H L , H R are respectively H's left dependents and right dependents, plus EOC (End-Of-Children), a special token to inform that there are no more dependents to generate.
p (d(ROOT )) is the probability of generating the entire dependency structure d. Le and Zuidema's ∞-order generative model is defined as Eisner's model in which the context C ∞ (D) to generate D contains all of D's generated siblings, its ancestors and their siblings.