2. The information processing apparatus according to claim 1 , wherein the processor classifies the document by: obtaining a list of keywords capable of specifying the first category, and classifying the document into the first category, when the document contains the word that matches any of the keywords.
1. An information processing apparatus comprising: a memory; and a processor, which: receives instructions from a user to search for a document; searches for the document in a storage associated with the information processing apparatus; stores the document in the memory; classifies the document into a first category and a second category; extracts a word from the document; determines a first total number of documents in the first category; determines a second total number of documents in the second category; determines a first number of documents as a first count of the documents in the first category that contain the word; determines a second number of the documents as a second count of the documents in the second category that contain the word; determines a first ratio of the first total number of documents and the first number of documents; determines a second ratio of the second total number of documents and the second number of documents; calculates a word score for the word using a mathematical product of the first ratio and the second ratio, wherein the word score is higher when the word appears less frequently in the category; extracts a sentence from the document; calculates a sentence score for the sentence on the basis of the word score; and displays the sentence on a display, when the sentence score exceeds a threshold.