Automatic generation of English/Chinese thesaurus based on a parallel corpus in laws
Authors: Yang Christopher C. , Luk Johnny 
Published: April 2003

The information available in languages other than English in the World Wide Web is increasing significantly. According to a report from Computer Economics in 1999, 54% of Internet users are English speakers (“English Will Dominate Web for Only Three More Years,”Computer Economics, July 9,1999,http://www.computereconomics.com/new4/pr/pr990610.html). However, it is predicted that there will be only 60% increase in Internet users among English speakers verses a 150% growth among non‐English speakers for the next five years. By 2005, 57% of Internet users will be non‐English speakers. A report by CNN.com in 2000 showed that the number of Internet users in China had been increased from 8.9 million to 16.9 million from January to June in 2000 (“Report: China Internet users double to 17 million,”CNN.com, July,2000,http://cnn.org/2000/TECH/computing/07/27/china.internet.reut/index.html). According to Nielsen/NetRatings, there was a dramatic leap from 22.5 millions to 56.6 millions Internet users from 2001 to 2002. China had become the second largest global at‐home Internet population in 2002 (US's Internet population was 166 millions) (Robyn Greenspan, “China Pulls Ahead of Japan,” Internet.com, April 22,2002,http://cyberatlas.internet.com/big_picture/geographics/article/0,,5911_1013841,00.html). All of the evidences reveal the importance of cross‐lingual research to satisfy the needs in the near future.

Digital library research has been focusing in structural and semantic interoperability in the past. Searching and retrieving objects across variations in protocols, formats and disciplines are widely explored (Schatz, B., & Chen, H. (1999). Digital libraries: technological advances and social impacts. IEEE Computer, Special Issue on Digital Libraries, February, 32(2), 45–50.; Chen, H., Yen, J., & Yang, C.C. (1999). International activities: development of Asian digital libraries. IEEE Computer, Special Issue on Digital Libraries, 32(2), 48–49.). However, research in crossing language boundaries, especially across European languages and Oriental languages, is still in the initial stage. In this proposal, we put our focus oncross‐lingual semantic interoperabilityby developing automatic generation of a cross‐lingual thesaurus based on English/Chinese parallel corpus. When the searchers encounter retrieval problems, professional librarians usually consult the thesaurus to identify other relevant vocabularies. In the problem of searching across language boundaries, a cross‐lingual thesaurus, which is generated by co‐occurrence analysis and Hopfield network, can be used to generate additional semantically relevant terms that cannot be obtained from dictionary. In particular, the automatically generated cross‐lingual thesaurus is able to capture the unknown words that do not exist in a dictionary, such as names of persons, organizations, and events. Due to Hong Kong's unique history background, both English and Chinese are used as official languages in all legal documents. Therefore, English/Chinese cross‐lingual information retrieval is critical for applications in courts and the government. In this paper, we develop an automatic thesaurus by the Hopfield network based on a parallel corpus collected from the Web site of the Department of Justice of the Hong Kong Special Administrative Region (HKSAR) Government. Experiments are conducted to measure the precision and recall of the automatic generated English/Chinese thesaurus. The result shows that such thesaurus is a promising tool to retrieve relevant terms, especially in the language that is not the same as the input term. The direct translation of the input term can also be retrieved in most of the cases.