An F-theory dual of a nonsupersymmetric orientifold is considered. It is
argued that the condensation of both open and closed string tachyons in the
orientifold corresponds to the annihilation of branes and anti-branes in the
F-theory dual. The end-point of tachyon condensation is thus expected to be the
vacuum of Type-IIB superstring. Some speculations are presented about the
F-theory dual of the bosonic string and tachyon condensation thereof.Comment: 16 pages, 2 figures, harvmac(b
