modern use, the Venn diagram includes a "box" that surrounds all the circles; this is called the universe of discourse or the domain of discourse.

Couturat observed that, in a direct algorithmic (formal, systematic) manner, one cannot derive reduced Boolean equations, nor does it show how to arrive at the conclusion " is ". Couturat concluded that the process "has ... serious inconveniences as a method for solving logical problems":
:"It does not show