Acknowledgements
The images in Chapters 6, 42, and 47 are by Stella Hui. The definitions of Q , Q1 , and S in Chapter 7 were improved by a suggestion from Andrea Arbaci and Jay Foad. The GIF at the beginning of Chapter 38 is by André Karwath in Wikimedia Commons. The 3-door image at the beginning of Chapter 48 is by Cepheus in Wikimedia Commons. |