teaching machines

Wolf Hollow Virus

My children and I just finished reading Wolf Hollow by Lauren Wolk. As I closed the book, 9-year-old Lewis said that books that win awards are always sad. This book won an award.

I won’t go into any of the book’s merits. Rather, I will focus on one non-essential part of it that has been bothering the computer scientist part of me. Consider these selections from the early chapters:

My mother…took the three of us to Horne’s and had us sit for our portrait. The photographer told her that all portraits taken that month would be entered into a contest for a Kodak camera and a lifetime supply of film and processing…

Three weeks later, when a package arrived for my mother, we were astonished to find that it contained both our portrait…and the news that we had won the camera. It was also enclosed, along with a dozen spools of film to get us started and some special envelopes for sending them in to be developed…

Every time the photographs came back to us, there were two fresh rolls in the package. Kodak keeping its word.

Let’s think about that replacement strategy for a second.

  • After 0 developments, they have 12 rolls of film.
  • After 1 development, they have lost 1 roll but gained 2 more. In other words, they have 13 rolls of film.
  • After 2 developments, they have 13 – 1 + 2 = 14 rolls of film.
  • After 3 developments, they have 14 – 1 + 2 = 15 rolls of film.
  • After 4 developments, they have 15 – 1 + 2 = 16 rolls of film.
  • After 5 developments, they have 16 – 1 + 2 = 17 rolls of film.
  • After n developments, they have 12 + n rolls of film.

The book gets its title from the pits that hunters dug in the woods to trap wolves decades earlier. Pretty soon, Annabelle and her family will be the ones buried alive—by film canisters.

Comments

Leave a Reply

Your email address will not be published. Required fields are marked *