In the first part, we proof that tensor product of projective semimodules is still projective; In second part, we construct the equivalence condition of projective semimodule and Horn exact sequence.

• 摘要第一部分在[3]中张量积的定义下证明了投射半模的张量积仍是投射的；第二部分在文献[4]正合列的定义下建立了投射半模与函子正合列的等价条件。