I posted a question not long ago. A similar question was posted years ago, with an accepted answer (Edit: now deleted) and a second answer. But the accepted answer was wrong, although it received favorable commentary from a high-reputation user (who had, in fact, posted an answer I believe to be correct).

The error, obviously, is subtle -- it took me some time to see the problem. What protocol, if any, exists to warn future users who, seeing the duplicate, might not even post a question but simply rely on the accepted but wrong answer?

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    $\begingroup$ I guess commenting on the accepted answer is the only thing that you can do at present... Flagging the answer for moderator intervention clearly doesn't work as it's not their job to check the correctness of the answer. $\endgroup$ Mar 14, 2019 at 11:07
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    $\begingroup$ Leave a comment (as YuiToCheng suggests), downvote, and / or flag it for deletion. $\endgroup$
    – Xander Henderson Mod
    Mar 14, 2019 at 15:57
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    $\begingroup$ Especially if the error is as subtle as you suggest, and if the error is avoided in another Answer, leaving a Comment on one or both of the Answers pointing out the subtlety would be a welcome contribution. You could consider, if time permits, posting your own Answer to explain the subtlety if it requires more space than a Comment would allow. $\endgroup$
    – hardmath
    Mar 14, 2019 at 16:58
  • $\begingroup$ I posted my own question pointing out the error (and asking for confirmation that it really was an error) and posted a comment in the original question summarizing the problem and pointing to my new question. I guess there's not much more to do. $\endgroup$ Mar 14, 2019 at 17:07
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    $\begingroup$ You should comment and downvote. Don't flag it for moderator attention --- we are deliberately not responsible for correctness. $\endgroup$
    – davidlowryduda Mod
    Mar 14, 2019 at 18:12
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    $\begingroup$ @RobertShore You may also comment on the question asking the OP to reconsider accepting other people's answer. $\endgroup$ Mar 15, 2019 at 8:53
  • $\begingroup$ @davidlowryduda Why don’t you post that as an answer? $\endgroup$ Mar 27, 2019 at 20:55

1 Answer 1


It happened to me too. A nice, friendly comment with a strong mathematical argument pointing to the issue, is the best you can do.

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    $\begingroup$ Sometimes people are intentionally ignoring comments on old posts... If they don't repond, you can post a new answer to the question, pointing out the error and giving a correct solution. $\endgroup$ Mar 28, 2019 at 4:54

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