Parameters of the composite cluster luminosity functions computed in increasing bins of redshift (left panel) and richness (right panel). From top to bottom, the plots show the normalisation ϕ^*, the faint endslope α, and the characteristic magnitude . The vertical error bars indicate the 68% c.i., whereas the horizontal ones reflect the bin size. The blue (red) points indicate the results when the faint end slope is free (fixed). The shaded blue regions show the evolution models we constrained from Eq. (10) at fixed richness (λ_{0.5 Mpc} = 13, left panel) and redshift (z = 0.3, right panel). The dashed black line shows a fiducial model for the evolution of M*; the black circles indicate the model values at the median redshifts of the richness bins.