Karnaugh Map
The Karnaugh map can be used to find terms to combine for Boolean functions involving 2, 3 or 4 variables.
The 2-variable map is mostly useful for introducing the concept. When a Boolean function is written a sum-of-products, the map can simplify it graphically. In these examples
$$\begin{aligned}
&\text{(a) }xy+x̄y=(x+x̄)y=y \
&\text{(b) }xȳ+x̄y \
&\text{(c) }xȳ+x̄y+x̄ȳ=x̄ȳ
\end{aligned}$$
The 3-variable map is a 2x4 grid that wraps around horizontally.
The 4-variable map is a 4x4 grid that wraps around horizontally and vertically.
