Abstract
Let S be a semigroup. In this paper, projective S-acts and exact sequences in S-Act are studied. It is shown that, for a unitary S-act P, the functor Hom(P, –) is exact if and only if P ≅ Se for some idempotent e ɛ S.
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Communicated by K.P. Shum
The research was supported by the National Natural Science Foundation of China.
1991 Mathematics Subject Classification: 20M50
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Chen, Y. Projective S-acts and Exact Functors. Algebra Colloq. 7, 113–120 (2000). https://doi.org/10.1007/s10011-000-0113-2
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DOI: https://doi.org/10.1007/s10011-000-0113-2