS 2021poster

Many of the causal discovery methods rely on the faithfulness assumption to guarantee asymptotic correctness. However, the assumption can be approximately violated in many ways, leading to sub-optimal solutions. Although there is a line of research in Bayesian network structure learning that focuses…

2020

On the Role of Sparsity and DAG Constraints for Learning Linear DAGs

NeurIPS 2020poster

Learning graphical structure based on Directed Acyclic Graphs (DAGs) is a challenging problem, partly owing to the large search space of possible graphs. A recent line of work formulates the structure learning problem as a continuous constrained optimization task using the least squares objective an…