How many less of the Dorchester population have completed some college than have a academic degree?
return Dorchester ;return population of #1 ;return #2 that has completed some college ;return #2 that has a academic degree ;return number of  #3 ;return number of  #4 ;return difference of #6 and  #5
['select', 'project', 'filter', 'filter', 'aggregate', 'aggregate', 'arithmetic']