Finite scale factor and future singularities
  The main characteristic of the dark energy is its negative pressure. In a
homogeneous and isotropic FRW background, we consider several models for the
dark energy fluid, which lead to finite time future singularities of the type
I-IV, by introducing the pressure density as a function of the scale factor.
This approach gives acceptable behavior of the dark energy equation of state.
We give various numerical examples of models with type I-IV singularities, that
show very similar late time behavior, making it difficult to determine the type
of singularity that would take place in the future.
