# Tag Info

15

Use \mathcal I_1 to get $\mathcal I_1$.

11

Just added today... the "follow" feature.

8

That's right. You can't use user:JackOfAll. What happens if you change your username? Instead, you can search by a userid, which is the number you see in the search box when click on a user's profile. If you're interested in your own posts, you can use user:me instead.

7

The former is a block quote the later is a spoiler. There is also preformatted text, which might qualify. It looks like this. This is preformatted text. It is especially useful for code. You can get it by indenting the text with four spaces. A feature or issue with this is that it will not break you lines, but instead will add a slider. Like this. This ...

7

Regarding your questions: There is no dedicated feature to see how many users are online (but see Martin's comment for some ideas); it is also not exactly clear to me what it would mean. Generally, the site is more designed as an asynchronous medium, not for real-time or near real-time interaction. The follow feature is very new. As far as I know such a ...

6

Users can always mark their own question as favourite questions. It does make some sense, though, since it lets them follow through updates on the question and the answers from the relevant tab in their profile. (I agree that it feels a bit redundantly frivolous, though.)

6

Some of the omitted symbols here were thought to have already appeared earlier in Unicode. Your Wikipedia table says in a note The reserved code points (the "holes") in the alphabetic ranges up to U+1D551 duplicate characters in the Letterlike Symbols block For example U+2110 is "Script Capital I" and looks like ℐ allowing U+1D4A4 to be ignored ...

5

The number in the top bar is the total of your reputation points on the site (these are 437 at the moment). Having many points gives you additional options on the site; for example once on has 50 points one can write comments, once on has 2000 points one can edit other users posts, etc. See https://math.stackexchange.com/help/whats-reputation for an ...

5

The numbers are not inappropriate. This is a standard font. You can change the font on your side, if you want to. Of course basically everybody else will still see it differently. Some instructions are here How to change all fonts on Stack Exchange sites? You should not use MathJax here for writing these numbers either. That is inappropriate. You should ...

4

As hinted at in a comment you can write $\{f: \text{ for all } x, f < x\}$ $\{f: \text{ for all } x, f < x\}$

2

Is there a way to make the Greek letters displayed upright (non-italic)? Asked in comment. There is a way using unicode characters, for which one can search here: http://unicode-table.com/en. Normal use of phi is $\phi = ...$, which gives $\phi = ...$. Looking up phi on the above site gives a couple of results, if one uses 'Greek Capital Letter Phi' and ...

1

mathjax now supports auto numbering line, but turn off by default. Usage <script> window.MathJax = { tex: { tags: "ams" } }; </script> <script type="text/javascript" id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js" ></script> Now all ...

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