A Study on Chinese Open-Domain Question Answering Systems
Date Issued
2004
Date
2004
Author(s)
Lin, Chuan-Jie
DOI
en-US
Abstract
Development of a question answering system focusing on open-domain knowledge in Chinese environment is studied in this dissertation. New question type categories, ranking strategies, and identification of answer candidates for short-answer questions and long-answer questions are proposed. Performances of modules in the QA system are evaluated, and the effects of different factors are studied. The NTU QA System is now working online, which receives questions and finds answers immediately from the Internet.
Questions are classified into eleven question types, including YESNO, SELECTION, PERSON, LOCATION, TIME, QUANTITY, OBJECT, METHOD, DEFINITION, PERSONDEF, and REASON questions. A classification rule set is constructed, including 136 rules with a correct rate of 72.7% in an inside test. Question cores can also be decided at the same time.
Answer candidate extractions of different question types are proposed. The candidates of short-answer questions are terms extracted by a named entity identifier or descendents in a thesaurus. Candidates of long-answer questions are phrases extracted by patterns or noun phrases with head nouns denoting persons.
Different ranking scores are proposed for different types of questions. Different Ranking strategies and weight assignments are experimented. The performances of different question types are: Coverage 52.9%, MRR 0.446 for short-answer questions; Coverage 56.3%, MRR 0.443 for DEFINITION questions; and Coverage 60.7%, MRR 0.418 for PERSONDEF questions.
An online system has been built and working on the Internet. Besides receiving questions in natural languages and returning answers found on the Internet immediately, the QA system also provides the time point when an answer took place.
Subjects
候選答案
排名策略
問句類型
開放領域
自動問答
question answering
QA
answer candidate
open domain
question type
ranking strategy
Type
thesis
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