\documentclass{article}\usepackage{tikz}\pagestyle{empty}

\begin{document} \begin{center} \begin{tikzpicture}[style=thick] \foreach \x in {0,1,2} \foreach \y in {0,1,2} {\draw (\y,0) -- (\x,1);} \foreach \x in {0,1,2}{ \draw (\x,0) circle (2pt); \draw (\x,1) circle (2pt);} \end{tikzpicture} \end{center}\end{document}

See also: Original Source by Rafael

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