# Example: Logic diagram

Published 2011-12-31 | Author: Stefan Kottwitz

Math formulas and arrows with TikZ

In the Art of Problem Solving Forum somebody asked for help in creating a construction for proofs and demonstrations in Logic by LaTeX commands. Math expressions should be aligned, some connected by arrows going vertically and horizontally.

This example uses TikZ for arrows and its matrix library for math nodes. Some nodes are connected by -| or |- path construction operations.

Do you have a question regarding this example, TikZ or LaTeX in general? Just ask in the LaTeX Forum.
Oder frag auf Deutsch auf TeXwelt.de. En français: TeXnique.fr.

% Logic diagram
% Author: Stefan Kottwitz
\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]{
& 2.\quad Q\supset Fx & \textrm{I,\textbf{UI}} & \\
& 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.} \\
$(x)(Q\supset(x)Fx)\supset$\\
$[Q\supset(x)Fx]$} & 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} 