How to reduce spacing?

How to reduce spacing in equations?

• I want to typeset short equations (variable = value) saving space. Is there a global parameter which allows to reduce the space between operators and operands in math mode? I found out, that there is a negative space \!which could be used, but I would have to type it in each single equation, which is inefficient. \documentclass[11pt, a4paper]{scrbook} \usepackage[ngerman]{babel} \begin{document} $a_0\!\!=\!\!12{,}459$ \end{document}

• Answer:

  $a_0{=}12{,}459$ \thickmuskip=0.5\thickmuskip $a_0=12{,}459$ \thickmuskip=0mu $a_0=12{,}459$ from Typographer's view: it is not a good idea ...