\begin{psmatrix}[rowsep=1.5cm]
&City&\\
{\tiny Shack} & House & {\Large Hotel}
\psset{arrows=<<-}
\ncline{1,2}{2,1}<{a}
\ncline{1,2}{2,2}>{b}
\ncline{1,2}{2,3}>{b}
\psset{arrows=-,linestyle=dotted}
\ncline{2,1}{2,2}
\ncline{2,2}{2,3}
\end{psmatrix}
