Is it possible to make such a nice bracket like in the picture?
\documentclass{article}\usepackage{amsmath,amssymb}\newcommand{\Z}{\mathbb{Z}}\begin{document}\begin{align*}a\!\in\!\Z\mid b\!\in\!\Z &\left\{\begin{aligned}&\Leftrightarrow\left\{ \begin{aligned} \pm a &\mid \mp b\\ ac &\mid bc:\forall c\in\Z \end{aligned}\right.\\&\Rightarrow\left\{ \begin{aligned} a\mid bc:\forall c\in\Z\\ |a|\le |b|\lor b=0 \end{aligned}\right.\\&\land\left\{ \begin{matrix} a=0 &\Rightarrow& b=0\\ b\mid a &\Rightarrow& a=\pm b\\ b\mid c &\Rightarrow& a\mid c \end{matrix}\right.\end{aligned}\right.\end{align*}\end{document}