# Is there an option to refer to things previously said anywhere in stackexchange?

I think it would be a good idea if you could point to things by referring them by an special symbol instead of writing it out or copying it. But I'm not sure whether or not there is an option like that.

 I added here a hyperlink to your most upvoted question. Please click the edit button under this question to see the syntax. The URL contains two mysterious numbers at the end. The first of those is the number of your question. The second number is my UserID. The latter is somewhat unnecessary, but it does serve a purpose. That purpose would be off-topic here. Regards, JL [/Edit]

What I meant is this:

statement 1:theorem.statement2:explanation of theorem.statement 3:equations of theorem.

How to refer only to the equation part? But I know it's complex since you can't assign the same tag for each statement. Instead if there was a computer generated number you can uniquely identify each statement.

• Perhaps the (hyper)linking syntax? Put the brief text description of what you want to reference in square brackets [...] immediately followed by the URL in parentheses (...). Oct 28 '14 at 12:09
• I added an example link to your question body to make sure that you see it in action. Oct 28 '14 at 12:43
• okay that's right but is there any way to avoid the site's name.But I agree with the UserID and question number that's good.now only I could get the (ambiguity) if we use just a single character for referring. Oct 28 '14 at 12:47
• @JyrkiLahtonen: I always remove my userid from the URLs. That is probably why I don't even have an announcer badge.
– robjohn Mod
Oct 28 '14 at 14:23
• Justin, I forget to explain that by clicking the "share" -button under your linked question a window pops up. I copy/pasted the above URL from that window. This feature is to make generation of those URLs easier. No need to dig up the question ID nor to remember your userID! Oct 28 '14 at 14:29
• For people not aware of this, adding your user ID at the end makes it so that the software knows you're the one who shared the link; it's used for badges such as Announcer or Publicist. It's not technically necessary (you can remove it and the link will work just fine). Oct 28 '14 at 15:12
• how can you do that? Oct 29 '14 at 10:45
• So you want to somehow change the syntax to link to questions, answers, comments, etc.? So instead of linking to the first comment like this: [the first comment](http://meta.math.stackexchange.com/questions/17173/is-there-an-option-to-refer-to-things-previously-said-anywhere-in-stackexchange#comment63502_17173) I would use syntax similar to [comment:63502_17173]. To do that I would still need the number identifying the comment... Oct 29 '14 at 10:49
• ...which I would get by clicking on the timestamp and copying it from the url. I think that it's easier to use hyperlink and copy the whole url. (Similarly for questions, answers, posts in chat...) See also How to link to a comment?, where this is explained. Oct 29 '14 at 10:50
• but how can you refer to the most important statement like it might be a theorem. Oct 29 '14 at 10:53
• As an addition to hardmath's comment, here is the part of editing help which deals with hyperlinks. (I have to admit I do not know exactly what your question is about.) Oct 29 '14 at 11:00
• I have updated the post to explain what I meant. Oct 29 '14 at 11:20
• Is this what you're looking for? Oct 29 '14 at 14:37
• ALmost this.but is this going to be a unique label.I couldn't understand what you meant by "{your tag}".If it's a user tag then it would be unique.Could you show an simple example.what you have shown in (17.Tags and References) example is hard to understand. Oct 30 '14 at 11:01
• @justin I think you are better off asking the poster of the answer I linked to. Write a comment there, and hope he or someone else will respond. You could include a link to this discussion if you want. Oct 30 '14 at 13:23

This is not an answer to the question - it is more of an attempt to show examples how hyperlinks can work. I tried to answer some requests for clarification posted by the OP in the comments. And also this post also contains some experiments with labels of equations and linking to them.

I have made the answer community wiki. Feel free to edit it and add further explanations if needed.

To see the source, click on edit on see the revision history.

As explained in editing help, you can use syntax such of the form [text](url) to create links. For example, by writing [Wikipedia](http://en.wikipedia.org/wiki/) you can link to Wikipedia.

This syntax works also in comments. When editing a post (an answer or a question), you can instead of typing this syntax click on hyperlink button or use the shortcut Ctrl+I.

This is not only for linking to post on SE network - you can link to anything what has an URL. So the only question is how to get link to a post or a comment.

• To get a link for a post, you can click on share under answer or question and copy in from there.
• To get a link to a comment, click on the timestamp. (As explained here.)

So let us try some examples:

• I can link to this question like this [like this](http://meta.math.stackexchange.com/q/17173/) or like this [like this](http://meta.math.stackexchange.com/questions/17173/is-there-an-option-to-refer-to-things-previously-said-anywhere-in-stackexchange). In the first case I obtained link by clicking on share under the question. In the second case I copied it from the browsers address bar.
• Linking to an answer is pretty much the same, for example, I can link to an answer like this or like this.
• When I click on a timestamp of some comment, I will get an url which can be used to link to the comment.
• Note that if I put link to some question in a post (like this: http://meta.math.stackexchange.com/questions/17173/) it will be rendered as the link where the text is the title of the question: http://meta.math.stackexchange.com/questions/17173/ (This does not work in comments, only in posts.)

Labeling equations and linking to them

I will basically repeat (and test) things from this answer

If I want to refer to some equation I can add a label to it using the following syntax. $$x^2+y^2=z^2 \tag{P} \label{EQpyt}$$ $$x^2+y^2=z^2 \tag{P} \label{EQpyt}$$ Now if I write $\eqref{EQpyt}$it renders as $\eqref{EQpyt}$.

Note that you may click on (P) above. You see that it brings you to this link: http://meta.math.stackexchange.com/questions/17173/is-there-an-option-to-refer-to-things-previously-said-anywhere-in-stackexchange/17192#mjx-eqn-EQpyt
You can use the same link to refer to this equation from any other site.

Let us try a different equation $$x^3+y^3=z^3 \tag{3} \label{EQ3}$$ $$x^3+y^3=z^3 \tag{3} \label{EQ3}$$ Here is reference to it: \eqref{EQ3}. Again, we get a link which can be used when referring to this equation from another post (or another website).

• can we refer only to equations like this or can we also refer to theorems? Nov 4 '14 at 6:51
• I guess you don't mean something like: We can use Stolz-Cesaro theorem, see here or This follows from Stolz-Cesaro theorem. Nov 4 '14 at 7:03
• but how did you defined "here"? Nov 4 '14 at 7:12
• The syntax I have used is: We can use Stolz-Cesaro theorem, see [here](http://math.stackexchange.com/a/100542/. and This follows from [Stolz-Cesaro theorem](http://en.wikipedia.org/wiki/Stolz-Cesaro_theorem). Nov 4 '14 at 7:14
• how to get "a" and "100542". Nov 4 '14 at 7:26
• I went to that answer and clicked on share. (This is already explained in the post.) The main question is whether this is what you wanted to achieve. (I guess not, but I asked just to be clear. I should point out that if there is a long answer, this will bring the user to the beginning of the answer. If I understood you correctly, you want some way to refer no only the answer as the whole, but also some specific part of the answer.) Nov 4 '14 at 7:31
• :my intention is really which you said in the last sentence.I think that to implement this you also need to have a user tag id because anyone could create tags of the same name p.I think the site should also restrict when a user creates the same tag two times.Is there a question tag number for stack exchange?Also if there is a user tag id for the site could you tell me how to get it? Nov 5 '14 at 6:57
• I am not sure what you mean by user tag, but every user has an identifier (which is unique per site). If you click on justin under any of your posts/comments, you get to the page http://meta.math.stackexchange.com/users/172687/justin. The number 172687 is your user id on math.SE. (You have accounts also on other sites, for example on SO. On another site you have a different user id.) Nov 5 '14 at 6:59
• okay really I meant user identifier.but is there an option to use an user-id and label to refer to a part of your answer rather than using html tags? Nov 5 '14 at 7:04