答案1
由于\bullet
可能太大胆了,可以缩放以适应:
\documentclass{article}
\usepackage{graphicx}
\newcommand\sbullet[1][.5]{\mathbin{\vcenter{\hbox{\scalebox{#1}{$\bullet$}}}}}
\begin{document}
$A
\cdot A
\sbullet A
\sbullet[.75] A
\bullet A$
\end{document}
如果在较小的数学运算中需要它,
\documentclass{article}
\usepackage{graphicx,scalerel}
\newcommand\sbullet[1][.5]{\mathbin{\ThisStyle{\vcenter{\hbox{%
\scalebox{#1}{$\SavedStyle\bullet$}}}}}%
}
\begin{document}
$A
\cdot A
\sbullet A
\sbullet[.75] A
\bullet A$
$\scriptstyle A
\cdot A
\sbullet A
\sbullet[.75] A
\bullet A$
$\scriptscriptstyle A
\cdot A
\sbullet A
\sbullet[.75] A
\bullet A$
\end{document}