\mathfig{.6}{tempkw/left-marked-antirefinements}

$$

\begin{tikzpicture}

\fill (0,0) circle (.1);

\draw (0,0) -- (2,0);

\draw (1,0.1) -- (1,-0.1);

\draw [->,red] (1,0.25) -- (1,0.75);

\fill (0,1) circle (.1);

\draw (0,1) -- (2,1);

\end{tikzpicture}

\qquad

\begin{tikzpicture}

\fill (0,0) circle (.1);

\draw (0,0) -- (2,0);

\draw (1,0.1) -- (1,-0.1);

\draw [->,red] (1,0.25) -- (1,0.75);

\fill (0,1) circle (.1);

\draw (0,1) -- (1,1);

\end{tikzpicture}

\qquad

\begin{tikzpicture}

\fill (0,0) circle (.1);

\draw (0,0) -- (3,0);

\foreach \x in {0.5, 1.0, 1.25, 1.5, 2.0, 2.5} {

	\draw (\x,0.1) -- (\x,-0.1);

}

\draw [->,red] (1,0.25) -- (1,0.75);

\fill (0,1) circle (.1);

\draw (0,1) -- (2,1);

\foreach \x in {1.0, 1.5} {

	\draw (\x,1.1) -- (\x,0.9);

}

\end{tikzpicture}

$$