The Chaos Game

Example

For example of the Chaos Game, take four vertices,
(a3, b3) = (0, 1) (a4, b4) = (1, 1)
(a1, b1) = (0, 0) (a2, b2) = (1, 0)
the corners of the unit square, and take r = 1/2.
Suppose the random number generator begins by selecting the vertices in this order: 1, 3, 4, 3, 2.
Click the picture to see the first five points generated by this run of the chaos game.
If we continue, the points will fill in the square.
This should be plausible: we start with a point inside the unit square, and each move is half-way between where we are and a corner of the square, so we never leave the square.
Because we select the corners randomly, no part of the square is preferred over any other.
So since some parts of the square fill in, all parts must fill in.
Do you believe this argument?
Look at Chaos Game Problems to test your intuition.

Return to the Chaos Game.