Not AND.
The Boolean function which is true unless both its arguments are true, the logical complement of AND :
A NAND B = NOT (A AND B) = (NOT A) OR (NOT B)
Its truth table is:
A | B | A NAND B --+---+--------- F | F | T F | T | T T | F | T T | T | F
NAND, like NOR , forms a complete set of Boolean functions on its own since it can be used to make NOT, AND, OR and any other Boolean function:
NOT A = A NAND A
A AND B = NOT (A NAND B)
A OR B = (NOT A) NAND (NOT B)
(1995-01-24)