# Cyrillic blackboard bold

Is there a way to produce blackboard bold Cyrillic letter?

(I know I can do Greek letters with mathbbol, but I need $\mathbb{Л}$.)

• sadly, i don't know of any font that contains blackboard bold cyrillic. however, if you can find a published source in russian that uses these letters, they are good candidates for addition to unicode, and i would be happy to forward a request to the unicode committee. but they do require a published reference. – barbara beeton Oct 24 '15 at 22:38

Not really pretty, but unless you find an open shape Cyrillic font, I see not much more to do.

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[russian]{babel}
\usepackage{amsmath}

\DeclareRobustCommand{\bbel}{%
\mathord{\text{%
\ooalign{%
Л\cr
\hidewidth\kern0.125em I\hidewidth\cr
}%
}%
}}

\begin{document}

$x\bbel y^{\bbel}$

\end{document}


For the particular symbol you mention you could fake it by adding a vertical rule to the symbol either to the left or right of the main vertical stem or (egreg's suggestion) print a capital I close to the symbol or double print the symbol with a small separation

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[russian]{babel}

\begin{document}

Л

$\mbox{Л\kern-0.4em\vrule height 1.55ex depth 0ex width 0.08em}$

$\mbox{Л\kern-0.05em\vrule height 1.58ex depth 0ex width 0.08em}$

$\mbox{Л\kern-.15emI}$

$\mbox{Л\kern-0.9emЛ}$

\end{document}


But really one should go back to metafont and make a proper set of symbols.

• Why not an I? There is in the repertoire. – egreg Oct 28 '16 at 12:36
• @egreg Because I didn't think of such a good suggestion - now added to the samples above. – Andrew Swann Oct 28 '16 at 12:47