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Learning Sparse Causal Models is not NP-hard
Proceedings of the 29th Conference on Uncertainty in Artificial Intelligence, PMLR R11:75-84, 2013.
Abstract
This paper shows that causal model discov- ery is not an NP-hard problem, in the sense that for sparse graphs bounded by node de- gree k the sound and complete causal model can be obtained in worst case order N 2(k+2) independence tests, even when latent vari- ables and selection bias may be present. We present a modification of the well-known FCI algorithm that implements the method for an independence oracle, and suggest improve- ments for sample/real-world data versions. It does not contradict any known hardness re- sults, and does not solve an NP-hard prob- lem: it just proves that sparse causal discov- ery is perhaps more complicated, but not as hard as learning minimal Bayesian networks.