歌剧理论、树和身份

Question

我正在尝试实现 Wikipedia 上显示的 operad 插入这里。我无法弄清楚如何\circ 在前两个之间放置一个符号，并在其他符号之间放置一个等号，如 Wikipedia 所示。此外，我确信我拥有的东西不是我正在寻找的树结构，但到目前为止，我拥有的最好的包是这个。有人可以修改以下内容以显示所需的结果吗？

到目前为止，我写的内容如下

 \begin{left}
   \begin{frame 3, 4}
\begin{Example of a graph}
\centering
\begin{tikzpicture}
  [scale=.8,auto=left,every node/.style={circle,fill=blue!20}]
  %\node (n6) at (1,10) {6};
  \node (n4) at (3,4)  {4};
  %\node (n5) at (3,2)  {5};
  \node (n1) at (1.5,2)  {1};
  \node (n2) at (3,6)  {2};
  \node (n3) at (4.5,2)  {3};

  \foreach \from/\to [count=\xi from 2] in {n2/n4,n4/n3,n4/n1}
    \draw<\xi-> (\from) -- (\to);
%\visible<6->{\draw (n2) to [out=-20,in=35] (n3);}
%\visible<7->{\draw (n2) to [out=200,in=135] (n1);}
%\draw<8-> (n2) to [out=-20,in=35] (n5);
\end{tikzpicture}
\caption{A}
%\end{figure}
%\end{frame}
%\begin{frame 3, 4}
\begin{frame 3, 4}
\begin{Example of a graph}
\centering
\begin{tikzpicture}
  [scale=.8,auto=left,every node/.style={circle,fill=blue!20}]
  %\node (n6) at (1,10) {6};
  \node (n4) at (3,4)  {4};
  %\node (n5) at (3,2)  {5};
  \node (n1) at (1.5,2)  {1};
  \node (n2) at (3,6)  {2};
  \node (n3) at (4.5,2)  {3};

  \foreach \from/\to [count=\xi from 2] in {n2/n4,n4/n3,n4/n1}
    \draw<\xi-> (\from) -- (\to);
%\visible<6->{\draw (n2) to [out=-20,in=35] (n3);}
%\visible<7->{\draw (n2) to [out=200,in=135] (n1);}
%\draw<8-> (n2) to [out=-20,in=35] (n5);
\end{tikzpicture}
\caption{B}
%\end{figure}
%\end{frame}
%\begin{frame 3, 4}
\begin{frame 3, 4}
\begin{Example of a graph}
\centering
\begin{tikzpicture}
  [scale=.8,auto=left,every node/.style={circle,fill=blue!20}]
  \node (n6) at (4.5,8) {6};
  \node (n4) at (3,4)  {4};
  \node (n5) at (3,6)  {5};
  \node (n1) at (1.5,2)  {1};
  \node (n2) at (3,6)  {2};
  \node (n3) at (4.5,2)  {3};
  \node (n7) at (4.5,10) {7};
  \node (n9) at (6,6) {8};
  \foreach \from/\to [count=\xi from 2] in {n2/n4,n4/n3,n4/n1, n6/n2,n7/n6,n6/n9}
    \draw<\xi-> (\from) -- (\to);
%\visible<6->{\draw (n2) to [out=-20,in=35] (n3);}
%\visible<7->{\draw (n2) to [out=200,in=135] (n1);}
%\draw<8-> (n2) to [out=-20,in=35] (n5);
\end{tikzpicture}
\caption{C}
%\end{figure}
%\end{frame}
%\begin{frame 3, 4}
\begin{frame 3, 4}
\begin{Example of a graph}
\centering
\begin{tikzpicture}
  [scale=.8,auto=left,every node/.style={circle,fill=blue!20}]
  \node (n6) at (4.5,10) {6};
  \node (n4) at (3,4)  {4};
  \node (n5) at (7,2)  {5};
  \node (n1) at (1.5,2)  {1};
  \node (n2) at (4.5,6)  {2};
  \node (n3) at (4.5,2)  {3};

  \foreach \from/\to [count=\xi from 2] in {n2/n4,n4/n3,n4/n1,n2/n5, n6/n2}
    \draw<\xi-> (\from) -- (\to);
%\visible<6->{\draw (n2) to [out=-20,in=35] (n3);}
%\visible<7->{\draw (n2) to [out=200,in=135] (n1);}
%\draw<8-> (n2) to [out=-20,in=35] (n5);
\end{tikzpicture}
\caption{D}
\end{figure}
\end{frame}

\end{left}