Many textbooks name K-map groups by size:
- a pair is 2 adjacent cells and removes 1 variable
- a quad is 4 cells, a row, column or 2×2 square, and removes 2 variables
- an octet is 8 cells, two rows or two columns, and removes 3 variables
In an n-variable map, the term from each has n − 1, n − 2 or n − 3 literals. In a 4-variable map that means 3, 2 or 1 literal.
The names are handy when comparing options: "this 1 can join a pair or a quad" tells you at once that the quad gives the shorter term. The underlying rule is the k map group size rule: every doubling removes one more variable.
A quad or octet can be split across an edge by the wrap. The four corners of a 4-variable map are a quad, for example.
A single isolated cell is sometimes called a single or a monomial group; it removes nothing. A group of 16 covers the whole map and gives the constant 1.
| AB\CD | 00 | 01 | 11 | 10 |
|---|---|---|---|---|
| 00 | 1m0 | 1m1 | 1m3 | 1m2 |
| 01 | 1m4 | 1m5 | 1m7 | 1m6 |
| 11 | 0m12 | 1m13 | 1m15 | 0m14 |
| 10 | 0m8 | 0m9 | 0m11 | 1m10 |