Talk:Projective cover
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General stuff
[edit]"Lift/rad rings can be characterized: R is lift/rad if and only if eR has a projective cover, for every idempotent e in R."
I think this is false, because, if e is an idempotent of R, then eR is always a direct summand of R, hence projective, so it has a projective cover (namely itself). (unsigned comment 15:08, 22 May 2011 92.224.254.58)
I wondered why that lift/rad thing was dangling there: the conclusion had been severed. I put the correct conclusion in with an appropriate reference, so there should be no issue now. Rschwieb (talk) 19:20, 7 July 2011 (UTC)
Category theorists help?
[edit]I was just noticing that the article describes what a superfluous epimorphism is in the category of modules, but omits it for general categories. I couldn't think of a categorical definition for a superfluous subobject, so I wonder if someone could clarify or decide if some restriction needs to be made. Rschwieb (talk) 19:24, 7 July 2011 (UTC)