\begin{figure}

\numberrules

Execution of a "switch" statement:
\begin{pannel}

\irule
        G, E |- a, M \evalexpr n, \tr, M_1 \\
        G, E |- "select_switch" (n,\ls), M_1 \evalstmt \out, \tr_2, M_2 
        --------------------------------------------------
        G, E |- "switch" (a)\ls, M \evalstmt  "outcome_switch" (\out), \cat {\tr_1} \tr_2, M_2
\end \label{rule:28}
\end{pannel}

Execution of a "switch" branch:
\begin{pannel}

\irule
        G, E |- s, M \evalstmt \out, \tr, M'
        --------------------------------------------------
        G, E |- "default" (s) , M \evalstmt \out, \tr, M'
\end \label{rule:29}

\\
\irule
        G, E |- s, M \evalstmt "Out_normal", \tr_1, M_1 \\
        G, E |- \ls, M \evalstmt \out, \tr_2, M_2
        --------------------------------------------------
        G, E |- "case" (n,s,\ls), M \evalstmt \out', \tr_2, M_2
\end \label{rule:30}
\\
\irule
        G, E |- s, M \evalstmt \out, \tr, M' & \out \not= "Out_normal"
        --------------------------------------------------
        G, E |- "case" (n,s,\ls), M \evalstmt \out', \tr, M'
\end \label{rule:31}

\end{pannel}
\caption{Dynamic semantics of switch statement}
\label{fig:dynsem4}
\end{figure}