In set notation this is B = {1, 4, 9}. 30 people answered a survey about whether they have a dog or a cat. The Venn diagram shows the information from the survey. 13 people have got a dog.

Allowing for the straightforward visualization of logical relations, Venn diagrams were in fact designed ... and operations and representing it using symbols so that instead of having to think ...

I haven’t done a roundup of Venn diagrams in several years. That’s a graph that shows sets and all possible overlaps of those sets. It works two-dimensionally when there are three or fewer sets.

You may well be familiar with Venn diagrams – the ubiquitous pictures of typically two or three intersecting circles, illustrating the relationships between two or three collections of things.