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In the answers to package for \mathbb{lowercase letter} symbol there are two options for a blackboard bold font that includes lower case letters. They look like this:

enter image description here

Unfortunately neither of these look very good to me. The mathbol one is better, but still looks pretty awkward, with the n being much wider than the s, for example.

On the other hand, MathJax has quite a nice font for this - if I write the same thing on a Stack Exchange site that supports it, I get this:

enter image description here

I know that MathJax isn't LaTeX, but since the font exists I'm wondering if there is a LaTeX package that provides it, or something similar. I wouldn't use the mathbol or bbm fonts in a paper, but I would use this if there was a way to generate it in LaTeX.

Here's the mwe for the two LaTeX packages:

\documentclass{article}
\usepackage{mathbbol}
\usepackage{bbm}
\begin{document}

mathbol package: $\mathbb{Lens}$


bbm package: $\mathbbm{Lens}$


\end{document}
N. Virgo
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  • Is it an option to use LuaTeX and to load one of the many OpenType fonts that have these lower case double struck letters? – mickep Mar 31 '23 at 10:46
  • @mickep unfortunately I'd run into the age-old issue that arXiv doesn't support LuaTeX. I really wish they did. – N. Virgo Mar 31 '23 at 10:48

1 Answers1

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The only font I know which isn't really ugly is STIX2-bb.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}

\DeclareFontFamily{U}{stix2bb}{\skewchar\font127 }
\DeclareFontShape{U}{stix2bb}{m}{n} {<-> stix2-mathbb}{}
\DeclareMathAlphabet{\mathbb}{U}{stix2bb}{m}{n}


\begin{document}


$X+\mathbb{X}$


$\mathbb{AbcdeFghi}$


\end{document}

Don't try anything else than letters inside \mathbb.

enter image description here

egreg
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  • Cool, I'm pretty sure that's exactly the font MathJax uses. – N. Virgo Mar 31 '23 at 11:43
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    @N.Virgo -- The blackboard bold in STIX2 was modeled after the old metal Monotype alphabet. Not everybody really likes it, but it's definitely "traditional". (Just a historical aside.) – barbara beeton Mar 31 '23 at 19:00