NAND, also known as the Sheffer stroke, is a connective in logic equivalent to the composition NOT AND that yields true if any condition
is false, and false if all conditions
are true. 
NAND 
is equivalent to 
,
where 
denotes NOT
and 
denotes AND.
In propositional calculus, the term alternative denial is used to refer to the NAND
connective. Notations for NAND include 
and 
(Mendelson 1997, p. 26). The NAND operation is implemented as Nand[A,
B, ...]. The circuit diagram symbol for an NAND gate is illustrated above.
The binary NAND operator has the following truth table (Mendelson 1997, p. 27).
 |  |  |
| T | T | F |
| T | F | T |
| F | T | T |
| F | F | T |
The NAND operation is the basic logical operation performed by the solid-state transistors ("NAND gates") that underlie virtually all integrated circuits and modern computers. The first axiom system based on NAND was given by Henry Sheffer in 1913. In their landmark tome, Whitehead and Russell (1927) promoted NAND as the appropriate foundation for axiomatic logic.
The AND function 
can be written in terms of NANDs as
 |
