AdaptaHOP (solid line) and FOF (dashed line) halo mass function for the four zoom level: level 3 in green, 2 in blue, 1 in red, and 0 in magenta. Note that subhaloes are not counted separately, but are included within the AdaptaHOP haloes in order to compare with FOF haloes. The black line is a Press & Schechter predicted mass function, for the sake of comparison, and characterisation of the environment.