Quasi-projective covers of right S-acts

, , ,


Abstract. In this paper S is a monoid with a left zero and AS (or A) is a
unitary right S-act. It is shown that a monoid S is right perfect (semiperfect)
if and only if every (nitely generated) strongly
at right S-act is quasiprojective.
Also it is shown that if every right S-act has a unique zero element,
then the existence of a quasi-projective cover for each right act implies that
every right act has a projective cover.


Projective, quasi-projective, perfect, semiperfect, cover. Mathematics Subject Classication [2010]: 20M30, 20M50.

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