Observe that our transformation does not cause nonterminals which were linked in the original grammar to become unlinked, as noted for example in Figure 4.
subtrees which are gener-  76 14 66% 1.47 ITG (10000 translation pairs) 10,003 170,000 99.97% 1.31 Table 1: Grammar sizes before and after prefix lexicalization, showing O(n 2 ) size increase instead of the worst case O(n 3 ).