- This article is about logical nor. For the legendary eponymous king of Norway see Nór.
Logical nor (not or) or Webb-operation is a boolean logic operator which produces a result that is the inverse of logical or. That is, p nor q is only true when neither p nor q is true, and is false otherwise. A common means of writing p NOR q is 
, where the symbol + signifies OR and the line over the expression signifies not, the logical negation of that expression
The two-input logical NOR operator is commonly described by a truth table, describing the output state for all possible input combinations:
| A | B | A nor B
|
| F | F | T
|
| F | T | F
|
| T | F | F
|
| T | T | F
|
Nor has the interesting feature that all other logical operators can be expressed by various functions of nor.
| "not p" is equivalent to "p NOR p"
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| "p and q" is equivalent to "(p NOR p) NOR (q NOR q)"
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| "p or q" is equivalent to "(p NOR q) NOR (p NOR q)"
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| p implies q" is equivalent to "((p NOR q) NOR q) NOR ((p NOR q) NOR q)"
| 
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This is similar to the logical nand operator.
See also:
