答案1
一种可能的解决方案是使用tikz-cd
。
\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\usepackage{tikz-cd}
\newcommand*\circlett[1]{%
\begin{tikzpicture}
\node[draw,circle,inner sep=.5pt] {#1};
\end{tikzpicture}}
\begin{document}
\begin{tikzcd}[row sep=4cm, column sep=2cm]
& \circlett{A} \arrow[ld,Leftrightarrow, "\mathrm{A-B}", "\mathrm{B-A}"'] & \\
\circlett{B}\arrow[rr,leftrightarrow, "\mathrm{B-C}", "\mathrm{C-B}"'] & & \circlett{C} \arrow[lu,Leftrightarrow, "\mathrm{C-A}", "\mathrm{A-C}"']
\end{tikzcd}
\end{document}