1 and venn diagram are used to express the mathematical or logical relationship between different groups of things (sets), especially the "approximate relationship" between sets (or classes), and are often used to help deduce (or understand) some laws about set operations (or class operations).

2. John vane was an English philosopher and mathematician in the19th century. He invented venn diagram in 188 1 year. There is a monument to his invention on the stained glass window of Caius College of Cambridge University.