The remainder of the chapter introduces three predominant instantiations of syntax-based models: hierarchical phrase-based SMT (Hiero) (Chiang 2007) , which is a non-labeled syntax-based SMT approach arising from the phrase-based approach; syntax-augmented machine translation (SAMT), which introduces the notion of soft labels while keeping the nonlinguistic phrase notion; and GHKM <cite>(Galley et al. 2004</cite> ), which only extracts translation rules consistent with constituency parse subtrees.