There is a shorthand way of writing letters in blackboard bold: instead of using \mathbb, we use \Bbb. This substantially sped up my time writing questions and answers on math.SE. In the course of composing a question about rings, I started to wonder:

Is there a shorcut way of typesetting Fraktur letters (e.g. $\mathfrak{a}, \mathfrak{p}$) that is to \mathfrak what \Bbb is to \mathbb?

I haven't seen one used on the site, but if it exists, it would again speed up my time writing questions & answers. Anyone got an idea?

(Note: I understand that one can define personalized commands at the start of answers, but I'm talking about something that I can use without defining a shortcut, like \Bbb.)

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    $\begingroup$ \frak is similar to \sf or \rm or \bf, and all of those are different from \Bbb. $\endgroup$ – Asaf Karagila Mod Aug 21 '20 at 6:43
  • $\begingroup$ @AsafKaragila When I use \frak it seems to make everything else in the dollar signs fraktur, even when I only want to apply it to a specific letter. $\endgroup$ – Rivers McForge Aug 21 '20 at 6:46
  • $\begingroup$ Add brackets ${\frak A}BC$ to get ${\frak A}BC$. $\endgroup$ – GEdgar Aug 21 '20 at 11:06
  • $\begingroup$ Since there is \mathfrak, why is there no \textfrak ? $\endgroup$ – GEdgar Aug 21 '20 at 11:41

\frak is similar to \sf or \rm or \bf (they all change the font), and all of those are different from \Bbb (which only affects the next group).

$${\frak F\in A}\quad\text{ vs. }\quad{\Bbb F\in A}$$

  • $\begingroup$ Is there a \frak-like command that will only affect the text I put in curly braces? $\endgroup$ – Rivers McForge Aug 21 '20 at 6:50
  • $\begingroup$ No. Just like there isn't one for boldface, sans serif, or even Roman. Blackboard bold is the outlier. $\endgroup$ – Asaf Karagila Mod Aug 21 '20 at 6:50
  • $\begingroup$ 😔 Less versatile than I had hoped for, but still useful. Appreciate finding out about the other three font commands as well. Thank you! $\endgroup$ – Rivers McForge Aug 21 '20 at 6:53
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    $\begingroup$ You can still scope it with {\frak ...} $\endgroup$ – Peter Krautzberger Aug 21 '20 at 7:20
  • $\begingroup$ Fancy seeing you here, @Peter, thanks for the comment. I should have mentioned that, yes. (In fact, I did in the answer itself... :-)) $\endgroup$ – Asaf Karagila Mod Aug 21 '20 at 7:21

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