Relaxing Faithfulness with Intervention-Only Causal Discovery
Summary
A new causal discovery framework, "Relaxing Faithfulness with Intervention-Only Causal Discovery," addresses limitations of traditional algorithms that rely on the "faithfulness" assumption. This assumption, requiring statistical dependence for causally linked variables, is often violated by "path cancellation" in natural systems, leading to incorrect causal structure identification. The authors introduce "intervention immediacy (II) faithfulness," a significantly milder assumption that tolerates such cancellations. This framework re-prioritizes "hard interventions" as the primary carriers of causal information, moving away from conditional independence (CI) testing. Two algorithms, Unrestricted Intervention Cardinality (UIC) and k-Restricted Intervention Cardinality (k-RIC), are proposed. UIC identifies the true graph using O(n^2) interventions of cardinality up to n-1. k-RIC identifies the graph up to its k-robust transitive closure when intervention cardinality is limited. Empirical validation on 10-node synthetic DAGs shows k-RIC, particularly with k=2 and CI-refinement, achieves an average Structural Hamming Distance (SHD) of 4-6, outperforming CI-based baselines like PC->Interv and IGSP by approximately half.
Key takeaway
For Research Scientists and Machine Learning Engineers designing causal discovery experiments, especially in fields like cell biology where hard interventions are feasible, you should prioritize intervention-based methods over traditional conditional independence tests. This approach, leveraging "intervention immediacy faithfulness," robustly identifies causal structures even in systems with path cancellation. Implement multi-node interventions (e.g., k=2) and a CI-refinement step to achieve significantly higher accuracy, reducing structural Hamming distance by approximately half compared to CI-first baselines.
Key insights
Intervention-only causal discovery, using "intervention immediacy faithfulness," robustly identifies causal structures by prioritizing hard interventions over conditional independence tests.
Principles
- Path cancellation violates standard faithfulness assumptions.
- Hard interventions reveal causal links directly.
- II faithfulness is parametrically milder than CI faithfulness.
Method
Algorithms perform single-node interventions to build a transitive closure. Edges are then pruned by testing if endpoints are conditional Most Immediate Children (MICs) given other parents or minimum vertex cuts, using hard interventions.
In practice
- Prioritize hard interventions for causal structure learning.
- Employ multi-node interventions for better accuracy.
- Refine intervention-derived graphs with CI tests.
Topics
- Causal Discovery
- Hard Interventions
- Faithfulness Assumption
- Path Cancellation
- Structural Causal Models
- k-RIC Algorithm
Code references
Best for: AI Scientist, Machine Learning Engineer, Research Scientist
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Editorial summary, takeaway, and curation by AIssential. Original article published by stat.ML updates on arXiv.org.