For example, assuming that the gold segmentation of the sentence in Figure 1 is "x 1 |x 2 |x 3 x 4 x 5 (= w 1 |w 2 |w 8 )", candidate words for all characters contain their gold words, and those for characters x 1 and x 2 consist only of respective gold words w 1 and w 2 .
the upper and lower bounds for the sentence are 5/5 and 2/5, respectively.