\begin{tikzpicture}[x=1ex,y=1ex,baseline={([yshift=-.5ex]current bounding box.center)}]
    \coordinate (vm);
    \coordinate [left=.7 of vm] (v0);
    \coordinate [right=.7 of vm] (v1);
    \coordinate [above=.7 of v0] (v2);
    \coordinate [above=.7 of v1] (v3);
    \draw (v0) circle(.7);
    \draw (v1) circle(.7);

    \draw (v3) arc(0:180:.7) (v2);
    \filldraw (vm) circle (1pt);
    \filldraw (v2) circle (1pt);
    \filldraw (v3) circle (1pt);
\end{tikzpicture}%
