Draw trees of nested CES functions with LaTeX

The following examples should work right away if

\usepackage{pstricks,pstricks-add,pst-node,pst-tree}

appears in the preamble of the latex code. The code cannot directly be compiled to a PDF via pdflatex. As pstricks generates PostScript code that needs to be included later on, the detour via dvi and ps has to be taken.

First simple example:

 \pstree[treemode=D,levelsep=10ex,nodesep=2pt,angleB=90]{
      \TR{$PX$}
      \psarcn(0,0){.4cm}{-57}{-123}
      \uput{.4cm}[-35](0,0){{$\gamma_s=5$}} 
    }{
      \TR[name=a1]{$P_1$}
      \pstree{ 
        \TR{$P_{va}$}
        \psarcn(0,0){.4cm}{-57}{-123}
        \uput{.4cm}[-35](0,0){{$\gamma_{va}=6$}}  
      }{
        \TR[name=p1]{$P_1$}
        \TR[name=p3]{$P_2$}
      }
    }

Second (still simple) example:

\pstree[treemode=D,levelsep=10ex,nodesep=2pt,angleB=90]{
      \TR{$C^0$}
      \psarcn(0,0){.4cm}{-22}{-158}
      \uput{.5cm}[-5](0,0){{$\gamma^0$}} 
    }{
      \TR[name=a1]{$P_1$}
      \TR{$P_2$}
      \pstree{ 
        \TR{$C_1^1$}
        \psarcn(0,0){.4cm}{-57}{-123}
        \uput{.4cm}[-35](0,0){{$\gamma^1$}}  
      }{
        \TR[name=p1]{$P_1$}
        \TR[name=p3]{$P_3$}
      }
      \pstree{ 
        \TR[name=z1]{$C_2^1$}
        \psarcn(0,0){.4cm}{-57}{-123}
        \uput{.4cm}[-35](0,0){{$\gamma^2$}}  
      }{
        \TR[name=A]{$P_4$}
        \TR[name=B]{$\ldots$}
      }
    }
\ncbox[linearc=.2,boxheight=1.2,linestyle=dashed,nodesep=.2,linecolor=gray]{A}{B}
\ncbox[linearc=.2,linestyle=dashed,nodesep=.2,linecolor=gray]{B}{B}
\ncbox[linearc=.2,boxheight=1.2,linestyle=dashed,nodesep=.1,linecolor=gray]{p1}{p3}
\ncbox[linearc=.2,boxheight=1.2,linestyle=dashed,nodesep=.1,linecolor=gray]{a1}{z1}