Here is another quick pathway fragment I needed today. This won’t scale well because I’ve used some fixed dimensions eg the width of the lines and the size of the text. But these are easily adjusted if you want to size the figure differently. The node distance = 2.5cm gives the sizes for the arrows except for v3. One might be able to calculate the some of the fixed sizes based on the node distance but I didn’t have time to investigate this.

```
``````
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{tikzpicture}[>=latex',node distance = 2.5cm]
\node (S) {\scalebox{1.4}{$S$}};
\node [left of = S] (Xo) {};
\draw[->,line width = 1.2pt] (Xo) to node[above] {\scalebox{1.3}{$v_1$}} (S);
\node [right of = S] (X1) {};
\draw[->,line width = 1.2pt] (S) to node[above] {\scalebox{1.3}{$v_2$}} (X1);
\node[above of = S, node distance = 1.5cm] (V3) {};
\draw[-|,line width = 1.2pt] (S) to (V3) {};
\node[left of = V3, node distance = 1.25cm] (Xa) {};
\node[right of = V3, node distance = 1.25cm] (Xb) {};
\draw[->,line width = 1.2pt] (Xa) to node[above] {\scalebox{1.3}{$v_3$}} (Xb);
\end{tikzpicture}
\end{document}
```