答案1
和tikz-cd
:
\documentclass{article}
\usepackage{tikz-cd}
\newcommand{\id}{\mathrm{id}}
\begin{document}
\[
\begin{tikzcd}[row sep=3.6em,column sep=1em]
& H\otimes H \arrow[rr,"S\otimes\id"] && H\otimes H \arrow[dr,"\nabla"] \\
H \arrow[ur,"\Delta"] \arrow[rr,"\varepsilon"] \arrow[dr,"\Delta"'] && K \arrow[rr,"\eta"] && H \\
& H\otimes H \arrow[rr,"\id\otimes S"'] && H\otimes H \arrow[ur,"\nabla"']
\end{tikzcd}
\]
\end{document}