\documentclass{standalone}
\usepackage{tikz}
\begin{document}
	\begin{tikzpicture}
\coordinate (1) at (0,10) {};
\coordinate (2) at (-3,10) {};
\coordinate (3) at (-3,8) {};
\coordinate (4) at (-4,8) {};
\coordinate (5) at (-4,7) {};
\coordinate (6) at (-5,7) {};
\coordinate (7) at (0,10.05) {};
\coordinate (8) at (-3.05,10.05) {};
\coordinate (9) at (-3.05,9.05) {};
\coordinate (10) at (-4.05,9.05){};
\coordinate (11) at (-4.05,7.05){};
\coordinate (12) at (-5,7.05){};
\draw [blue,thick](1) -- (2);
\draw [blue,thick](3) -- (2);
\draw [blue,thick](3) -- (4);
\draw [blue,thick](5) -- (4);
\draw [blue,thick](5) -- (6);

\node at (-3.5,10) {$(a,i)$};
\node at (-2.2,8.8) {$(a,i -1)$};
\node at (0.3,10.3) {$(b,i)$};

\node at (-3,10.3) {$C$};
\node at (-3.3,9.5) {$B$};
\node at (-3.3,8.5) {$A$};

\draw [fill = black] (1) circle (0.050);
\draw [fill = black] (2) circle (0.050);
\draw [fill = black] (-3,9) circle (0.050);

\draw [red,thick](8) -- (9) ;
\draw [red,thick](9) -- (10) ;
\draw [red,thick](7) -- (8) ;
\draw [red,thick](10) -- (11) ;
\draw [red,thick](12) -- (11) ;
\coordinate (1') at (5,10) {};
\coordinate (2') at (5,9) {};
\coordinate (25) at (2,9) {};
\coordinate (3') at (2,8) {};
\coordinate (4') at (1,8) {};
\coordinate (5') at (1,7) {};
\coordinate (6') at (0,7) {};
\coordinate (7') at (5,10.05) {};
\coordinate (8') at (1.95,10.05) {};
\coordinate (9') at (1.95,9.05) {};
\coordinate (10') at (0.95,9.05){};
\coordinate (11') at (0.95,7.05){};
\coordinate (12') at (0,7.05){};
\draw [blue,thick](1') -- (2');
\draw [blue,thick](25) -- (2');
\draw [blue,thick](25) -- (3');
\draw [blue,thick](3') -- (4');
\draw [blue,thick](5') -- (4');
\draw [blue,thick](5') -- (6');

\node at (1.5,10) {$(a,i)$};
\node at (2.8,8.8) {$(a, i - 1)$};
\node at (5.3,10.3) {$(b,i)$};
\node at (5.3,8.8) {$(b,i - 1)$};

\node at (2,10.3) {$C$};
\node at (1.7,9.5) {$B$};
\node at (1.7,8.5) {$A$};

\draw [fill = black] (1') circle (0.050);
\draw [fill = black] (2') circle (0.050);
\draw [fill = black] (2,9) circle (0.050);
\draw [fill = black] (2,10) circle (0.050);


\draw [red,thick](8') -- (9') ;
\draw [red,thick](9') -- (10') ;
\draw [red,thick](7') -- (8') ;
\draw [red,thick](10') -- (11') ;
\draw [red,thick](12') -- (11') ;

\end{tikzpicture}
\end{document}
