  By incorporating the holographic principle in a time-depending Lambda-term
cosmology, new physical bounds on the arbitrary parameters of the model can be
obtained. Considering then the dark energy as a purely geometric entity, for
which no equation of state has to be introduced, it is shown that the resulting
range of allowed values for the parameters may explain both the coincidence
problem and the universe accelerated expansion, without resorting to any kind
of additional structures.
