Rhetorical Structure Analysis of Japanese Patent Claims using Cue Phrases

The most important part of patent specification is where the claims are written. It is common that claims written in Japanese are described in one sentence with peculiar style and are difficult to understand for ordinary people. We are investigating NLP technologies to improve readability of patent claims. To do so, it is necessary to present the structure of patent claims in a readable way. We found that there are several typical phrases used in claim descriptions and that they can be used as clues to analyze the rhetorical structure of patent claims. We propose a method to analyze the rhetorical structure of patent claims by using these cue phrases and report the result of evaluation.