02 2012 档案
摘要:Chapter8 Analyzing Sentence Structure 分析句子结构 Earlier chapters focused on words: how to identify them, analyze their structure, assign them to lexical categories, and access their meanings. We have also seen how to identify patterns in word sequences or n-grams. However, these methods only scratch ..
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摘要:7.8Further Reading Extra materials for this chapter are posted at http://www.nltk.org/, including links to freely available resources on the web. For more examples of chunking with NLTK, please see the Chunking HOWTO at http://www.nltk.org/howto. The popularity of chunking is due in great part to ..
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摘要:7.9Exercises 练习 ☼ The IOB format categorizes tagged tokens as I, O and B. Why are three tags necessary? What problem would be caused if we used I and O tags exclusively? ☼ Write a tag pattern to match noun phrases containing plural head nouns, e.g. "many/JJ researchers/NNS",...
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摘要:7.7Summary 小结 Information extraction systems search large bodies of unrestricted text for specific types of entities and relations, and use them to populate well-organized databases. These databases can then be used to find answers for specific questions. The typical architecture...
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摘要:7.6Relation Extraction 关系抽取 Once named entities have been identified in a text, we then want to extract the relations that exist between them. As indicated earlier, we will typically be looking for relations between specified types of named entity. One way of approaching this task is to initially l.
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