如何在 Latex 中绘制以下图形

Question

我正在尝试用 LaTeX 绘制以下图表。但我没能成功。

Answer 1

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{decorations.markings}
\tikzset{->-/.style={decoration={ % https://tex.stackexchange.com/a/39282/121799
  markings,
  mark=at position #1 with {\arrow{>}}},postaction={decorate}},
  ->-/.default=0.5}
\begin{document}
\begin{tikzpicture}[bullet/.style={circle,fill,inner
sep=0.3em},>=stealth,thick]
 \draw[->-/.list={1/4,3/4}]
  (0,0) node[bullet,label=below:$P_1$] (P1){} to[bend left] (3,0)
  node[bullet,label=below:$P_2$] (P2){} to[bend left] cycle;
  \draw[->-=1/4] (P1.center) to[out=30,in=30] ++ (120:1.5)
  to[out=210,in=210] cycle;
  \draw[->-=1/4] (P2.center) to[out=150,in=150] ++ (60:1.5)
  to[out=-30,in=-30] cycle;
\end{tikzpicture}
\end{document}