(a) Collapse time as a function of the initial conditions for overdense perturbations with ﹩\delta _{0}=1﹩. The contours of constant collapse time, expressed by the scale factor a_c, are displayed for the ZA. The thin (thick) contours are spaced by 0.1 (0.5) in a_c, with the outermost contour being ﹩a_{c}=0.4﹩ and the central value ﹩a_{c}=3﹩. (b) Same as (a) except that the MZA is used. The innermost contour is ﹩a_{c}=1.6﹩. (c) Same as (a) except that the DTA is used. The innermost contour is ﹩a_{c}=1.6﹩. (d) Same as (a) except that the CZA is used. The innermost contour is ﹩a_{c}=1.7﹩. (e) Same as (a) except that the LTA is used. The innermost contour is ﹩a_{c}=1.6﹩. (f) Signs of ﹩\lambda ^{0}_{i}﹩ in each region of the parameter space of initial conditions, with ﹩\delta _{0}=1﹩. The inner region corresponds to the values of ﹩\lambda ^{0}_{i}﹩ that can be spanned by a homogeneous ellipsoid with any axis ratios. Spherical, planar, and cylindrically symmetric perturbations are marked with a cross, a plus sign, and an asterisk, respectively. The upper parts of these graphs, which correspond to ﹩0\leq \alpha _{0}\leq \pi ﹩, have ﹩\lambda ^{0}_{3}> \lambda ^{0}_{2}> \lambda ^{0}_{1}﹩. The lower one covers the same values of ﹩\lambda ^{0}_{i}﹩, through a permutation of the indices.