In this paper, we proved that the definition of a semilattice as a universalalgebra and the definition of a semilattice as a partial ordered set are equivalent.
本文中，我们证明了作为泛代数的半格的定义与作为偏序集的半格的定义是等价的。
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The concept direct products of BCI-Algebra by using the universal property is introduced and uniqueness and existence of direct products of BCI-Alegbra are also proved.