Simile or Not Simile? Automatic Detection of Metonymic Relations in Japanese Literal Comparisons

摘要

In this paper we propose a method of automatic distinction between two types of formally identical expressions in Japanese: similes and "metonymical comparisosn", i.e. literal comparisons that include metonymic relations between elements. Expression like "kujira no you na chiisai me" can be translated into English as "eyes small as whale's", while in Japanese, due to the lack of possessive case, it can be misunderstood as "eyes small as a whale". The reason behind this is the presence of metonymic relation between components of such expressions. In the abovegiven example the word "whale" is a metonymy and represents "whale's eye". This is naturally understandable for humans, although formally difficult to detect by automatic algorithms, as both types of expressions (similes and metonymical comparisons) realize the same template. In this work we present a system able to distinguish between these two types of expressions. The system takes a Japanese expression as input and uses the Internet to check possessive relations between its elements. We propose a method of calculating a score based on co-occurrence of source and target pairs in Google (e.g. "whale's eye"). Evaluation experiment showed that the system distinguishes between similes and metonimical comparisons with the accuracy of 74 %. We discuss the results and give some ideas for the future.