F(A,B,C,D,E) = Σm(0,2,4,6,9,13,21,23,25,29,31) — Karnaugh map

exam standard5 variables drawn as two 4-variable planes

Answer

A′ · B′ · E′ + B · D′ · E + A · C · E

Why this example is worth doing

Five variables, drawn as two stacked 4-variable maps rather than one 4×8 strip. That choice is forced, not cosmetic: on a 3-bit Gray-coded axis six of the twenty-seven subcubes are non-contiguous, so a single wide map would draw groups that are not legal cubes and reject groups that are. With two planes, adjacency means the same cell position in the other plane, and the tool renders a cross-plane group as linked rectangles in both. Six variables extend the same idea to four planes.

Try your own input in the Karnaugh map solver. Group a 2- to 6-variable map yourself and have every group marked right or wrong.

How the answer is reached

Quine–McCluskey

Prime implicants — Quine–McCluskey
#Term
1A′ · B′ · E′
2B · D′ · E
3A · C · E
Minimum cover — Quine–McCluskey
#Cover
1A′ · B′ · E′ + B · D′ · E + A · C · E
Warning:

3 term(s), 9 literal(s); 3 essential prime implicant(s).

Truth table

Truth table — columns #, A, B, C, D, E, F
#ABCDEF
0000001
1000010
2000101
3000110
4001001
5001010
6001101
7001110
8010000
9010011
10010100
11010110
12011000
13011011
14011100
15011110
16100000
17100010
18100100
19100110
20101000
21101011
22101100
23101111
24110000
25110011
26110100
27110110
28111000
29111011
30111100
31111111

Compare with

Open this example in the Karnaugh map solver

The field arrives filled in with this example’s input.

Note:

Notation this page assumes

  • Symbols: · is AND, + is OR, ⊕ is XOR, a prime or an overline is NOT. The field also takes ∧ ∨ ¬ ~ ! & | and the words.
  • Operator precedence, tightest first: NOT, then AND (including juxtaposition), then XOR/XNOR, then NAND/NOR, then OR, then IMPLIES, then IFF.
  • In a minterm index the first variable is the most significant bit, so over [A, B, C] minterm 5 is A·B̄·C.

Sources

  • Karnaugh, “The Map Method for Synthesis of Combinational Logic Circuits” (1953)
  • Veitch, “A Chart Method for Simplifying Truth Functions” (1952)