Task: Question Answering
Input (English): Then we define the similarity between INLINEFORM7 and INLINEFORM8 by, DISPLAYFORM0 We note that the similarity metric defined above for sentences is equally applicable for n-gram retrieval. 
 Question: Which similarity measure do they use in their n-gram retrieval approach?
Output (English): we define the similarity between INLINEFORM7 and INLINEFORM8 by, DISPLAYFORM0