Take Figure 2 as an example, following the Direct Projection Algorithm (DPA) (Hwa et al., 2005) (Section 5), the dependency relationships between words can be directly projected from the source Algorithm 2 Training projection model ∇φ ← grad(DP , DN , φ(λ)) 4: λ ← climb(φ, ∇φ, λ) 5: until maximization language to the target language.
we can hardly obtain a treebank with complete trees through direct projection.