Many times when I ask a question I found that it blocked as it is duplicate. But I don't know which question is ask before. So how can I understand that the question is duplicate or not?? Please help me

  • 7
    $\begingroup$ Usually one searches the site (either using the big search box at the top of the page, or using Google with the additional filter site:math.stackexchange.com) to check if something has not been posted before. That being said, it's still possible to miss a dupe, so please don't take dupe marks too hard. $\endgroup$ Commented Oct 16, 2017 at 3:20
  • 5
    $\begingroup$ It is rather unclear what your question is. You have marked this as (feature-request), but you do not say what is actually the feature you are requesting. $\endgroup$ Commented Oct 16, 2017 at 3:57
  • 3
    $\begingroup$ In case it is helpful, I have collected links to some search-related posts. Some useful post have been posted since that, like “Maybe answered questions” box on “Ask Question” page is much more useful than “Search Q&A” or Announcing a third-party search engine for Math StackExchange.. And you can find a few more in (search) tag on meta. (You can try frequent tab.) $\endgroup$ Commented Oct 16, 2017 at 3:59
  • 2
    $\begingroup$ I will also add link to my own answer where I tried to include specific examples how to search for some stuff: How to search math terms/notations accurately and efficiently? Could some experienced users summarize some tips here? There is also a chatroom dedicated to searching - you can also ask there. (Although I will admitted that not many users visit that room.) $\endgroup$ Commented Oct 16, 2017 at 4:02
  • 2
    $\begingroup$ The simplest thing you can do is search on google first. If you do this whenever you ask a question, that should avoid most of the duplicate votes. Even when your questions got closed as duplicate occasionally, that's not a big problem. After all, some users are very familiar with the subject and the site, that they might have different (personal) ways to locate duplicates (for example, I stored some standard questions in real analysis in my profile so that I can provide it when needed to). $\endgroup$
    – user99914
    Commented Oct 16, 2017 at 5:15
  • 4
    $\begingroup$ In case the link isn't noticed in Martin Sleziak's comments, Approach0 is awesome. Just saying. $\endgroup$ Commented Oct 16, 2017 at 14:14
  • 1
    $\begingroup$ May I also suggest changing the title? As is, the title is a bit disconnected from the post. $\endgroup$ Commented Oct 16, 2017 at 19:49
  • $\begingroup$ Check on Google if there are sites answering your question. $\endgroup$ Commented Oct 17, 2017 at 15:10

1 Answer 1


Because searching for fomulas with symbols in them is hard*, even if you try to find duplicates you may fail. Then go ahead and post. If it is closed as a duplicate, you lose no points, and the linked question gives you your answer.

If you are asking to find the answer (as you should) and not merely to gain reputation, this is exactly what you want.

*The AI in the search engines do not yet know that $xy=yx$ matches $ab=ba$. Even less do they know that both of those match "commutative law".

  • 2
    $\begingroup$ Corresponding advice to other users: if a question is a duplicate, vote to close as a duplicate; resist the temptation to downvote the question. $\endgroup$
    – GEdgar
    Commented Oct 16, 2017 at 13:55
  • 1
    $\begingroup$ Correction. You probably meant "Don't downvote because it is a duplicate." By all means downvote if it should be downvoted, regardless of whether or not it is a dupe. $\endgroup$ Commented Oct 16, 2017 at 19:50
  • 1
    $\begingroup$ If you have lots of questions closed-as-duplicate, could this trigger a question ban? $\endgroup$ Commented Oct 16, 2017 at 23:12
  • 3
    $\begingroup$ @GerryMyerson Yes, they do contribute to question ban, but much less than downvotes question. More on this: Will asking too many duplicate questions lead to a question ban? and Does marking an earlier question as a duplicate of a newer one harm the asker?. A quote from Shog9's answer: "Closing is a fairly weak signal when it comes to q-banning; voting is king. An old, closed, but well-received question is probably a net positive; a new, open, but heavily-downvoted question is gonna hurt." $\endgroup$ Commented Oct 17, 2017 at 2:54
  • $\begingroup$ "If a question is a duplicate, vote to close as a duplicate; resist the temptation to downvote the question." I never downvote strictly for the fact that a question may have been asked before. But if the duplicate question is posted in the form of an imperative, and essentially reads like a copy and paste from a text, I feel obliged to downvote, whether or not it happens to be a dupe. So, I'm saying that dupe or not, if it's a poor question, I'll downvote, and if it's a very, very, poor question, dupe or not, I'll vote to close it too, for the appropriate reason (off topic, unclear, etc). $\endgroup$
    – amWhy
    Commented Oct 18, 2017 at 23:05

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .