Binary operation that is true if and only if both operands are false
This article is about NOR in the logical sense. For the electronic gate, see NOR gate. For other uses, see Nor.
"Peirce arrow" redirects here. Not to be confused with Pierce-Arrow, an automobile manufacturer.
"Webb operation" redirects here. Not to be confused with Web operations.
Logical NOR
NOR
Definition
Truth table
Logic gate
Normal forms
Disjunctive
Conjunctive
Zhegalkin polynomial
Post's lattices
0-preserving
no
1-preserving
no
Monotone
no
Affine
no
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e
Logical connectives
AND
, , , ,
equivalent
, ,
implies
, ,
NAND
, , ,
nonequivalent
, ,
NOR
, ,
NOT
, , ,
OR
, , ,
XNOR
XOR
,
converse
, ,
Related concepts
Propositional calculus
Predicate logic
Boolean algebra
Truth table
Truth function
Boolean function
Functional completeness
Applications
Digital logic
Programming languages
Mathematical logic
Philosophy of logic
Category
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In Boolean logic, logical NOR,[1]non-disjunction, or joint denial[1] is a truth-functional operator which produces a result that is the negation of logical or. That is, a sentence of the form (p NOR q) is true precisely when neither p nor q is true—i.e. when both p and q are false. It is logically equivalent to and , where the symbol signifies logical negation, signifies OR, and signifies AND.
Non-disjunction is usually denoted as or or (prefix) or .
As with its dual, the NAND operator (also known as the Sheffer stroke—symbolized as either , or ), NOR can be used by itself, without any other logical operator, to constitute a logical formal system (making NOR functionally complete).
The computer used in the spacecraft that first carried humans to the moon, the Apollo Guidance Computer, was constructed entirely using NOR gates with three inputs.[2]
^ abHowson, Colin (1997). Logic with trees: an introduction to symbolic logic. London ; New York: Routledge. p. 43. ISBN 978-0-415-13342-5.
^Cite error: The named reference Hall_1996 was invoked but never defined (see the help page).
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