\begin{tikzcd}[column sep=small]
0 \arrow[r] & A \arrow[r, "f"] \arrow[d, "\xi_n"'] & A \arrow[r] \arrow[d] & A/fA \arrow[r] \arrow[d, no head, "\|" description] & 0 \\
0 \arrow[r] & E_n \arrow[r] & E_{n+1} \arrow[r] & A/fA \arrow[r] & 0
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small]
\text{(ii)} \arrow[d, Rightarrow] \arrow[dr, Rightarrow] & &
\text{(iii bis)} \arrow[ll, Rightarrow] \arrow[d, Rightarrow] \\
\text{(i)} & \text{(iii)} \arrow[l, Rightarrow] & \text{(iii ter)}
\arrow[l, Rightarrow]
\end{tikzcd}

\begin{tikzcd}
\text{b} \arrow[r, Rightarrow] \arrow[d, Rightarrow] & \text{b}' \arrow[d, Rightarrow] \\
\text{b}(q) \arrow[r, Rightarrow] & \text{b}'(q)
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small, nodes={font=\scriptsize}]
\hat{H}(G,M) \arrow[r, "\sim"] \arrow[d, "?"'] &
\hat{H}(G_{i},M)^{G/G_{i}} \arrow[r, "\alpha"] &
\hat{H}(G_{i}, M_{\mathfrak{m}_{0}})^{G_{d}/G_{i}} \\
\hat{H}(G_{d},M)^{G/G_{d}} \arrow[r, "\beta"'] &
\hat{H}(G_{d}, M_{\mathfrak{m}_{0}}) \arrow[r, "\sim"'] &
\hat{H}(G_{d},M)_{\mathcal{O}_{d} - \mathfrak{m} \cap \mathcal{O}_{d}}
\arrow[u, "?"']
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small, nodes={font=\scriptsize}]
& \text{a} \arrow[dl, Rightarrow] \arrow[dr, Rightarrow] & \\
\text{b} \arrow[d, Rightarrow] & & \text{c} \\
\text{b}' & &
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small, nodes={font=\scriptsize}]
k' = \tilde{k}k & k \arrow[l] \\
K \arrow[u] & \tilde{k}K \arrow[l] \arrow[r, "G'"] & \tilde{K}K
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small]
x \arrow[d] & x_{\bar y} \arrow[l] \arrow[d] \\
X & X_{\bar y} \arrow[l]
\end{tikzcd}

\begin{tikzcd}[row sep=small]
E = Y[t_{1}, \ldots, t_{r}] \arrow[d] \\
Y
\end{tikzcd}

\begin{tikzcd}[column sep=small, row sep=small, nodes={font=\scriptsize}]
H^{i-1}(U,F) \arrow[r] & H^{i}_{Y}(X,F) \arrow[r] \arrow[d, no head, "\wr"] & H^{i}(X,F) \arrow[r] & H^{i}(U,F) \arrow[r] & H^{i+1}_{Y}(X,F) \arrow[d, no head, "\wr"] \\
 & H^{i-2}(Y, F_{Y} \otimes \check{T}_{\ell}) & & & H^{i-1}(Y, F_{Y} \otimes \check{T}_{\ell})
\end{tikzcd}