  We analyze the phase space of a particular unified model of dark matter, dark
energy, and inflation that we recently studied in [Phys. Rev. D 83, 063502
(2011)] whose Lagrangian is of the form L(X,phi) = F(X) - V(phi). We show that
this model possesses a large set of initial conditions consistent with a
successful cosmological model in which an inflationary phase is possible,
followed by a matter era to end with dark energy domination. In order to
understand the success of the model, we study the general features that unified
dark matter (UDM) models should comply and then we analyze some particular
models and find their constrictions.
