Suppose we start with n vertices, choose one special vertex and then draw edges from the special vertex to every other vertex. The graph we would obtain is called the star on n vertices, S_{n}. Figure 18.1 shows the star on ten vertices, S_{10}.
 

Java Web Start Activity:
To get examples of star graphs, launch the Java Web Start application
by clicking on the link below this paragraph. Once the application is
running, click on the
+ button to increase the number of vertices. The
 button decreases the number of vertices.
Petersen activity:
To get a star graph in the Petersen program use the menu options
Graph  Named Graph  Trees  Star. Take a look at a few
of the graphs S_{n} for other values of n
and then answer the questions below.
 

Use the Petersen program to examine some star graphs and answer the following questions:
 What is the chromatic number of S_{3}, S_{5}, S_{8}
 Are stars bipartite ?
 Which complete bipartite graph is isomorphic to S_{n}?
Answers
© C. Mawata