COX RINGS OF RATIONAL SURFACES AND REDUNDANT BLOW-UPS.

We prove that the redundant blow-up preserves the finite generation of the Cox ring of a rational surface under a suitable assumption, and we study the birational structure of Mori dream rational surfaces via redundant blow-ups. It turns out that the redundant blow-up completely characterizes birational morphisms of Mori dream rational surfaces with anticanonical Iitaka dimension 0. As an application, we construct new Mori dream rational surfaces with anticanonical Iitaka dimension 0 and -8 of arbitrarily large Picard number. [ABSTRACT FROM AUTHOR]