Exer. 16.1
Section 16.2 The secret behind magic circles
Exer. 16.2
Exer. 16.3
Exer. 16.4
Exer. 16.5
Exer. 16.6
Exer. 16.7
Exer. 16.8 A function from the quarter-plane to the naturals
Exer. 16.8 another solution
Exer. 16.8 yet another solution
Exer. 16.9
Exer. 16.10
Exer. 16.11
Exer. 16.12
Exer. 16.13
Exer. 16.14
Exer. 16.15
Exer. 16.16
Exer. 16.17
Exer. 16.18 - two solutions
Exer. 16.19