Operator theoretic measures of causality from linearised dynamics

Fuente: arXiv
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Autori principali: Srivastava, Ankit, Cattafesta, Louis, Dawson, Scott
Natura: Preprint
Pubblicazione: 2025
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author Srivastava, Ankit
Cattafesta, Louis
Dawson, Scott
author_facet Srivastava, Ankit
Cattafesta, Louis
Dawson, Scott
contents This paper presents an operator-theoretic framework Linear Operator Causality Analysis (LOCA), for analysing causality in linearised dynamical systems, focusing here on fluid flows. We demonstrate that the matrix exponential of the linearised differential equations fundamentally encodes the causal relationships between system modes at any future time. We further develop a global measure of causality that quantifies the presence and extent of global causality across all time horizons. This approach provides a physics-based alternative to statistical and information-theoretic causality measures such as Granger causality and transfer entropy. Unlike these data-driven techniques that infer causality from time-series data, LOCA leverages the linearised governing equations, yielding a more rigorous and interpretable measure of causal interactions. We show that LOCA gives equivalent results to data-driven methods under certain assumptions, and further discuss connections to key system properties such as controllability, observability, and graph-theoretic transitive closure. To complement this operator-based approach, we introduce a data-driven methodology akin to Dynamic Mode Decomposition (DMD) that estimates causal connections directly from time series data by approximating the matrix exponential. LOCA also mitigates common issues in data-driven causality analyses, such as misleading inferences due to correlated variables or state truncation. We demonstrate our method on linearised Couette flow, demonstrating how our framework captures both direct and indirect causal interactions among flow structures. Through this example, we highlight the advantages of our approach, including its robustness to correlation-induced biases and its ability to identify causally significant modes.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08118
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Operator theoretic measures of causality from linearised dynamics
Srivastava, Ankit
Cattafesta, Louis
Dawson, Scott
Chaotic Dynamics
Mathematical Physics
This paper presents an operator-theoretic framework Linear Operator Causality Analysis (LOCA), for analysing causality in linearised dynamical systems, focusing here on fluid flows. We demonstrate that the matrix exponential of the linearised differential equations fundamentally encodes the causal relationships between system modes at any future time. We further develop a global measure of causality that quantifies the presence and extent of global causality across all time horizons. This approach provides a physics-based alternative to statistical and information-theoretic causality measures such as Granger causality and transfer entropy. Unlike these data-driven techniques that infer causality from time-series data, LOCA leverages the linearised governing equations, yielding a more rigorous and interpretable measure of causal interactions. We show that LOCA gives equivalent results to data-driven methods under certain assumptions, and further discuss connections to key system properties such as controllability, observability, and graph-theoretic transitive closure. To complement this operator-based approach, we introduce a data-driven methodology akin to Dynamic Mode Decomposition (DMD) that estimates causal connections directly from time series data by approximating the matrix exponential. LOCA also mitigates common issues in data-driven causality analyses, such as misleading inferences due to correlated variables or state truncation. We demonstrate our method on linearised Couette flow, demonstrating how our framework captures both direct and indirect causal interactions among flow structures. Through this example, we highlight the advantages of our approach, including its robustness to correlation-induced biases and its ability to identify causally significant modes.
title Operator theoretic measures of causality from linearised dynamics
topic Chaotic Dynamics
Mathematical Physics
url https://arxiv.org/abs/2506.08118