\begin{tikzpicture}[auto,scale=\rtree,transform shape]
% x node set with absolute coordinates
\node (d) at (-1.5,0) [label=below:$D|C_1C_2$,point];
\node (x11) at (0,0) [label=below:$X_1^{(1)}|U$,point];
\node (x21) at (1.5,0) [label=below:$X_2^{(1)}|X_1^{(1)}$,point];
\node (c1) at (3,0) [label=below:$C_1|X_2^{(1)}$,point];
\node (c2) at (4.5,0) [label=below:$C_2|X_2^{(2)}$,point];
\node (x22) at (6,0) [label=below:$X_2^{(2)}|X_1^{(2)}$,point];
\node (x12) at (7.5,0) [label=below:$X_1^{(2)}|U$,point];

\node (i1) at (0.75,1) [label=left:$i_1$,point];
\node (i2) at (2,2) [label=left:$i_2$,point];
\node (i3) at (1.5,4) [label=left:$i_3$,point];
\node (i4) at (4,5) [label=left:$i_4$,point];
\node (i5) at (5,6) [label=left:$i_5$,point];
\node (r) at (6,7) [label=left:$r$,point];
\node (h) at (6,8) [label=left:$h(U)$,point];

% Directed edge
\path (x11) edge node[left] {$X_1U$} (i1);
\path (x21) edge node[right] {$X_1X_2$} (i1);
\path (c1) edge node[right] {$C_1X_2$} (i2);
\path (i1) edge node[left] {$\bcancel{X_1}X_2U$} (i2);
\path (i2) edge node[right] {$\bcancel{X_1}\bcancel{X_2}C_1U$} (i3);
\path (d) edge node[left] {$C_1C_2$} (i3);
\path (c2) edge node[right] {$C_2X_2$} (i4);
\path (i3) edge node[left] {$\bcancel{X_1}\bcancel{X_2}C_2U$} (i4);
\path (x22) edge node[right] {$X_1X_2$} (i5);
\path (i4) edge node[left] {$\bcancel{X_1}X_2U$} (i5);
\path (x12) edge node[right] {$X_1U$} (r);
\path (i5) edge node[left] {$X_1U$} (r);
\path (r) edge node[right] {$U$} (h);
%\path (x1) edge node[left] {$XA$} (i1);
%\path (c1) edge node[right] {$XC_1$} (i1);
%\path (d) edge node[right] {$C_1C_2$} (i3);
%\path (i1) edge node[left] {$XC_1A$} (i3);
%\path (i2) edge node[right] {$C_1C_2$} (i3);
%\path (i3) edge node[left] {$XAC_2$} (i4);
%\path (c2) edge node[right] {$XC_2$} (i4);
%\path (i4) edge node[left] {$XA$} (r);
%\path (x2) edge node[right] {$XA$} (r);
%\path (r) edge node[right] {$A$} (h);
%\draw[dotted] (p) -- (ep);
%\draw[dotted] (c) -- (ec);
% Bidirected edge
%\path[bidirected] (A) edge[bend left=60] (C);
%\node at ($(1)!.5!(2)$) {\ldots};
\end{tikzpicture}
