Interesting, a friend of mine posted that same link on facebook a few days ago.
I read through the whole thing and the problems I have with it are as follows:
- It is based on a standard infectious disease "SIR" model, which I think fails to adequately take into account all the variables in a real life zombie outbreak.
- It only includes cases where beta > alpha, i.e. the zombies are better at killing humans than vice versa.
- And finally, the Zeta R term in the Z' equation makes dead bodies (zombies who have been headshotted or decapitated) return to being zombies. This is fine for something like Urban Dead, but I would hope that headshotted zombies do not come back to life in a "real" zombie outbreak.
All in all, this is fine for a scientific paper on a fictional subject, but it does not satisfy me as an adequate model of what zombies should be like.