\begin{tikzpicture}[->,>=stealth,shorten >=1pt,auto,scale=0.6,transform shape]
	% x node set with absolute coordinates
	\node[state] (A) at (0,0) {$A$};
	\node[dstate] (B) at (-2,-1) {$B$};
	\node[dstate] (C) at (2,-1) {$C$};
	\node[state] (D) at (-3,-2.5) {$D$};
	\node[state] (E) at (-1.5,-2.5) {$E$};
	\node[state] (F) at (-1,-4) {$F$};
	\node[state] (G) at (3,-2.5) {$G$};
	\node[state] (H) at (1.5,-2.5) {$H$};
	\node[state] (I) at (1,-4) {$I$};
	% Directed edge
	\path (A) edge (B);
	\path (A) edge (C);
	\path (B) edge (D);
	\path (B) edge (E);
	\path (E) edge (F);
	\path (A) edge (F);
	\path (C) edge (G);
	\path (C) edge (H);
	\path (H) edge (I);
	\path (A) edge (I);
	% Bidirected edge
	%\path[bidirected] (A) edge[bend left=60] (C);
\end{tikzpicture}
