4
Here's a solution without TikZ
\documentclass{article}
\usepackage{amssymb,array,arydshln}
\begin{document}
$\renewcommand{\arraystretch}{1.2}
\left(\begin{array}{@{}c;{3pt/1.5pt}c@{}}
\mathit{GL}(2,\mathbb{R}) & \begin{array}{@{}c@{}}*\\{}*\end{array}\\
\hdashline[3pt/1.5pt]
\begin{a...