A recursive algorithm can be written to draw a spiral, starting in the middle and expanding outward with each revolution. A similar algorithm can be written to draw a "spirally increasing pseudo-square" like that shown in Figure 7-16 . Such an algorithm could be used for a search pattern to search for a lost object, or for a robotic lawn mower that could be left in the middle of a large field and then programmed to start mowing the field from the center outward. Create a "recursive Zamboni" Alice world with a snow background and a Zamboni with a recursive method to make the Zamboni follow the spirally increasing pseudo-square pattern just described. A Zamboni is the machine that is used to clean an ice-skating rink, such as at a hockey game between periods. The Alice vehicle gallery has a Zamboni.
