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.

Our opening quote contended that Venn diagrams are overrated. Even those who agree must admit that they have a curious allure. Take the sets of interesting topics in logic, in geometry and in ...

Allowing for the straightforward visualization of logical relations, Venn diagrams were in fact designed ... and operations ...