  A three-dimensional semiclassical model is used to study double ionization of
Ar when driven by a near-infrared and near-single-cycle laser pulse for
intensities ranging from 0.85$\times$10$^{14}$ W/cm$^{2}$ to 5$\times$10$^{14}$
W/cm$^{2}$. Asymmetry parameters, distributions of the sum of the two electron
momentum components along the direction of the polarization of the laser field
and correlated momenta are computed as a function of intensity and of the
carrier envelope phase. A very good agreement is found with recently obtained
results in kinematically complete experiments employing near-single-cycle laser
pulses. Moreover, the contribution of the direct and delayed pathways of double
ionization is investigated for the above observables. Finally, an
experimentally obtained anti-correlation momentum pattern at higher intensities
is reproduced with the three-dimensional semiclassical model and shown to be
due to a transition from strong to soft recollisions with increasing intensity.
