Line attribute

You can draw not only solid lines but also dotted lines and dash lines. epic.sty and eepic.sty define several commands for them. If you want to use

\dashline[65]{3}(x1,y1)(x2,y2)

to draw lines, use \brush command before corresponding \match command.

\brush{\dashline[65]{3}}

If you write

\begin{bipartite}{2cm}{1.5cm}{2cm}{3mm}{2mm}
\leftnode{xxx}
\leftnode{yyy}
\leftnode{zzz}
\rightnode{aaa}
\rightnode{bbb}
\rightnode{ccc}
\match{xxx}{ccc}
\brush{\dottedline{3}}
\match{zzz}{bbb}
\end{bipartite}

you get
$\begin{bipartite}{2cm}{1.5cm}{2cm}{3mm}{2mm} \leftnode{xxx} \leftnode{yyy} \left... ...de{ccc} \match{xxx}{ccc} \brush{\dottedline{3}} \match{zzz}{bbb} \end{bipartite}$
.