Chapter 9 Exercise 9.34

The rule F ->

means that F can be replaced by nothing.

Chapter 9 Listing 9.7

when setposition is called to restore the turtle's position and heading to a previously stored location, the tail should be up. so Lines 16 and following should read:

        elif cmd == ']':
            pos,head = stateSaver.pop()
            aTurtle.up()
            aTurtle.setposition(pos)
            aTurtle.setheading(head)
            aTurtle.down()

Chapter 9 -- Page 314 -- Listing 9.4

The recursive calls to sierpinski in lines 14,15, and 16 have an extra comma at the end of the parameter list as shown below.

sierpinski(myTurtle,p1,midPoint(p1,p2),midPoint(p1,p3),depth-1,)
sierpinski(myTurtle,p2,midPoint(p2,p3),midPoint(p2,p1),depth-1,)
sierpinski(myTurtle,p3,midPoint(p3,p1),midPoint(p3,p2),depth-1,)

This is a typo.  Although these extra commas do not cause any syntactic problem, they should be removed.