\documentclass[fleqn,leqno]{article}
\usepackage{hypertlabook}
\pdftitle{Answer}
\begin{popup}
\subsection*{Answer}

\vspace{.5em}

% \newcommand{\hdskstate}[3]{\left[\!\begin{array}{l@{\,\,}c@{\,\,}c}
%                         p & = & #1 \\ c & = & #2 \\ box & = & #3
%                         \end{array}\!\right]}
\newcommand{\hdskstate}[4]{%
\begin{array}{c}
\left[\!\begin{array}{l@{\,\,}c@{\,\,}c}
                        p & = & #1 \\ c & = & #2 \\ box & = & #3
                        \end{array}\!\right] \V{1.5}
%       \rule{2em}{.6pt} \V{4}
       p\oplus c = #4 \V{-1.7}
\end{array}
}
 \[
  \begin{noj}
  \hdskstate{0}{0}{<<\,>>}{0} \;->\; \hdskstate{1}{0}{<<"widget">>}{1} \;->\; 
  \hdskstate{1}{1}{<<\,>>}{0} \;->\; \V{5}
    \s{2}\hdskstate{0}{1}{<<"widget">>}{1} \;->\; 
   \hdskstate{0}{0}{<<\,>>}{0} \;->\; 
            \cdots
  \end{noj}
 \]
\mbox{}

\end{popup}
\makepopup