Tikz 绘图的内容太复杂了，目前没有精力去仔细学习，只是简单记录一些可能用到的例子。

tikz-cd

交换图

绘制简易交换图也是一个常见的需求，可以使用 tikz-cd 宏包实现。

例如 

1
2
3
4
5
6
7
8
9
10
\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}

简易概念图

可以用 tikz-cd 绘制一些概念图。

例如

对应源码 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
\documentclass[tikz,border=10pt]{standalone}
\usepackage{tikz-cd}
\usepackage{amsmath}

\begin{document}

\begin{tikzcd}[row sep=huge, column sep=huge,
        every label/.append style={font=\normalsize}]
    X_{11} \arrow[d, dashed] \arrow[rr,"{\textsf{ABC}}"]                          &  & X_{21}  \arrow[d, dashed]   \\
    X_{21} \arrow[d,"{\textsf{UVW}}", dashed] \arrow[rr, "{\textsf{DEF}}"]                          &  & X_{22}\arrow[d, dashed]     \\
    X_{31}  \arrow[rr, "{\textsf{XYZ}}", red] &  & X_{32}
\end{tikzcd}

\end{document}

例如

对应源码 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
\documentclass[tikz,border=10pt]{standalone}
\usepackage{tikz-cd}
\usepackage{amsmath}

\begin{document}

\begin{tikzcd}[row sep=huge, column sep=huge,
        every label/.append style={font=\normalsize}]
    \mathcal{P}{}_h^\varepsilon \arrow[dd,"{\textsf{$h \to 0$}}" swap, dashed] \arrow[rr, "{\textsf{$\varepsilon \to 0$}}"]  &  &  \mathcal{P}{}_h^0 \arrow[dd,"{\textsf{$h \to 0$}}", dashed]
    \\
    \\
   \mathcal{P}{}^\varepsilon   \arrow[rr, "{\textsf{$\varepsilon \to 0$}}" swap] &  & \mathcal{P}{}^0
\end{tikzcd}

\end{document}