\documentclass[11pt]{report}
\usepackage{arcs}
\parindent 0pt
\pagestyle{empty}
\begin{document}
$\overarc[.1]{AB}\ \overarc[.2]{AB}\ \overarc[.3]{AB}\ 
 \overarc[.4]{AB}\ \overarc[.5]{AB}\ \overarc[.6]{AB}\ 
 \overarc[.7]{AB}\ \overarc[.8]{AB}\ \overarc[.9]{AB}\ 
 \overarc{AB}$\par
\vspace{2ex}
$\overarc[.1]{ABC}\ \overarc[.2]{ABC}\ \overarc[.3]{ABC}\ 
 \overarc[.4]{ABC}\ \overarc[.5]{ABC}\ \overarc[.6]{ABC}\ 
 \overarc[.7]{ABC}\ \overarc[.8]{ABC}\ \overarc[.9]{ABC}\ 
 \overarc{ABC}$\par
\vspace{2ex}
\overarc[.1]{ABC}\ \overarc[.2]{ABC}\ \overarc[.3]{ABC}\ 
 \overarc[.4]{ABC}\ \overarc[.5]{ABC}\ \overarc[.6]{ABC}\ 
 \overarc[.7]{ABC}\ \overarc[.8]{ABC}\ \overarc[.9]{ABC}\ 
 \overarc{ABC}\par
\vspace{4ex}
$\underarc[.1]{AB}\ \underarc[.2]{AB}\ \underarc[.3]{AB}\ 
 \underarc[.4]{AB}\ \underarc[.5]{AB}\ \underarc[.6]{AB}\ 
 \underarc[.7]{AB}\ \underarc[.8]{AB}\ \underarc[.9]{AB}\ 
 \underarc{AB}$\par
\vspace{2ex}
$\underarc[.1]{ABC}\ \underarc[.2]{ABC}\ \underarc[.3]{ABC}\ 
 \underarc[.4]{ABC}\ \underarc[.5]{ABC}\ \underarc[.6]{ABC}\ 
 \underarc[.7]{ABC}\ \underarc[.8]{ABC}\ \underarc[.9]{ABC}\ 
 \underarc{ABC}$\par
\vspace{2ex}
\underarc[.1]{ABC}\ \underarc[.2]{ABC}\ \underarc[.3]{ABC}\ 
\underarc[.4]{ABC}\ \underarc[.5]{ABC}\ \underarc[.6]{ABC}\ 
\underarc[.7]{ABC}\ \underarc[.8]{ABC}\ \underarc[.9]{ABC}\ 
\underarc{ABC}\par
\vspace{4ex}
$\overarc[.1]{ab}\ \overarc[.2]{ab}\ \overarc[.3]{ab}\ 
 \overarc[.4]{ab}\ \overarc[.5]{ab}\ \overarc[.6]{ab}\ 
 \overarc[.7]{ab}\ \overarc[.8]{ab}\ \overarc[.9]{ab}\ 
 \overarc{ab}$\par
\vspace{2ex}
$\overarc[.1]{abc}\ \overarc[.2]{abc}\ \overarc[.3]{abc}\ 
 \overarc[.4]{abc}\ \overarc[.5]{abc}\ \overarc[.6]{abc}\ 
 \overarc[.7]{abc}\ \overarc[.8]{abc}\ \overarc[.9]{abc}\ 
 \overarc{abc}$\par
\vspace{2ex}
\overarc[.1]{abc}\ \overarc[.2]{abc}\ \overarc[.3]{abc}\ 
\overarc[.4]{abc}\ \overarc[.5]{abc}\ \overarc[.6]{abc}\ 
\overarc[.7]{abc}\ \overarc[.8]{abc}\ \overarc[.9]{abc}\ 
\overarc{abc}\par
\vspace{4ex}
$\underarc[.1]{ag}\ \underarc[.2]{ag}\ \underarc[.3]{ag}\ 
 \underarc[.4]{ag}\ \underarc[.5]{ag}\ \underarc[.6]{ag}\ 
 \underarc[.7]{ag}\ \underarc[.8]{ag}\ \underarc[.9]{ag}\ 
 \underarc{ag}$\par
\vspace{2ex}
$\underarc[.1]{abg}\ \underarc[.2]{abg}\ \underarc[.3]{abg}\ 
 \underarc[.4]{abg}\ \underarc[.5]{abg}\ \underarc[.6]{abg}\ 
 \underarc[.7]{abg}\ \underarc[.8]{abg}\ \underarc[.9]{abg}\ 
 \underarc{abg}$\par
\vspace{2ex}
\underarc[.1]{abg}\ \underarc[.2]{abg}\ \underarc[.3]{abg}\ 
\underarc[.4]{abg}\ \underarc[.5]{abg}\ \underarc[.6]{abg}\ 
\underarc[.7]{abg}\ \underarc[.8]{abg}\ \underarc[.9]{abg}\ 
\underarc{abg}\par
\vspace{4ex}
\overarc{a e}\ \underarc{a e}\ \overarc{$x+y$}\ 
\underarc{$x+y$}\ 
$a_{\underarc[.6]{\tiny xy}}$\
$a^{\overarc[.6]{\tiny xy}}$
\end{document}
