Math/CS 320 Fall 2008
Final Exam question 1

Draw n straight lines at random in the plane. "At random" means no two lines are parallel, and no three lines go through a single point. That's sometimes called "general position".

Here's a picture for n = 4.

These configurations have regions, vertices (where lines intersect) and edges. They're not quite the planar graphs we've studied, since some of the edges have just one vertex and "go off to infinity".

The first question on the exam will ask you to count some of the features of these configurations, and to relate the counts.

You can study for the exam by computing some examples and trying to anticipate what I will ask.