4. (20 points) moderately difficult Consider the following two player game I' = (N = (1, 2), (S, hie(12), (u;hie(12)). We say that the game I is strictly competitive, if for every strategy profile s = ($1, $2) ( S, x 52, wi ($1, $2) + uj ($1, $2) =0, if j. Establish the following: 2 (a) If s' = (sj, s;) is a NE , then for every player i, s; is a solution of max,, es, [min,, Es, u,(si, s, (b) If I has a NE, then each player's payoff is the same in all equilibria