NTCIR-7 Patent Mining Experiments at Hitachi.

This paper reports results of our experiments on the automatic assignment of patent classification to research paper abstracts. We applied K-Nearest Neighbors Methods and three kinds of query term expansion methods using a research paper abstract dataset and a patent document dataset to improve the classification accuracy. The results show that these query expansion methods slightly improve classification accuracy when the parameter is tuned appropriately. We also compared the classification accuracy when research paper abstracts are used as input with that when abstracts or full texts of patent documents are used as input.