%% 
%%  An UIT Edition example
%% 
%%  Example 07-06-6 on page 139.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{exasymbol}
\pagestyle{empty}
\setlength\textwidth{177.70511pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\usepackage{stmaryrd,lucidabr}
\StopShownPreambleCommands
\begin{document}
\[ \left\llbracket
  \bigbox_{i\inplus I}^{a \varoplus b} P_i
\right\rrbracket \]
\end{document}