答案1
你可以用 Ti 画出弯曲的箭头钾Z:
\documentclass[]{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,bending}
\makeatletter
\newcommand\curvearrowed@[3]
{%
\begin{tikzpicture}
\node[inner sep=.05ex](a){\kern-.25ex#3\kern-.05ex};
\draw[arrows={-Latex[#1]},line width=#2]
(a.north west) to[bend left=45] (a.north east);
\end{tikzpicture}%
}
\newcommand\curvearrowed[1]
{%
\relax
\ifmmode
\mathchoice
{\curvearrowed@{}{.4pt}{$\displaystyle #1$}}
{\curvearrowed@{}{.4pt}{$\textstyle #1$}}
{\curvearrowed@{scale=.8}{.325pt}{$\scriptstyle #1$}}
{\curvearrowed@{scale=.7}{.25pt}{$\scriptscriptstyle #1$}}%
\else
\curvearrowed@{}{.4pt}{#1}%
\fi
}
\makeatother
\begin{document}
$\curvearrowed{AB}_{\curvearrowed{AM}_{\curvearrowed{AM}}}$
\curvearrowed{AB}
\end{document}