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Venn diagram

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Imagine you are sorting a large collection of objects into different groups. You might have one group for things that are red and another for things that are round. Some objects, like a red ball, fit into both groups at once. A Venn diagram is a special way to draw these groups using closed curves. These curves are often simple circles or ovals drawn on a flat surface.

Venn diagram of legs and flying
Venn diagram of legs and flying

By overlapping the circles, you create new zones that show how the groups connect. This helps us see the logical relationships between different sets of things.

Each zone in the diagram tells a specific story about the objects. The area inside a circle represents the members of that set. The area outside the circle represents things that are not in that set. When two circles overlap, that middle space is called the intersection. This intersection contains only the items that belong to both groups. For example, a parrot belongs in the intersection of "two-legged creatures" and "flying creatures."

Venn diagram gr la ru
Venn diagram gr la ru

You can also talk about the union, which is the combined area of both circles. This represents everything that belongs to at least one of the groups.

People have used similar ideas for a very long time. In the 1700s, the mathematician Leonhard Euler used diagrams to show relationships. These are known as Euler diagrams. While they look similar to Venn diagrams, they are slightly different. An Euler diagram only shows the relationships that actually exist. A Venn diagram is more complete because it shows every possible relationship, even if a group is empty.

The 11 logical relations between two sets
The 11 logical relations between two sets

John Venn helped make these diagrams famous in the 1880s. He published his ideas in a book called "Symbolic Logic" in 1881.

John Venn was a very important figure in the history of logic. He actually called his own version "Eulerian Circles" at first. He wanted to use these drawings as a teaching tool for students. Later, in 1918, Clarence Irving Lewis began using the name "Venn diagram." These diagrams are used in many modern fields today. Scientists use them in statistics, linguistics, and computer science. They even help people study the math of probability.

Venn-stainedglass-gonville-caius
Venn-stainedglass-gonville-caius

As you add more groups, the diagrams can become much more complex. Drawing three circles is easy, but drawing four or more is a hard job. John Venn created an elegant design using ellipses for four sets. Another person, Anthony William Fairbank Edwards, created "Edwards-Venn diagrams" using a sphere. These can look like cogwheels with many teeth when drawn on a flat surface.

Venn3tab
Venn3tab

Even in modern times, these diagrams appear in internet memes. They remain a wonderful way to turn tricky logic into a clear picture.

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🖼️ Images & Media (24)
File:Venn diagram gr la ru.svg
Venn diagram gr la ru.svg
File:Venn diagram of legs and flying.svg
Venn diagram of legs and flying.svg
File:Venn-stainedglass-gonville-caius.jpg
Venn-stainedglass-gonville-caius.jpg
File:4 spheres, cell 00, solid.png
4 spheres, cell 00, solid.png
File:4 spheres, weight 1, solid.png
4 spheres, weight 1, solid.png
File:4 spheres, cell 01, solid.png
4 spheres, cell 01, solid.png
File:4 spheres, cell 02, solid.png
4 spheres, cell 02, solid.png
File:4 spheres, cell 04, solid.png
4 spheres, cell 04, solid.png
File:4 spheres, cell 08, solid.png
4 spheres, cell 08, solid.png
File:4 spheres, weight 2, solid.png
4 spheres, weight 2, solid.png
File:4 spheres, cell 03, solid.png
4 spheres, cell 03, solid.png
File:4 spheres, cell 05, solid.png
4 spheres, cell 05, solid.png

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