On some geometry and equivalence classes of normal form games

Equivalence classes of normal form games are defined using the geometry of correspondences of standard equilibiurm concepts like correlated, Nash, and robust equilibrium or risk dominance and rationalizability. Resulting equivalence classes are fully characterized and compared across different equilibrium concepts for 2 x 2 games. It is argued that the procedure can lead to broad and game-theoretically meaningful distinctions of games as well as to alternative ways of viewing and testing equilibrium concepts. Larger games are also briefly considered.