\usetikzlibrary{arrows}
\usetikzlibrary{shapes}
\usetikzlibrary{decorations.pathreplacing}

\begin{tikzpicture}[node distance=2cm, auto]
  \node (P) {$X^{(p)}$};
  \node (B) [right of=P] {$X$};
  \node (A) [below of=P] {$S$};
  \node (C) [below of=B] {$S$};
  \node (P1) [node distance=1.4cm, left of=P, above of=P] {$X$};
  \node (spacing) [node distance=1.9cm, above of=P] {\,};
  \draw[->] (P) to node {\scriptsize $\left(F_S\right)_X$} (B);
  \draw[->] (P) to node [swap] {$$} (A);
  \draw[->] (A) to node [swap] {\scriptsize $F_S$} (C);
  \draw[->] (B) to node {\scriptsize $\varphi$} (C);
  \draw[->, bend right] (P1) to node [swap] {\scriptsize $\varphi$} (A);
  \draw[->, bend left] (P1) to node [pos=0.7] {\scriptsize $F_X$} (B);
  \draw[->] (P1) to node {\scriptsize $F_{X/S}$} (P);
\end{tikzpicture}

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• to remix – to adapt the work

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https://creativecommons.org/licenses/by-sa/4.0CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 truetrue