This system was developed by me and my students at Kyushu Institute of Technology and was supported by AITEC. Sousuke Kaneko and Kouji Yamauchi made great contributions to this project. Kaneko implemented the tokenizer and the parser, and Yamauchi wrote several example programs and gave me constructive feedback about the design of DJ even before I started to implement the system. I am also grateful to Isao Nagasawa, Masanobu Umeda, Drew McDermott and Shouji He for helpful discussions.