\documentclass{standalone} \usepackage{tikz} \usetikzlibrary{arrows} \begin{document} \begin{tikzpicture} \node (a) at (-2,2) {$\Delta^{\{n-1,n\}}$}; \node (b) at (0,2) {$\Lambda^n_n$}; \node (c) at (2,2) {$C$}; \node (d) at (0,0) {$\Delta^{n}$}; \node (e) at (2,0) {$D$}; \draw[->] (a) to [out=30,in=150] (c);\draw (0,2.75) node[fill=white]{f}; \draw[->] (a) to (b); \draw[->] (b) to (c); \draw[->] (d) to (e); \draw[->] (b) to (d); \draw[->] (c) -- node[auto=left] {$p$} (e); \draw[->,dashed] (d) to (c); \end{tikzpicture} \end{document}