Applet
Instructions:
1.) Create a graph either by adding vertices and edges yourself or generate a random plane graph (up to 20 vertices) automatically, using 'Random Graph'.
2.) Check if the graph is plane using 'Check if Plane'; if your graph is not plane you can remove vertices (and corresponding edges) or start over with 'Clear'.
3.) Color the graph using 'Color graph', it will automatically check if the graph is plane.
4.) Click on the screen again for any alternate colorings.
5.) Clear the screen and try again!
Note: After clicking a button, you must click on the screen.