Hi Jhevon,
one possible way could be using TikZ. Here's a compilable example:
Code:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}[every node/.style={anchor=west}]
\matrix (m) [matrix of math nodes,
nodes in empty cells]{
\quad & 1.\quad (x)(Q\supset Fx) & \\
& 2.\quad Q\supset Fx & \textrm{I,\textbf{UI}} & \\
& 3.\quad Q \\
& 4.\quad Fx & 2, 3, \textrm{ M.P.}\\
& 5.\quad (x)Fx & 4, \textrm{ \textbf{UG}} \\
& 6.\quad Q\supset(x)Fx & 3-5, \textrm{ C.P.} \\
& 7.\quad \parbox[t]{2.9cm}{%
$(x)(Q\supset(x)Fx)\supset$\\
$[Q\supset(x)Fx]$} & 1-6, \textrm{ C.P.}\\};
\draw[-stealth] (m-7-2.north east)
-| (m-1-1.west) |- (m-1-2);
\draw[-stealth] (m-6-2.north east)
-| (m-3-1.east) |- (m-3-2);
\end{tikzpicture}
\end{document}
The output with some comments can be found
here.
Stefan
--
TeXblog.net
