| In this paper we give three equational systems of commutative BCK-algebra. The first system CBKⅠconsists of the following three identities: ((x·y)·(x·z))·(z·y)=0,x·0=x,x·(x·y)=y·(y·x).The second system CBK Ⅱ consists of the following three identities:0·x=0,x·0=x,(x·y)·(x·z)=(z·y)·(z·x).The third system CBKⅢ consists of the following three identities: x·x=0,x·0=x,(x·y)·(x·z)=(z·y)·(z·x). |
