为什么用方程式标记这些节点不起作用？

Question

\begin{tikzpicture}
\node[state] (x11) {$X_1^1$};
\node[state, right of=x11] (x12) {$X^2_1$};
\node[state, right of=x12] (x13) {$X^3_1$};
\node[state, right of=x13] (x14) {$X^4_1$};
\node[state, right of=x14] (x15) {$X^5_1$};

\node[state, below of=x11,label=left:$s\leq 3$] (x21) {$X^1_2$};
\node[state, below of=x12] (x22) {$X^2_2$};
\node[state, below of=x13] (x23) {$X^3_2$};
\node[state, below of=x14] (x24) {$X^4_2$};
\node[state, below of=x15] (x25) {$X^5_2$};

\node[state, below of=x21] (x31) {$X^1_3$};
\node[state, below of=x22] (x32) {$X^2_3$};
\node[state, below of=x23] (x33) {$X^3_3$};
\node[state, below of=x24] (x34) {$X^4_3$};
\node[state, below of=x25] (x35) {$X^5_3$};

\draw

(x11) edge[above] node{} (x21)
(x11) edge[above] node{} (x22)
(x13) edge[above] node{} (x24)
(x13) edge[above] node{} (x25)
(x15) edge[above] node{} (x23)
(x22) edge[above] node{} (x33)
(x22) edge[above] node{} (x31)
(x23) edge[above] node{} (x32)
(x25) edge[above] node{} (x34)
(x25) edge[above] node{} (x35)
;


\end{tikzpicture}

如果我改成，怎么label=left:$s\leq 3$就不label=left:$s=3$能再编译代码了......

我明白了! Extra }, or forgotten $。

Answer 1

@ferahfeza 评论给出了您的问题的解决方案。注意，符号=用于定位节点标签。如果有两个，解析器就会丢失。因此，=方程中的必须“隐藏”，即必须用花括号括起来。好的做法是将完整的方程括在花括号中，因为这样方程中的间距就会保留。

tikz因此，我建议使用库进行一些题外的改进chains，positioning并且quotes：

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{automata,
                chains,
                positioning,
                quotes}

\begin{document}
    \begin{tikzpicture}[
      node distance = 4mm and 4mm,
        start chain = going right,
state/.append style = {inner sep=0pt, on chain}
                    ]
\node[state] (x11) {$X_1^1$};
\node[state] (x12) {$X^2_1$};
\node[state] (x13) {$X^3_1$};
\node[state] (x14) {$X^4_1$};
\node[state] (x15) {$X^5_1$};
%
\node[state, below= of x11,
      label=left:{$s=3$}]    % <---
             (x21) {$X^1_2$};
\node[state] (x22) {$X^2_2$};
\node[state] (x23) {$X^3_2$};
\node[state] (x24) {$X^4_2$};
\node[state] (x25) {$X^5_2$};
%
\node[state, below= of x21] (x31) {$X^1_3$};
\node[state] (x32) {$X^2_3$};
\node[state] (x33) {$X^3_3$};
\node[state] (x34) {$X^4_3$};
\node[state] (x35) {$X^5_3$};

\draw   (x11) edge ["?"]    (x21)
        (x11) edge          (x22)
        (x13) edge          (x24)
        (x13) edge          (x25)
        (x15) edge          (x23)
        (x22) edge          (x33)
        (x22) edge          (x31)
        (x23) edge          (x32)
        (x25) edge          (x34)
        (x25) edge          (x35)
        ;
    \end{tikzpicture}
\end{document}