\begin{tikzpicture}[>=latex,join=bevel,] % \node (c) at (81bp,18bp) [draw,record] { C = \$$\backslash$varnothing\$ | meuh}; \node (a) at (81bp,78bp) [draw,ellipse] {a}; \node (b) at (81bp,177bp) [draw,ellipse] {b}; \node (d) at (81bp,127bp) [draw,ellipse] {d}; \draw [->] (a) ..controls (81bp,66bp) and (81bp,56bp) .. (c); \draw [->] (b) ..controls (81bp,163bp) and (81bp,153bp) .. (d); \draw [->] (d) ..controls (81bp,113bp) and (81bp,103bp) .. (a); % \end{tikzpicture}