What it says in the title. The following question has been posted (at least) twice:
First order logic equivalence proof
Each time the OP engages for a short bit, then deletes the question. My question is: what should I do about this? Do I flag an instance as it arises? Do I undelete the original and vote to close the others as duplicates? (Note that the user in question is not registered, so appears as a different username in each posting.)
EDIT: Three times, this one's still up:
I've added a comment asking the user to stop doing this. Should I still flag?