TY - JOUR T1 - On Direct Sum of Branches in Hyper BCK-algebras TT - JF - IJMSI JO - IJMSI VL - 11 IS - 2 UR - http://ijmsi.ir/article-1-441-en.html Y1 - 2016 SP - 43 EP - 55 KW - Hyper BCK-algebra KW - (weak KW - strong) hyper BCK-ideal KW - Direct sum of branches KW - Hyper BCK-chain. N2 - In this paper, the notion of direct sum of branches in hks is introduced and some related properties are investigated. Applying this notion to lower hyper $BCK$-semi lattice, a necessary condition for a hi to be prime is given. Some properties of hkc are studied. It is proved that if $H$ is a hkc and $[a)$ is finite for any $ain H$, then $mid Aut(H)mid=1$. M3 10.7508/ijmsi.2016.02.003 ER -