Cosmological evolution in exponential gravity
  We explore the cosmological evolution in the exponential gravity $f(R)=R +c_1
(1-e^{- c_2 R})$ ($c_{1, 2} = \mathrm{constant}$). We summarize various
viability conditions and explicitly demonstrate that the late-time cosmic
acceleration following the matter-dominated stage can be realized. We also
study the equation of state for dark energy and confirm that the crossing of
the phantom divide from the phantom phase to the non-phantom (quintessence) one
can occur. Furthermore, we illustrate that the cosmological horizon entropy
globally increases with time.
