\documentclass{article}
\usepackage{com.braju.graphicalmodels}

\catcode`\@=11%

\pagestyle{empty}

\begin{document}
\TeXtoEPS

\LARGE
\psset{unit=10mm,arrowscale=1.5,linewidth=1.5pt}
\begin{pspicture}(0,0)(7,10)%\showgrid
  \SpecialCoor

  \rput(4,9){\GM@node[observed=false]{alpha}} \GM@label[angle=0]{alpha}{$\alpha$}

  \rput(2,7){\GM@node[observed=false]{z1}} \GM@label[angle=225]{z1}{$z_1$}
  \rput(4,7){\GM@node[observed=false]{zi}} \GM@label[angle=225]{zi}{$z_i$}
  \rput(6,7){\GM@node[observed=false]{zN}} \GM@label[angle=225]{zN}{$z_N$}

  \rput(2,5){\GM@node[observed=true]{x1}} \GM@label[angle=145]{x1}{$x_1$}
  \rput(4,5){\GM@node[observed=true]{xi}} \GM@label[angle=145]{xi}{$x_i$}
  \rput(6,5){\GM@node[observed=true]{xN}} \GM@label[angle=145]{xN}{$x_N$}


  \rput(4,3){\GM@node[observed=false]{lambda}} \GM@label[angle=0]{lambda}{$\beta$}


  \ncline[arrows=->]{lambda}{x1}
  \ncline[arrows=->]{lambda}{xi}
  \ncline[arrows=->]{lambda}{xN}

  \ncline[arrows=->]{z1}{x1}
  \ncline[arrows=->]{zi}{xi}
  \ncline[arrows=->]{zN}{xN}

  \ncline[arrows=-]{z1}{zi}
  \ncline[arrows=-]{zi}{zN}
  \ncarc[arcangle=25,arrows=-]{z1}{zN}

  \ncline[arrows=-]{x1}{xi}
  \ncline[arrows=-]{xi}{xN}
  \ncarc[arcangle=-25,arrows=-]{x1}{xN}

  \ncline[arrows=->]{alpha}{z1}
  \ncline[arrows=->]{alpha}{zi}
  \ncline[arrows=->]{alpha}{zN}



\end{pspicture}

\endTeXtoEPS
\end{document}