There is a prize of value M > 0. Two players spend resources competing for the prize. If P1 spends x1 > 0 and P2 spends x2 > 0, the probability that P1 wins the prize is p1 = ϕx1 / (ϕx1 + x2), where ϕ > 1. P2’s winning probability is p2 = 1−p1. Given strictly positive spendings, Pi’s expected utility is given by ui(xi, xj) = pi(xi,xj)M − xi.
(a) Find and draw each player’s best response function, and discuss what happens as ϕ changes.