He might be interested in this book which I liked on game AI programming (I copy/pasted what's below from my journal at use.perl.org). Since you said he maybe needed reinforcement in math, he might be interested in the basic trigonometry used in the early parts of the book as they're applied to the AI algorithms (pursuit, fleeing, etc.).

I'm reading Programming Game AI by Example. I think that if you're an intermediate programmer who knows C++, and have an interest in computer games (even if you just play them, like me), you'd probably like it. It's really practically oriented, like a tutorial, but at the same time his explanations are based on sensible designs (in the sense of "ok, maybe you wouldn't do exactly this in a real game, but this is the basic idea"). It's not for you if you're looking for an academic, theoretical book. I've only read the first three chapters, but so far so good. I really liked chapters 2 (finite state machines, where he uses an example of Miner Bob who goes from the mine to the saloon ("ah's mighty thusty!") and the bank and home to the li'l lady) and chapter 3 (steering behaviors: seek, flee, pursuit, evade, object avoidance, wall avoidance, etc. If you want to know more, he mentions an article called Steering Behaviors For Autonomous Characters a few times in the book, which also contains a lot of links in its references section.).