K-maps are constructed such that the logically adjacent terms are geometrically adjacent. For 4 Boolean variables w, x, y, and z, maxterms (w+x'+y+z) and (w+x'+y'+z') are logically adjacent.

In a 4-variable K-map, we can draw rectangles composed of 4 squares of value ​​1, the corresponding term is a product of 2 literals.

In a 4-variable K-map, each square has 4 adjacent squares

In a 3-variable K-map, two adjacent squares with values ​​1 represent a product of 2 literals.