3-input MAJ gate

Marnaugh Map (K-map) is a graphical tool that provides a simple and straightforward method of minimizing Boolean expressions. The K-map method was introduced in 1953 by Maurice Karnaugh as an enhancement to Veitch diagram.

Format

Map Formats

A K-map is a square or rectangle divided into a number of smaller squares called cells. Each cell on the K-Map corresponds directly to a line in a truth table. There are always cells in a K-Map where is the number of variables in the function. Below are the usual formats for 1-4 variable k-maps (larges k-maps are discussed later on).

1-Variable K-map	2-Variables K-map
3-Variables K-map	4-Variables K-map

Map Labeling

The coordinates of the cells in a K-map are the input value combinations from the truth table. There are a number of common ways to label a K-map. The two most common methods are numerically and by variables and their complements. There are advantages to both. Regardless of which way you choose, the coordinates of two adjacent cells differ by only one variable - i.e. only one 0 can switch to a 1 and vice versa between two adjacent cells. For example, consider a function with 2 variables, the order by which you list them would be . Note how 11 and 10 were switched so that only one value is different.

Numerically	Variables
1-Variable K-map
2-Variables K-map
3-Variables K-map
4-Variables K-map

Map Cell Numbering

Sometimes the individual cells are numbered in accordance with their minterm index. Strictly speaking this is unnecessary, but it may be useful in various situations when working with minterms and maxterms. Cell numbering are usually written in one of the cell corners.