🤖 AI Summary
Traditional cluster-DAGs (C-DAGs) impose partition admissibility—requiring variable clustering to yield an acyclic C-DAG—severely limiting applicability in complex systems. This work breaks that restriction by introducing *cyclic C-DAGs*, which admit arbitrary variable clusterings, including those inducing cycles. To support sound causal reasoning under cyclicity, we reformulate d-separation for clustered variables, extend the do-calculus with cluster-level inference rules, and establish a complete and sound framework for cluster-level causal identification. We prove that the framework correctly identifies all cluster-intervention effects that are causally identifiable from the underlying causal graph. Empirical evaluation demonstrates that cyclic C-DAGs significantly broaden the scope of C-DAGs in macro-scale modeling, modular system analysis, and multi-scale causal inference, thereby providing a rigorous foundation for higher-order causal abstraction.
📝 Abstract
Cluster DAGs (C-DAGs) provide an abstraction of causal graphs in which nodes represent clusters of variables, and edges encode both cluster-level causal relationships and dependencies arisen from unobserved confounding. C-DAGs define an equivalence class of acyclic causal graphs that agree on cluster-level relationships, enabling causal reasoning at a higher level of abstraction. However, when the chosen clustering induces cycles in the resulting C-DAG, the partition is deemed inadmissible under conventional C-DAG semantics. In this work, we extend the C-DAG framework to support arbitrary variable clusterings by relaxing the partition admissibility constraint, thereby allowing cyclic C-DAG representations. We extend the notions of d-separation and causal calculus to this setting, significantly broadening the scope of causal reasoning across clusters and enabling the application of C-DAGs in previously intractable scenarios. Our calculus is both sound and atomically complete with respect to the do-calculus: all valid interventional queries at the cluster level can be derived using our rules, each corresponding to a primitive do-calculus step.