Let $P$ be a module in an abelian category $\mathcal C$ satisfying $Ext(P,M)=0$ for all modules $M \in \mathcal C$.
Can we conclude that $P$ is projective? Any reference for this?
Let $P$ be a module in an abelian category $\mathcal C$ satisfying $Ext(P,M)=0$ for all modules $M \in \mathcal C$.
Can we conclude that $P$ is projective? Any reference for this?
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