Question 1.46

1. Add up the numbers you get for the valences of the vertices in Figure 1.6.
2. Add up the numbers you get for the valences of the vertices in Figure 1.7.
3. Add up the numbers you get for the valences of the vertices in Figure 1.8a.
4. Describe the pattern you see in your answers for parts (a) through (c).
5. Show that the pattern describes a fact that is true for any graph. (Hint: How many endpoints does an edge have?)