Happy Birthday, Richard Guy!

Richard Guy turns 100 today. He is one of the authors of the classic text Winning Ways for your Mathematical Plays. At the CGT workshop at BIRS in 2011, he proposed a new subtraction game that I find myself thinking about on and off:

Given a pile of n tokens, and a subtraction set, S, each turn, you move to a new position, n (< n'), S', where either:

- Normal thing: S = S' and n' = n - s, for some s in S or,
- Weird thing: S' = { x } U S and n' = n - x and there are some y and z in S such that x = y + z.

I was alerted to an excellent birthday video for Richard, highlighting his work in Geometry.

Richard is one of the nicest people I've ever met, and he continues to be active in research today!