# Cases with brackets instead of curly brackets

How could I use cases with [] (both sides) instead of curly bracket as the attached picture shows?

Thank you.

• Please provide a bit more context, e.g. a minimal working example. Without anything, I can only guess that Bmatrix could help. cases is intentionally one-sided. Oct 7 '15 at 15:15
• @Chris Sorry for the lack of context. I wrote "cases" because I know it's one-sided. Thanks anyway. Oct 7 '15 at 21:48

\documentclass{article}
a= \left[\begin{aligned} &2 \rightarrow \text{John}\\ &5 \rightarrow \text{Mary}\\ &7 \rightarrow \text{Ann} \end{aligned}\right]
$a= \begin{bmatrix} 2 &\rightarrow &\text{John}\\ 5 &\rightarrow &\text{Mary}\\ 7 &\rightarrow &\text{Ann} \end{bmatrix}$
$a= \left[\begin{array}{@{}l@{\,}l@{\,}c@{}} 2 &\rightarrow &\text{John}\\ 5 &\rightarrow &\text{Mary}\\ 7 &\rightarrow &\text{Ann} \end{array}\right]$