\documentclass{ppex}
\nonstopmode
\usepackage [arrow]{xy}
\pagestyle{empty}
\setlength\textwidth{183.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage [arrow]{xy}
\[\begin{xy} <6mm,0mm>:
  (0,0)*+\txt\small{Origin}="O"
  \ar@{.>>}
    `r  (3,2) *\dir{*}*+!DL{\mathrm{P_1}} ^-1
    `   (-2,2)*\dir{*}*+!U{\mathrm{P_2}}  ^2
    `_dr(-2,0)*\dir{*}*+!U{\mathrm{P_3}}  _(.3)3
    `dr^r "O"                             _(.8)4
          "O"                             ^-(.2)5
\end{xy}\]
\end{document}
