During the last two and a half years since I became a member of the SE community, it has happened so many times that my questions have been marked as duplicate, especially during the first few months of my activity here. Although I've somehow managed to cut down on the number of duplicate questions I ask here, I'm still unable to ensure this never happens again.

Is there a fool-proof method to avoid duplication in one's questions (and answers) on SE? A couple of weeks ago, @Brian M. Scott caught out one of my duplicate questions, to my immense surprise! I wondered how he managed to track down the duplication!

N.B. I'm not sure which tag to put on this question; so I've just used the reference-request tag.

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    $\begingroup$ Good of you to ask (+1). The problem is persistent, so not unexpectedly it has been discussed before. For example here. My superficial understanding/advice is that google is better at it than the on-site search engine (largely because the latter cannot handle TeX at all). $\endgroup$ Apr 27, 2015 at 5:22
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    $\begingroup$ So, in other words, this question about avoiding duplications is a duplicate. $\endgroup$ Apr 27, 2015 at 6:23
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    $\begingroup$ Currently, 16 of your 285 non-deleted questions are marked as duplicate. That's not an alarming percentage. As long as you keep on searching for duplicates before you ask, everything is fine. If you don't find a duplicate although the question has been asked before, chances are that your way of writing it is different enough that future searchers now have a higher probability of finding the question, either your version or the other. Having a few duplicates, as long as all are well-asked, and they are formulated differently, is actually a good thing: easier to find for the next asker. $\endgroup$ Apr 27, 2015 at 9:22
  • $\begingroup$ @DanielFischer, how were you able to spot how many of my questions have been marked as duplicate? Have you actually counted them? $\endgroup$ Apr 27, 2015 at 17:24
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    $\begingroup$ Search: user:59734 is:q duplicate:1 (for one's own posts, user:me works and means one need not remember one's user number). That returned 16 results. You don't have so many posts, hence manual counting would be doable, but letting the system count is faster. $\endgroup$ Apr 27, 2015 at 17:29
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    $\begingroup$ I'm quoting Asaf Karagila here, "Wouldn't it be deliciously ironic if this is a duplicate as well?" ;)...Oh this must be duplicate comment...So this is a duplicate comment on a duplicate meta post about duplicate posts. Duplicate-ception! $\endgroup$
    – Zach466920
    Apr 28, 2015 at 17:52
  • $\begingroup$ Google search sometimes seems to work better than the onsite search here. That's how I've found some questions on here. $\endgroup$
    – user153918
    Apr 29, 2015 at 17:20

1 Answer 1


The bad news is that there is no foolproof way to find duplicates. The good news is that the standard for being a good community member is not perfection. It sounds like you're making an effort to avoid posting duplicates and, moreover, like you've gotten better. I don't think anyone can ask you to do more.

That said, if you're really intent on finding duplicates, you might try:

  • Look through the list of "Questions that may already have your answer" after titling and tagging your question - the system seems to use those pieces of data more than the body of your question. This seems to work better than most methods

  • Search the site for related keywords. For instance, I might search "abelian cyclic" searching for an answer for your question here. It didn't bring any duplicate up this time, but sometimes you get lucky - especially if you try various combinations of keywords.

  • As suggested in comments, you can always try Googling the site by adding "site:math.stackexchange.com" to a Google query.

But, ultimately, the question asker is not in an ideal position to find a duplicate. Highly active community members likely have a broader knowledge of the subject than you and certainly have a greater familiarity with the sort of questions that get posted to the site - and that's really helpful to finding duplicates.

I might suggest, that Brian M. Scott found that your question here was a duplicate of this one here because he wrote an answer to the latter one. It's really easy to find a duplicate when you know you already wrote an answer - and sometimes, that's the only way you'll ever find the duplicate.

  • $\begingroup$ Yep. In fact the moment I type site into Firefox’s search window I get a boatload of dropdown suggests of the form [keywords] brian site:math.stackexchange.com, which tells you something about how often I’ve done such searches! $\endgroup$ May 2, 2015 at 2:20
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    $\begingroup$ Even without specifying site:math.stackexchange.com I often find questions here in the very first page of Google results. First might be a Wikipedia page (unfortunately), then something from a college math department, maybe there's a ProofWiki result, and then at least one question here on math.SE. $\endgroup$
    – user153918
    May 4, 2015 at 18:03

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