In the active question "[Abuse of site with homework assignments](http://meta.math.stackexchange.com/questions/13374/abuse-of-site-with-homework-assignments) ", an answer was posted and very quickly deleted, together with the account of the answer author (user114176), by the Community user. 

The answer was on topic, and has score $-2$ with no upvotes. That is not low enough to cause automatic deletions (if those ever happen on answers), and Community deletions based on scores take a longer time than was the case here. The answer does not appear in the timeline of the question, its own timeline is unavailable [*edit:* by reason of non-existence] and its revision history does not indicate deletion by user votes ( <http://meta.math.stackexchange.com/posts/13438/revisions> ).

Was this a routine process such as a user-initiated account deletion or IP based sockpuppet detection, or was it something more unusual? Generally, what events can cause an answer to be listed as "deleted by Community"?

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**Update**. To summarize what has been posted,

* almost certainly a user deletion, those auto-remove negative scored answers
* up-down vote scores do not remove answers otherwise
* there is no Low Quality review queue on meta, but on the main site that can be a cause of answer deletions
* deletions by Community bot cannot be reversed by user votes to undelete