\begin{tikzpicture}[x=0.92cm, y=0.92cm,
  vtx/.style = {circle, fill = black, inner sep = 1.2pt},
  newv/.style = {circle, draw = black, fill = white, thick, inner sep = 1.6pt},
  bg/.style = {gray, thick},
  lst/.style = {black, line width = 0.9pt},
  inz/.style = {black, densely dotted, line width = 1.1pt},
  hull/.style = {gray, dash pattern = on 2pt off 2pt, rounded corners = 7pt},
  lab/.style = {font = \small},
  ttl/.style = {font = \small}]
\def\lowidentbackground{%
  \draw[thick] (0, 0) ellipse (2.05 and 0.95);
  \node[vtx] (p1) at (-1.3, 0.15) {};
  \node[vtx] (p2) at (-0.65, -0.5) {};
  \node[vtx] (p3) at (0, 0.4) {};
  \node[vtx] (p4) at (0.65, -0.45) {};
  \node[vtx] (p5) at (1.35, 0.15) {};
  \draw[bg] (p1) -- (p2);
  \draw[bg] (p2) -- (p4);
  \draw[bg] (p3) -- (p5);
  \draw[bg] (p4) -- (p5);
  \node[lab] at (1.75, -0.95) {$V'$};
  \node[lab, gray] at (-2.15, -0.75) {$B'_s$};}
\begin{scope}
  \lowidentbackground
  \draw[hull] (-1.55, 1.75) rectangle (1.55, 2.55);
  \node[vtx] (z1) at (-1, 2.15) {};
  \node[vtx] (z2) at (0, 2.15) {};
  \node[vtx] (z3) at (1, 2.15) {};
  \node[lab] at (-1.9, 2.15) {$Z_0$};
  \draw[lst] (z1) -- (p1);
  \draw[lst] (z1) -- (p3);
  \draw[lst] (z2) -- (p3);
  \draw[lst] (z2) -- (p4);
  \draw[lst] (z3) to[bend right = 10] (p5);
  \draw[lst] (z3) to[bend left = 10] (p5);
  \draw[inz] (z2) to[bend left = 35] (z3);
  \node[lab] at (0.5, 2.95) {possible occurrence inside $Z_0$};
  \node[ttl] at (0, -1.55) {$B_{\Pi_s}$ near $Z_0$};
\end{scope}
\draw[-{Stealth[length = 2.2mm]}, thick] (2.35, 1.1) -- node[lab, above] {identify}
  node[font = \scriptsize, below, align = center] {no internal\\occurrence} (3.35, 1.1);
\begin{scope}[shift = {(5.7, 0)}]
  \lowidentbackground
  \node[newv, label = {[lab]above:$o$}] (o) at (0, 2.15) {};
  \draw[lst] (o) -- (p1);
  \draw[lst] (o) to[bend right = 9] (p3);
  \draw[lst] (o) to[bend left = 9] (p3);
  \draw[lst] (o) -- (p4);
  \draw[lst] (o) to[bend right = 6] (p5);
  \draw[lst] (o) to[bend left = 6] (p5);
  \node[lab] at (0, -1.55) {$B_{\Pi_s}/Z_0$};
  \node[lab] at (0, -2.15) {list length $\Pois(D \hat z(s))$};
\end{scope}
\draw[-{Stealth[length = 2.2mm]}, thick] (8.05, 1.1) -- node[lab, above] {compare} (9.05, 1.1);
\begin{scope}[shift = {(11.4, 0)}]
  \lowidentbackground
  \node[newv, label = {[lab]above:$o$}] (o) at (0, 2.15) {};
  \draw[lst] (o) -- (p2);
  \draw[lst] (o) -- (p5);
  \node[lab] at (0, -1.55) {$B''$};
  \node[lab] at (0, -2.15) {list length $\Pois(\hat z(s))$};
\end{scope}
\end{tikzpicture}