+ St' is the Fermi function, and the fitnesses are defined as f = Ax. The above comparison of the pair of players takes place w.p. 1 — u. Instead, w.p. u one of them adopts a random strategy. Let us calculate directly the change of the frequency of k-players due to selection Axr1 in state X. The n

In the W-F model, each player of a new (non-overlapping) generation chooses a parent from the previous generation with probability (abbreviated as w.p.) proportional to the parent's payoff. The offspring inherits the parent's strategy w.p. 1 —u, or adopts a random strategy w.p. The expected number