1 \documentclass{article
}
7 \newcommand{\ra}{\rightarrow}
8 \newcommand{\un}{\text{ \textsf{U
} }}
9 \newcommand{\ev}{\lozenge}
10 \newcommand{\al}{\square}
11 \newcommand{\nx}{\bigcirc}
21 s_2
\ra s_4
\overline{\ra s_5
}\\
23 s_2
\ra s_4
\overline{\ra s_5
}\\
24 \phi_3=
\nx\neg c
\rightarrow\nx\nx c &
25 s_2
\ra s_4
\overline{\ra s_5
}\\
27 \text{Impossible. $a$ only holds in $s_1$ and in $s_5$.
}\\
28 &
\text{$s_1$ we can only leave through a state where $
\neg a$
}\\
29 &
\text{$s_5$ we can not reach through $s_1$ without passing
30 through a $
\neg a$ state
}\\
31 \phi_5=a
\un\al(b
\vee c) &
32 s_1
\ra s_4
\overline{\ra s_5
}\\
33 \phi_6=(
\nx\nx b)
\un(b
\vee c) &
34 s_2
\ra s_4
\overline{\ra s_5
}