LR-Hiero uses a constrained lexicalized SCFG which we call a GNF grammar: X → γ,b β where γ is a string of non-terminal and terminal symbols,b is a string of terminal symbols and β is a possibly empty sequence of non-terminals. This ensures that as each rule is used in a derivation, Add h to hypList 29: return hypList the target string is generated from left to right. The rules are obtained from a word and phrase aligned bitext using the rule extraction algorithm in<cite> (Watanabe et al., 2006)</cite> .