In this article the general theory of Commutative BCK-algebras and BCI-algebras and several classes of BCK-algebras are given according to [2].
@article{bwmeta1.element.doi-10_2478_v10037-007-0027-2, author = {Tao Sun and Dahai Hu and Xiquan Liang}, title = {Several Classes of BCK-algebras and their Properties}, journal = {Formalized Mathematics}, volume = {15}, year = {2007}, pages = {237-242}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_2478_v10037-007-0027-2} }
Tao Sun; Dahai Hu; Xiquan Liang. Several Classes of BCK-algebras and their Properties. Formalized Mathematics, Tome 15 (2007) pp. 237-242. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_2478_v10037-007-0027-2/
[1] Yuzhong Ding. Several classes of BCI-algebras and their properties. Formalized Mathematics, 15(1):1-9, 2007.
[2] Jie Meng and YoungLin Liu. An Introduction to BCI-algebras. Shaanxi Scientific and Technological Press, 2001.
[3] Zinaida Trybulec. Properties of subsets. Formalized Mathematics, 1(1):67-71, 1990.