Identification for Tree-shaped Structural Causal Models in Polynomial Time

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Autori principali: Gupta, Aaryan, Bläser, Markus
Natura: Preprint
Pubblicazione: 2023
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author Gupta, Aaryan
Bläser, Markus
author_facet Gupta, Aaryan
Bläser, Markus
contents Linear structural causal models (SCMs) are used to express and analyse the relationships between random variables. Direct causal effects are represented as directed edges and confounding factors as bidirected edges. Identifying the causal parameters from correlations between the nodes is an open problem in artificial intelligence. In this paper, we study SCMs whose directed component forms a tree. Van der Zander et al. (AISTATS'22, PLMR 151, pp. 6770--6792, 2022) give a PSPACE-algorithm for the identification problem in this case, which is a significant improvement over the general Gröbner basis approach, which has doubly-exponential time complexity in the number of structural parameters. In this work, we present a randomized polynomial-time algorithm, which solves the identification problem for tree-shaped SCMs. For every structural parameter, our algorithms decides whether it is generically identifiable, generically 2-identifiable, or generically unidentifiable. (No other cases can occur.) In the first two cases, it provides one or two fractional affine square root terms of polynomials (FASTPs) for the corresponding parameter, respectively.
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id arxiv_https___arxiv_org_abs_2311_14058
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publishDate 2023
record_format arxiv
spellingShingle Identification for Tree-shaped Structural Causal Models in Polynomial Time
Gupta, Aaryan
Bläser, Markus
Artificial Intelligence
Data Structures and Algorithms
Linear structural causal models (SCMs) are used to express and analyse the relationships between random variables. Direct causal effects are represented as directed edges and confounding factors as bidirected edges. Identifying the causal parameters from correlations between the nodes is an open problem in artificial intelligence. In this paper, we study SCMs whose directed component forms a tree. Van der Zander et al. (AISTATS'22, PLMR 151, pp. 6770--6792, 2022) give a PSPACE-algorithm for the identification problem in this case, which is a significant improvement over the general Gröbner basis approach, which has doubly-exponential time complexity in the number of structural parameters. In this work, we present a randomized polynomial-time algorithm, which solves the identification problem for tree-shaped SCMs. For every structural parameter, our algorithms decides whether it is generically identifiable, generically 2-identifiable, or generically unidentifiable. (No other cases can occur.) In the first two cases, it provides one or two fractional affine square root terms of polynomials (FASTPs) for the corresponding parameter, respectively.
title Identification for Tree-shaped Structural Causal Models in Polynomial Time
topic Artificial Intelligence
Data Structures and Algorithms
url https://arxiv.org/abs/2311.14058