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Karnaugh map

math Maturity 11-13 Next article →

Computers and digital machines use logic to make decisions.

Karnaugh
Karnaugh

This logic is often written as long math expressions. These expressions can become very hard to read. They can also be hard for a machine to run. A Karnaugh map is a special tool used to simplify these rules. It helps engineers find the shortest way to build a circuit. This means they use fewer parts to get the same job done.

K-map minterms A
K-map minterms A

Using these maps saves a lot of time and effort.

To use the map, you start with a truth table. A truth table lists every possible input and the result. You move these results onto a two-dimensional grid.

K-map 6,8,9,10,11,12,13,14
K-map 6,8,9,10,11,12,13,14

The grid is special because it uses Gray code. In Gray code, only one value changes between neighbors. This helps the human eye spot patterns very quickly. You look for groups of 1s or groups of 0s. These groups must be rectangles or squares. Each group must also have an area that is a power of two. This includes sizes like one, two, four, or eight cells.

People have been working on these ideas for a long time.

karnaugh map torus
karnaugh map torus

In 1881, Allan Marquand made a logical diagram. Later, in 1952, Edward W. Veitch made the Veitch chart. Maurice Karnaugh improved this idea in 1953. Because of this history, some people call them Marquand–Veitch diagrams. They are also known as Karnaugh–Veitch maps. These tools were a big step forward for formal logic. They helped move math into the digital age we live in today.

The map has some very interesting rules about its shape.

Torus from rectangle
Torus from rectangle

You can think of the grid as a torus. A torus is a shape like a donut. This means the map wraps around its edges. The top edge touches the bottom edge. The far left edge also touches the far right edge. This allows you to make groups that wrap around the corners. You can even use "don't care" conditions to help. A "don't care" is a result that does not matter. You can use them to make your groups even larger.

Engineers also use these maps to find race hazards.

K-map 6,8,9,10,11,12,13,14 anti-race
K-map 6,8,9,10,11,12,13,14 anti-race

A race hazard is a tiny, unwanted glitch. It happens when a circuit moves between two different states. These glitches can cause mistakes in a machine. By looking at the map, you can see where these gaps exist. You can then add extra terms to bridge the gaps. This makes the machine work smoothly without any errors. It is a clever way to make technology more reliable.

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🖼️ Images & Media (7)
File:Karnaugh.svg
Karnaugh.svg
File:karnaugh_map_torus.svg
karnaugh_map_torus.svg
File:K-map minterms A.svg
K-map minterms A.svg
File:Torus from rectangle.gif
Torus from rectangle.gif
File:K-map 6,8,9,10,11,12,13,14.svg
K-map 6,8,9,10,11,12,13,14.svg
File:K-map 6,8,9,10,11,12,13,14 don't care.svg
K-map 6,8,9,10,11,12,13,14 don't care.svg
File:K-map 6,8,9,10,11,12,13,14 anti-race.svg
K-map 6,8,9,10,11,12,13,14 anti-race.svg
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