참고문헌
- Y. Huang, BCI-algebra, Science Press, Beijing, 2006.
- Y. B. Jun and S. Z. Song, Subalgebras and closed ideals of BCH-algebras based on bipolar-valued fuzzy sets, Sci. Math. Jpn. 68 (2008), no. 2, 287-297.
- K. J. Lee, Bipolar fuzzy subalgerbas and bipolar fuzzy ideals of BCK/BCI-algerbas, Bull. Malays. Math. Sci. Soc. (in press).
- K. M. Lee, Bipolar-valued fuzzy sets and their operations, Proc. Int. Conf. on Intelligent Technologies, Bangkok, Thailand (2000), 307-312.
- K. M. Lee, Comparison of interval-valued fuzzy sets, intuitionistic fuzzy sets, and bipolar-valued fuzzy sets, J. Fuzzy Logic Intelligent Systems 14 (2004), no. 2, 125-129.
- J. Meng and Y. B. Jun, BCK-algebras, Kyungmoon Sa Co. Seoul, 1994.