Distribution of the total number of well-classified galaxies, where I (magenta) equals the sum of I_disk (blue) and I_merger (green), at low- (upper panels) and at high-z (bottom panels) as a function of the total kinematic asymmetry K_tot in the unweighted (left) and weighted (right) planes when assuming that only the isolated disks are considered “true disks” and ongoing and post-coalescence mergers are considered “true mergers”. The red dashed lines represent the “optimal” frontiers, which give us the K_tot values for which the maximum index I is derived; the solid black line indicates the value derived according to Eq. (5), while the two dashed black lines represent the statistical frontiers ( MAD).