The following is my expression:
\begin{equation}
\left[
\begin{tabular}{c|c}
$y$ & $a_{bc}$ \\
\hline
$a_{ab}^T$ & $y$
\end{tabular}
\right].
\end{equation}
Note that the part a_{ab}^T is very close to the hline. I would like to have a bit larger spacing, such that 'T' from the above example is clearly separated from the hline. I've tried using [pt], but it did not work. I'm using
\documentclass[a4paper,12pt]{book}
