http://r6.ca/blog/20110930T012533Z.html
He posted his work to the arXiv under a public domain dedication; the ACM refused to publish it because of its copyright status. (I think Russell O'Connor is a MO member; perhaps he is reading this?)
Of course, you might say he brought it on himself by being so fussy about copyright issues. If he had posted to arxiv under the standard license, it would probably be ok (maybe). Certainly, if he hadn't bothered to mention the copyright status of his paper, and just signed the copyright transfer, the ACM would publish it no questions asked. (If only editors are involved, there's surely no problem; if lawyers get involved, things change.)
There is a definitely a grey area separating the usual practice (arXiv is fine!) with official policy; although the usual practice usually prevails, it's not obvious to me that it does so in every case.
]]>Question got reopened. I voted to reclose. I would have voted to close it also couple month ago, but now there is the already mentioned mathforge board and academia.SE (in public beta AFAIK), so really no reason to have this on MO.
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