答案1
我猜那是\Circle
来自wasysym
。
\documentclass{article}
\usepackage{amsmath,amssymb}
\DeclareSymbolFont{wasysym}{U}{wasy}{m}{n}
\DeclareMathSymbol{\Circle}{\mathord}{wasysym}{35}
\makeatletter
\newcommand{\BlackSquare}{{\mathpalette\adapt@to@Circle\blacksquare}}
\newcommand{\adapt@to@Circle}[2]{%
\sbox\z@{$#1\Circle$}%
\sbox\tw@{$#1#2$}%
\raisebox{-0.5\dimexpr\ht\tw@-\ht\z@+\dp\z@}{$\m@th#1#2$}%
}
\makeatother
\begin{document}
$P\{X,Y \mid \Circle,\BlackSquare\}$
\setlength{\fboxsep}{0pt}\setlength{\fboxrule}{0.1pt}% for the demonstration
\fbox{$\Circle\BlackSquare$}
\fbox{$\scriptstyle\Circle\BlackSquare$}
\fbox{$\scriptscriptstyle\Circle\BlackSquare$}
\end{document}
请注意,符号wasysym
在下标和上标中不会缩放,因此我选择\Circle
以不同的方式实现。