# Grouping lines in cases and aligning them

I am reading an article, where I faced the following:

I want to write such a thing in LaTeX. Basically, this whole thing is in a bracket, every two lines are grouped and labeled together, and there is also an alignment of three columns within the bracket.

• Could you please kindly provide us with what you have tried such that we do not have to type the formulae from the screen shot? – marmot Mar 20 at 3:57

It is possible e.g. with empheq, align and aligned.

\documentclass[fleqn]{article}
\usepackage{amsmath,empheq}
\begin{document}
\begin{subequations}
\begin{empheq}[left={\empheqlbrace}]{align}
\begin{aligned}
d^\mathsf{T}u+\left(1+d^\mathsf{T}r\right)f(\dots) &\le 0 \\
1+d^\mathsf{T}r &\ge 0
\end{aligned} &\\
\begin{aligned}
-D_i^\mathsf{T}u+\left(-D_i^\mathsf{T}\right)f(\dots) &\le 0 \\
-D_i^\mathsf{T} &\ge 0