\documentclass{amsart}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[baseline=(current bounding box.east),xscale=0.4,yscale=-0.3]
\node (A0_2) at (2, 0) {$E$};
\node (A3_2) at (2, 3) {$B$};
\node (A4_0) at (0, 4) {$E'$};
\node (A6_2) at (2, 6) {$F$};
\path (A6_2) edge [-]node [auto] {$\scriptstyle{}$} (A4_0);
\path (A3_2) edge [-]node [auto] {$\scriptstyle{}$} (A0_2);
\path (A4_0) edge [-]node [auto] {$\scriptstyle{}$} (A0_2);
\path (A6_2) edge [-]node [auto] {$\scriptstyle{}$} (A3_2);