Skeleton and collider characterization of Markov equivalence
= Skeleton and collider characterization of Markov equivalence
Two <Directed acyclic graphs> are <Markov equivalent directed acyclic graphs> if and only if they have the same <skeleton of a directed graph> and the same <unshielded colliders>. Thus these two structures determine the observational equivalence class. This structural theorem is what converts the skeleton and collider phases of the <PC algorithm> into identification of an equivalence class.