Karel J Robot: A Gentle Introduction to the Art of Object-Oriented Programming in Java

Abstract

Figure 1-1 is a map illustrating the structure of the robot world, whose shape is a great flat plane with the standard north, south, east, and west compass points. The world is bounded on its west side by an infinitely long vertical wall extending northward. To the south, the world is bounded by an infinitely long horizontal wall extending eastward. These boundary walls are made of solid neutronium, an impenetrable metal that restrains robots from falling over the edges of the world.