TikZ-CD demo

- Commutative diagrams with TIKZ, package documentation.

The arrow target can be specified by a direction parameter, which consists of a string of characters r, l, d, u (standing for right, left, down and up). Labels can be placed on an arrow with the quotes syntax, described in detail in the pgf manual [3, §17.10.4]. Notice the use of “\phi” in the example below.

```
\begin{tikzcd}
A \arrow[rd] \arrow[r, "\phi"] & B \\
& C
\end{tikzcd}
```

```
\begin{tikzcd}
A \arrow[r, "\phi"] \arrow[d, red]
& B \arrow[d, "\psi" red] \\
C \arrow[r, red, "\eta" blue]
& D
\end{tikzcd}
```

```
\begin{tikzcd}
A \arrow[r, "\phi" near start, "\psi"', "\eta" near end] & B
\end{tikzcd}
```

```
\begin{tikzcd}
T
\arrow[drr, bend left, "x"]
\arrow[ddr, bend right, "y"]
\arrow[dr, dotted, "{(x,y)}" description] & & \\
& X \times_Z Y \arrow[r, "p"] \arrow[d, "q"]
& X \arrow[d, "f"] \\
& Y \arrow[r, "g"]
& Z
\end{tikzcd}
```

```
\begin{tikzcd}[column sep=tiny]
& \pi_1(U_1) \ar[dr] \ar[drr, "j_1", bend left=20]
&
&[1.5em] \\
\pi_1(U_1\cap U_2) \ar[ur, "i_1"] \ar[dr, "i_2"']
&
& \pi_1(U_1) \ast_{ \pi_1(U_1\cap U_2)} \pi_1(U_2) \ar[r, dashed, "\simeq"]
& \pi_1(X) \\
& \pi_1(U_2) \ar[ur]\ar[urr, "j_2"', bend right=20]
&
&
\end{tikzcd}
```

category: demo