Membership Testing in Markov Equivalence Classes via Independence Query Oracles

Fuente: arXiv
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Hauptverfasser: Zhang, Jiaqi, Shiragur, Kirankumar, Uhler, Caroline
Format: Preprint
Veröffentlicht: 2024
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author Zhang, Jiaqi
Shiragur, Kirankumar
Uhler, Caroline
author_facet Zhang, Jiaqi
Shiragur, Kirankumar
Uhler, Caroline
contents Understanding causal relationships between variables is a fundamental problem with broad impact in numerous scientific fields. While extensive research has been dedicated to learning causal graphs from data, its complementary concept of testing causal relationships has remained largely unexplored. While learning involves the task of recovering the Markov equivalence class (MEC) of the underlying causal graph from observational data, the testing counterpart addresses the following critical question: Given a specific MEC and observational data from some causal graph, can we determine if the data-generating causal graph belongs to the given MEC? We explore constraint-based testing methods by establishing bounds on the required number of conditional independence tests. Our bounds are in terms of the size of the maximum undirected clique ($s$) of the given MEC. In the worst case, we show a lower bound of $\exp(Ω(s))$ independence tests. We then give an algorithm that resolves the task with $\exp(O(s))$ tests, matching our lower bound. Compared to the learning problem, where algorithms often use a number of independence tests that is exponential in the maximum in-degree, this shows that testing is relatively easier. In particular, it requires exponentially less independence tests in graphs featuring high in-degrees and small clique sizes. Additionally, using the DAG associahedron, we provide a geometric interpretation of testing versus learning and discuss how our testing result can aid learning.
format Preprint
id arxiv_https___arxiv_org_abs_2403_05759
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Membership Testing in Markov Equivalence Classes via Independence Query Oracles
Zhang, Jiaqi
Shiragur, Kirankumar
Uhler, Caroline
Machine Learning
Artificial Intelligence
Methodology
Understanding causal relationships between variables is a fundamental problem with broad impact in numerous scientific fields. While extensive research has been dedicated to learning causal graphs from data, its complementary concept of testing causal relationships has remained largely unexplored. While learning involves the task of recovering the Markov equivalence class (MEC) of the underlying causal graph from observational data, the testing counterpart addresses the following critical question: Given a specific MEC and observational data from some causal graph, can we determine if the data-generating causal graph belongs to the given MEC? We explore constraint-based testing methods by establishing bounds on the required number of conditional independence tests. Our bounds are in terms of the size of the maximum undirected clique ($s$) of the given MEC. In the worst case, we show a lower bound of $\exp(Ω(s))$ independence tests. We then give an algorithm that resolves the task with $\exp(O(s))$ tests, matching our lower bound. Compared to the learning problem, where algorithms often use a number of independence tests that is exponential in the maximum in-degree, this shows that testing is relatively easier. In particular, it requires exponentially less independence tests in graphs featuring high in-degrees and small clique sizes. Additionally, using the DAG associahedron, we provide a geometric interpretation of testing versus learning and discuss how our testing result can aid learning.
title Membership Testing in Markov Equivalence Classes via Independence Query Oracles
topic Machine Learning
Artificial Intelligence
Methodology
url https://arxiv.org/abs/2403.05759