Fuzzy implicative ideals of BCK-algebras

The notion of fuzzy implicative ideals of BCK-algebras is introduced. The following results are obtained: for a BCK-algebra X, and fuzzy ideal μ of X must be a fuzzy subalgebra of X; suppose that μ and v are fuzzy ideals of X with μ ⪕ v and μ(0) = v(0); if μ is a fuzzy implicative ideal of X the so is v; a fuzzy ideal μ of X is fuzzy implicative if and only if μ is both fuzzy positive implicative and fuzzy commutative; a BCK-algebra X is implicative (resp. positive implicative, commutative) if and only if every fuzzy ideal of X is fuzzy implicative (resp. fuzzy positive implicative, fuzzy commulative). Also, several characterizations of fuzzy implicative ideals are given.