Skipping over minor details, this may be accomplished with a `tabular`

:

```
\usepackage{array}
\newcolumntype{C}{>{$\displaystyle}c<{$}}
\newcommand{\onecol}[1]{\multicolumn{2}{C}{#1}}
```

The above code should go in the preamble. Then the big thing can be set by

```
\begin{figure}
\centering
\renewcommand{\arraystretch}{2} % adjust here for interrow spacing
\begin{tabular}{CC}
\onecol{Formula for first line} \\
\onecol{Formula for second line} \\
\onecol{Formula for third line} \\
Left formula & right formula (row 4)\\
Left formula & right formula (row 5)\\
...
\end{tabular}
\caption{Sequent calculus formulation}\label{fig:seqcalc}
\end{figure}
```

Instead of setting `\arraystretch`

you can define

```
\newcommand\mystrut{\vrule width 0pt height 24pt depth 24pt}
```

and insert `\mystrut`

in a cell in each row but the first and the last. Adjust the dimensions to suit.

Recently I have finished my thesis, and I added an appendix with some CINT (C/C++) code. I used `listings`

package, adding those lines on my preamble:

```
\definecolor{listinggray}{gray}{0.9}
\definecolor{lbcolor}{rgb}{0.9,0.9,0.9}
\lstset{
backgroundcolor=\color{lbcolor},
tabsize=4,
% rulecolor=,
language=[GNU]C++,
basicstyle=\scriptsize,
upquote=true,
aboveskip={1.5\baselineskip},
columns=fixed,
showstringspaces=false,
extendedchars=false,
breaklines=true,
prebreak = \raisebox{0ex}[0ex][0ex]{\ensuremath{\hookleftarrow}},
frame=single,
numbers=left,
showtabs=false,
showspaces=false,
showstringspaces=false,
identifierstyle=\ttfamily,
keywordstyle=\color[rgb]{0,0,1},
commentstyle=\color[rgb]{0.026,0.112,0.095},
stringstyle=\color[rgb]{0.627,0.126,0.941},
numberstyle=\color[rgb]{0.205, 0.142, 0.73},
% \lstdefinestyle{C++}{language=C++,style=numbers}’.
}
\lstset{
backgroundcolor=\color{lbcolor},
tabsize=4,
language=C++,
captionpos=b,
tabsize=3,
frame=lines,
numbers=left,
numberstyle=\tiny,
numbersep=5pt,
breaklines=true,
showstringspaces=false,
basicstyle=\footnotesize,
% identifierstyle=\color{magenta},
keywordstyle=\color[rgb]{0,0,1},
commentstyle=\color{Darkgreen},
stringstyle=\color{red}
}
```

The output I get looks like that:

## Best Answer

Peter Smith's very useful LaTeX for Logicians page offers suggestions both for downward branching proof-trees and for natural deduction proofs in both Gentzen sequent-style (the tree-like style you seem to be after) and Fitch-style.

I've not used any of the alternatives for proof trees, as I use Fitch-style natural deduction proofs. But, I've found Smith a most reliable guide and for your desire he recommends as best of breed Sam Buss's

`bussproofs.sty`

. Smith also has remarks about a few other alternatives that you might want to check out.A quick example to produce your example tree would be: