Theories of the initial mass function
  We review the various theories which have been proposed along the years to
explain the origin of the stellar initial mass function. We pay particular
attention to four models, namely the competitive accretion and the theories
based respectively on stopped accretion, MHD shocks and turbulent dispersion.
In each case, we derive the main assumptions and calculations that support each
theory and stress their respective successes and failures or difficulties.
