Figure 10 .17 A sample alignment between sentences in English and French, with sentences extracted from Antoine de Saint-Exupery's Le Petit Prince and a hypothetical translation. Sentence alignment takes sentences e 1 , ..., e n , and f 1 , ..., f n and finds minimal sets of sentences that are translations of each other, including single sentence mappings like (e 1 ,f 1 ), (e 4 -f 3 ), (e 5 -f 4 ), (e 6 -f 6 ) as well as 2-1 alignments (e 2 /e 3 ,f 2 ), (e 7 /e 8 -f 7 ), and null alignments (f 5 ).