# Uncommon type of logical tree

I'm trying to reproduce such tree:

I know that it was created with Latex, but since I'm a beginner, I really don't know where to start. Would it be possible to create something like that in TkiZ?

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• What type of tree is that? (I've not seen one like that before.) – cfr Feb 19 '14 at 1:49
• Unfortunately, I don't know its name. It is mainly used for checking if formula is tautology. – solusipse Feb 19 '14 at 2:54
• Oh, I see how it works. Weird. (That is, different and so looks-weird-to-me.) – cfr Feb 19 '14 at 3:33

One can produce this kind of diagram using TikZ; below, an option using a matrix of math nodes:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{matrix}

\newcommand\mynot{\mathord{\sim}}

\begin{document}

\begin{tikzpicture}
\matrix[
matrix of math nodes,
row sep=-\pgflinewidth,
column sep=-\pgflinewidth,
nodes={
text width=5em,
inner xsep=7pt,
text depth=0.75ex,
text height=2ex
},
nodes in empty cells,
column 1/.style={align=left},
column 2/.style={align=right},
column 3/.style={align=left},
column 4/.style={align=right},
] (mat)
{
& 1 & 0 & \\
& \alpha\to\beta & & \\
& \mynot\beta\to\mynot\gamma & & \\
& \gamma & & \\
& & \alpha & \\
& |[align=left]|\mynot\beta & |[align=right]|\mynot\gamma & C1 \\
& \text{NO} & & N1  \\
\alpha & \beta & & C1 \\
};

\node[label={right:$\gamma$},anchor=south,yshift=3pt] at (mat-7-3.south east) {};
\node[label={below:$X$},anchor=north,yshift=8pt] at (mat-7-3.south east) {};
\node[label={left:$\beta$},anchor=south,yshift=3pt] at (mat-7-1.south east) {};

% tiny lines at the bottom
\foreach \Colu in {1,3}
{
\draw
([xshift=-4pt]mat-8-\Colu.south west) --
([xshift=4pt]mat-8-\Colu.south west)
;
\draw
([xshift=-4pt,yshift=-2pt]mat-8-\Colu.south west) --
([xshift=4pt,yshift=-2pt]mat-8-\Colu.south west)
;
}

% thick lines inside the matrix
\begin{scope}[ultra thick]
\draw
(mat-2-2.north west) --
(mat-2-3.north east)
;
\draw
(mat-1-2.north east) --
(mat-6-2.north east) --
(mat-6-1.north east) --
(mat-7-1.south east) --
(mat-7-1.south west) --
(mat-8-1.south west)
;
\draw
(mat-7-1.south east) --
(mat-7-3.south west) --
(mat-8-3.south west)
;
\draw
(mat-6-2.north east) --
(mat-6-3.north east) --
(mat-7-3.south east)
;
\end{scope}
\end{tikzpicture}

\end{document}