The point when studying bifuzzy mathematics lies in how to carry out the ordinary concept to bifuzzy case. In other words, how to pick out the ordered pair of the rational generalization from the large ordered pairs available. The bifuzzy sets are featured by an additional degree, which is called the degree of uncertainty. This book aims to introduce a new notion of bifuzzy implicative ideals in BCK-algebras and various properties of these notions in the context of bifuzzy sets established. This book also redefined BCI - implicative ideals of BCI - algebra and studied the foldness theory of fuzzy BCI - implicative ideals in BCI-algebras. Finally, we construct some algorithms for analyzing the fuzzy and bifuzzy theory of subset in BCK/BCI- algebras.