% Figure 1.3 begins

\def\hyedg{\smash{\hbox to 20pt{%
\vrule height0.5pt width20pt depth0.5pt\hskip -10pt%
\hbox to 0pt{\hidewidth%
\vrule height10.7pt depth10.7pt width0.4pt%
\hidewidth}%
\hskip 10pt}}}

\def\vyedg{\hbox to 1pt{%
\vrule height10pt width1pt depth10pt\hskip -0.5pt%
\hbox to 0pt{\hidewidth%
\vrule height0.2pt depth0.2pt width21.4pt%
\hidewidth}%
\hskip 0.5pt}}

\def\yface{\hglue10pt\hbox to 0pt{%
\hidewidth%
\lower\fontdimen22\textfont2\hbox{$\bullet$}%
\hidewidth%
}\hglue10pt}

\midinsert
\medskip

\centerline{
\vbox{\offinterlineskip
\hbox{\vt \hedg \vt \hedg \vt \hedg \vt \hedg \vt \hedg \vt}
\hbox{\vedg \yface \vyedg \yface \vyedg \yface \vyedg \yface \vyedg \yface \vedg}
\hbox{\vt \hyedg \vt \hyedg \vt \hedg \vt \hedg \vt \hyedg \vt}
\hbox{\vedg \yface \vyedg \yface \vedg \phe \pvt \phe \vedg \yface \vedg}
\hbox{\vt \hyedg \vt \hyedg \vt \hedg \vt \hedg \vti{p} \hedg \vt}
\hbox{\vedg \yface \vyedg \yface \vyedg \yface \vyedg \yface \vedg \phe \pvt}
\hbox{\vt \hedg \vt \hedg \vt \hedg \vt \hedg \vt \phe \pvt}
}}

\nobreak
\smallskip
\nobreak

\centerline{\bf Figure 1.3}

\smallskip
\endinsert

% Figure 1.3 ends
