Venn diagram: Also called Venn diagram, it is used to show the overlapping areas of element sets. The history of venn diagram, 1880, venn diagram first used the positioning cross ring form and shadow to represent logical problems in the article "On the Graphical and Mechanized Representation of Propositions and Reasoning" (as shown in figure 1), which not only excited logicians-so much so that many logicians devoted themselves to it in the late19th century and throughout the 20th century until today. Venn diagram occupies a very important position in a large number of logical works, and venn diagram has also been applied to mathematics, especially set theory.