Covariant Generalized Holographic Dark Energy and Accelerating Universe
  We proposed the generalized holographic dark energy model where infrared
cutoff is identified with the combination of the FRW universe parameters: the
Hubble rate, particle and future horizons, cosmological constant, the universe
life-time (if finite) and their derivatives. It is demonstrated that with the
corresponding choice of the cutoff one can map such holographic dark energy to
modified gravity or gravity with general fluid. Explicitly, F(R) gravity and
general perfect fluid are worked out in detail and corresponding infrared
cutoff is found. Using this correspondence, we get realistic inflation or
viable dark energy or unified inflationary-dark energy universe in terms of
covariant holographic dark energy.
