Calculating Tetrad constraints implied by directed acyclic graphs Peter Spirtes 10.1184/R1/6491036.v1 https://kilthub.cmu.edu/articles/journal_contribution/Calculating_Tetrad_constraints_implied_by_directed_acyclic_graphs/6491036 Department of Philosophy technical report 1990-01-01 00:00:00 Computer simulation. Mathematical statistics.