How to build compact cells?
Therefore: first create a local density and split on its value (Csabai etal 96)
The SDSS will measure fluxes in 5 bands => asinh magnitudes
Axis-parallel splits in median flux, in 8 separate zones in Galactic latitude => 5 dimensional bounding boxes
The fluxes are strongly correlated => 2 +? dimensional distribution of typical objects => widely scattered rare objects => large density contrasts