在圆圈之间画箭头

Question

我画了三个圆圈：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
    \begin{tikzpicture}

        \draw (0.0, 0.3) circle [radius=0.45] node (a) {$\alpha$};
        \draw (1.6, 0.3) circle [radius=0.45] node (b) {$\beta$};
        \draw (3.2, 0.3) circle [radius=0.45] node (c) {$\gamma$};

    \end{tikzpicture}
\end{document}

我现在想在边缘如下图所示的圆圈：

我尝试使用\draw [->] (a) -- (b);，但箭头两端都进入了圆圈内？我这里遗漏了什么？

Answer 1

这样做要容易得多，因为节点代表圆圈，而不仅仅是希腊字母

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
    \begin{tikzpicture}

      \node[minimum width=1cm,draw,circle] (a) at (0,0) {$\alpha$};
      \node[minimum width=1cm,draw,circle] (b) at ($(a)+(2,0)$) {$\beta$};
      \node[minimum width=1cm,draw,circle] (c) at ($(b)+(2,0)$) {$\gamma$};

      \draw[->] (a) -- (b);
      \draw[->] (c) -- (b);
      
    \end{tikzpicture}
\end{document}

Answer 2

与@daleif 答案类似（+1），但具有节点的相对定位和为圆圈定义的通用样式：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                positioning}

\begin{document}
    \begin{tikzpicture}[
node distance = 0mm and 9mm,
     C/.style = {circle, draw, minimum size =9mm, inner sep=0pt},
   arr/.style = {-Straight Barb, semithick} 
                        ]
\node (a) [C]               {$\alpha$};
\node (b) [C, right=of a]   {$\beta$};
\node (c) [C, right=of b]   {$\gamma$};
%
\draw[arr]  (a) -- (b);
\draw[arr]  (c) -- (b);
    \end{tikzpicture}
\end{document}

附录： 在节点半径固定的情况下，需要定义text width圆：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                positioning}

\begin{document}
    \begin{tikzpicture}[
node distance = 0mm and 9mm,
     C/.style = {circle, draw, text width=9mm, align=center, inner sep=0pt},
   arr/.style = {-Straight Barb, semithick} 
                        ]
\node (a) [C]               {$\alpha$};
\node (b) [C, right=of a]   {$\beta$};
\node (c) [C, right=of b]   {$\gamma$};
%
\draw[arr]  (a) -- (b);
\draw[arr]  (c) -- (b);
    \end{tikzpicture}
\end{document}

在您的特定情况下，结果是相同的：