# Default spaces between letters in math-mode

Question for TeX-gurus. Sometimes I find that the default spaces between letters in the math TeX-mode is to short. Say, I would prefer to have slightly increased spaces between abc in $abc$. On the other hand, one to type something like $a\,b\,c$ is not convenient and the default space \, is too large here. Whether exists any way for an automatic tune of such a kind kerning. I think that this may be related to a low level TeX-format file. However, does solution exists? I can, of course, redefine the \thinspace-command \, but, again, the constant usage of \, is rather awkward.

• There is no default spacing, because there's no spacing to begin with. Letters in the math italic font have side bearings that should make them well spaced when simply put next to each other. Oct 30, 2014 at 15:19
• Some info on math spacing: How does math mode work?. Oct 30, 2014 at 15:22

There is no space so you will have to modify the font you are using or switch to some font that suits you better. Each font has some kerning definitions and sometimes even special kernings for certain character pairs. This is a lot of work to create such a font or to modify. So I think, you are better with searching for some wider spaced font for maths.

If you want to insert the bigger space just for certain pairings, you will have to do this manually for each appearance or you define commands for often used combinations. In my MWE, I just show these possibilities. The yellow blocks show the different kernings.

% arara: lualatex

\documentclass{article}
\usepackage{lua-visual-debug}
\newcommand*{\myABC}{\ensuremath{a\mkern1.5mu b\mkern1.5mu c}}

\begin{document}
$abc$

$a\,b\,c$

$a\mkern.8mu b\mkern.8mu c$

\myABC{} or $\myABC$
\end{document}


If you decide to add a kern to the parts which disturb you, you might want to define a macro for this: \newcommand*{\mk}{\mkern.8mu}. Use this as $a\mk b\mk c$! Like this, you can modify your spacing globally in your preamble or completely get rid of it.