(including intermediate states) of the composed system (so the product
construction of the three automata) showing a train approaching and finally
leaving the gate.}
-\begin{figure}[h]
+\begin{figure}[ht]
\centering
\includegraphics[width=.3\linewidth]{1a}
\caption{Timed transitions of the composed system}
$e_1=\langle s_1, a, \emptyset, [y:=0] s_2\rangle$\\
And we derive:\\
-\begin{align*}
- succ(e_1, succ(e_0, [0\leq x\leq 4, 0\leq y])) =&
- succ(e_1, ((([0\leq x\leq 4, 0\leq y]\wedge\emptyset)\Uparrow)\wedge\emptyset\wedge [x<1])[x:=0])\\
- =& succ(e_1, (([0\leq x\leq 4, 0\leq y]\Uparrow)\wedge\emptyset\wedge [x<1])[x:=0])\\
- =& succ(e_1, [0\leq x<1, 0\leq y][x:=0])\\
- =& succ(e_1, [x=0, 0\leq y])\\
- =& ((([x=0, 0\leq y]\wedge [x<1])\Uparrow)\wedge [x<1]\wedge [x<1])[y:=0]\\
- =& (([0\leq x<1, 0\leq y]\Uparrow)\wedge [x<1]\wedge [x<1])[y:=0]\\
- =& [0\leq x<1, y=0]
-\end{align*}
+\scalebox{.99}{\parbox{.5\linewidth}{%
+ \begin{align*}
+ succ(e_1, succ(e_0, [0\leq x\leq 4, 0\leq y])) =&
+ succ(e_1, ((([0\leq x\leq 4, 0\leq y]\wedge\emptyset)\Uparrow)
+ \wedge\emptyset\wedge [x<1])[x:=0])\\
+ =& succ(e_1, (([0\leq x\leq 4, 0\leq y]\Uparrow)
+ \wedge\emptyset\wedge [x<1])[x:=0])\\
+ =& succ(e_1, [0\leq x<1, 0\leq y][x:=0])\\
+ =& succ(e_1, [x=0, 0\leq y])\\
+ =& ((([x=0, 0\leq y]\wedge [x<1])\Uparrow)
+ \wedge [x<1]\wedge [x<1])[y:=0]\\
+ =& (([0\leq x<1, 0\leq y]\Uparrow)\wedge [x<1]\wedge [x<1])[y:=0]\\
+ =& [0\leq x<1, y=0]\\
+ \end{align*}}}
\subsection*{1.c}
\emph{Consider the timed automaton in figure 1 of the paper \emph{Timed
Automata} by Rajeev Alur. Give the zone automaton of the timed automaton, with
initial state $(s0, [x = 0, y = 0])$.}
+\begin{figure}[ht]
+ \centering
+ \includegraphics[width=.7\linewidth]{1c}
+ \caption{Zone automaton}
+\end{figure}
+
--- /dev/null
+digraph {
+ rankdir=LR;
+ s0a [label="s0a: {x=0,y=0}"]
+ s1a [label="s1a: {x=0,y=0}"]
+ s2 [label="s2: {0<=x=1,y=0}"]
+ s3 [label="s3: {0<=x=0,y=0}"]
+
+ s0b [label="s0b: {0<=x<1,0<=y<2}"]
+ s1b [label="s1b: {x=0,0<=y<2}"]
+
+ s0a -> s1a
+ s1a -> s2
+ s2 -> s3
+
+ s3 -> s0b
+ s0b -> s1b
+ s1b -> s3
+}