\begin{tikzpicture}[->,>=stealth,shorten >=1pt,auto,scale=0.6, transform shape]
	% x node set with absolute coordinates
	\node[state] (A) at (6,0) {$A$};
	\node[dstate] (X) at (1.5,0) {$X$};
	\node[dstate] (Y) at (3.75,0) {$Y$};
	\node[state] (C1) at (0,1.5) {$C_1$};
	\node[state] (C2) at (0,-1.5) {$C_2$};
	% Directed edge
	\path (A) edge (Y);
	\path (Y) edge (X);
	\path (X) edge (C1);
	\path (X) edge (C2);
	% Bidirected edge
	%\path[bidirected] (A) edge[bend left=60] (C);
\end{tikzpicture}
