PLSI Utilization for Automatic Thesaurus Construction Masato Hagiwara author Yasuhiro Ogawa author Katsuhiko Toyama author 2005 text Second International Joint Conference on Natural Language Processing: Full Papers conference publication hagiwara-etal-2005-plsi 10.1007/11562214_30 https://aclanthology.org/I05-1030/ 2005