\documentclass{article}
\usepackage{dbnsymb}
\begin{document}
Here's a famous formula:
\[ V(\doublepoint) := V(\overcrossing) - V(\undercrossing), \]
and here's another way of writing it, with the new symbols as
superscripts:
\[ V(K^\doublepoint) := V(K^\overcrossing) - V(K^\undercrossing). \]
\end{document}
