gaussianVanishingIdeal(R,G,OldVersion=>false)
By default, gaussianVanishingIdeal uses the code of the current version. However, if the graph only has directed edges, the user can choose to use the code from the previous version which is based on (2) from Seth Sullivant, Kelli Talaska, and Jan Draisma, Trek separation for Gaussian graphical models, The Annals of Statistics 38.3 (2010): 1665-1685.