A Preemptive Apology

The volume of emails I have been receiving regarding VDGF has been accelerating steadily since its publication in July, 2021.
I'm afraid I simply cannot keep up. Therefore, let me preemptively apologize if your email does not receive a reply.
But rest assured that I very much appreciate all your comments and especially your corrections.
If you submit a correction, it will ultimately appear (with attribution!) in the Dynamic Errata.

An increasing number of people have written to ask me if I can make the solutions available to them.
I'm afraid I cannot, for the simple reason that I do not have the solutions myself.
As I composed the exercises, I scribbled drawings and calculations on scraps of paper, but I kept no permanent record of my efforts.

Please email CORRECTIONS to
Please email COMMENTS and QUESTIONS to