# A letter looks like number 3. What is it?

I came across this symbol (the one looks like 3) when I read a book this afternoon. I never saw such a symbol before. Is it a Greek letter? What is its LaTeX code?

• Looks like the cyrillic zemlja (the equivalent of the Z for the Latin alphabet). – Bernard Jul 5 '17 at 23:44
• Did you try detexify ? – Paul Gaborit Jul 5 '17 at 23:44
• @PaulGaborit Yes, I did. Detexify doesn't give the right one. – jwyao Jul 5 '17 at 23:45
• Context from the rest of the book? – ShreevatsaR Jul 5 '17 at 23:45
• looks like a fraktur Z to me -- \frak{Z}. – barbara beeton Jul 6 '17 at 1:34

It is \mathfrak{Z} from the STIX font.

\documentclass{article}
\usepackage{amsmath}
\usepackage{stix}
\begin{document}

$\sqrt{n} ( \mathscr{K}_n - \mathscr{K} ) \xrightarrow{d} \mathfrak{Z}$

\end{document}

this is almost certainly a fraktur Z --$\frak{Z}$.

while the letter does look quite like the cyrillic Ze, in western math there is a very long history of using the fraktur alphabet, but the only "common" cyrillic letter i know of that has made its way into western math is the Sha (first letter of the name shafarevich, and also used for the shuffle product).

• \frak_Z+ should be \frak{Z}, I presume. – Henri Menke Jul 6 '17 at 2:40
• Also, why is there so little space between ) and \xrightarrow in my answer? – Henri Menke Jul 6 '17 at 2:42
• @HenriMenke -- thanks for noticing typo -- fixed. (could have sworn i checked that, but machines here have been behaving unpredictably for the past week.) regarding bad spacing in your answer re stix font, there are still a lot of niceties that have to be sorted out there. i'll put that on our list. – barbara beeton Jul 6 '17 at 12:13
• @HenriMenke -- on testing your example here, the bad positioning of the arrow is confirmed, but only with stix 1; stix 2 isn't yet fully available, but i will test this when it is. (so i have a different question -- how did whoever created the example shown in the original question get it right?) – barbara beeton Jul 6 '17 at 12:43
• @StevenB.Segletes -- no need to sleuth, actually. i learned to read fraktur in my childhood. didn't learn to read cyrillic until i was in college. so for me, this was a no-brainer. – barbara beeton Jul 6 '17 at 13:30