We can alternatively specify arc features in terms of rank-1 tensors by taking the Kronecker product of simpler feature vectors associated with the head (vector φ h ∈ R n ), and modifier (vector φ m ∈ R n ), as well as the arc itself (vector φ h,m ∈ R d ).
traditionally, parsing research has focused on modeling the direct connection between the features and the predicted syntactic relations such as head-modifier (arc) relations in dependency parsing.