[Tex/LaTex] What kind of symbol is that

symbols

enter image description here

I could not find the yellow marked symbols with Detexify, nor in the Comprehensive LaTeX symbols list. Are these symbols even supported by latex?

Best Answer

The footnote, which you haven't fully reproduced in the screenshot, provides the necessary explanation:

"Wir verwenden deutsche Buchstaben ..."

which may be translated as "we use German (i.e., Fraktur) letters..."

The two letters you've highlighted in yellow, by the way, are x and y (in Fraktur, of course).

Just as there are many (upright) Roman and Italic font faces, there are many Fraktur font faces. If you're interested in getting a reasonably faithful copy of the letters shown in the screenshot, you could do so by loading the yfonts package and using its command \textfrak to typeset the letters. (In the example below, I also make an attempt to mimic the "upright" shapes of the characters phi and psi.)

enter image description here

\documentclass{article}
\usepackage{yfonts,upgreek}  % 'upgreek' provides "upright" forms of \varphi and \psi
\begin{document}
$\upvarphi(\textfrak{x})=\uppsi(\textfrak{y})$
\end{document}

For what it's worth, I think that some of the letters produced by the \mathfrak macro of the eufrak package -- and the letter x in particular -- tend to look more "gothic" than "pure fraktur" to me.

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