Martin's maximum revisited

We present several results relating the general theory of the stationary tower forcing developed by Woodin with forcing axioms. The main results is that the forcing axiom MM^{++} (also known as MM^{+\omega_1}) decides the \Pi_2-theory of H_{\omega_2} with respect to stationary set preserving forcings. We argue that this is a close to optimal generalization to H_{\omega_2} of Woodin’s absoluteness results for L®.