Players A, B and C are supposed to build a flood wall. It takes at least two of the three to pitch in to get the job done. Each one receives a benefit of 2 if the wall gets build but pitching in causes a cost of 1 for person pitching in.

a) Is there is first, second or last mover advantage if the game is played sequentially (since it is symmetric for all players, just show the tree for the sequence: A, B, C). what is the rollback equilibrium?

b) Also show the game when it is played simultaneously. Identify all the Nash equilibria.