ABSTRACT
Figure 13.1 shows three graphs that all look vaguely likeK5 but that are notK5. One of them may be familiar to you.
Figure 13.1. Three of K5’s first cousins.
1. Find the smallest number of colors needed to properly vertex-color each of the above graphs. Note that the vertices are drawn so that you can fill them in with colors, should you happen to have colored pens/pencils with you (and should you be willing to write in a book, unless of course you are working from a photocopied page, in which case there should be no problem… do you think it is possible to have a parenthetical remark that is longer than the parent sentence?).
