Takashi Matsuhisa. Core Equivalence in Economy for Modal Logic. In Peter M. A. Sloot, David Abramson, Alexander V. Bogdanov, Jack Dongarra, Albert Y. Zomaya, Yuri E. Gorbachev, editors, Computational Science - ICCS 2003, International Conference, Melbourne, Australia and St. Petersburg, Russia, June 2-4, 2003. Proceedings, Part II. Volume 2658 of Lecture Notes in Computer Science, pages 74-83, Springer, 2003. [doi]