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The null sign (∅) is often used in mathematics for denoting the empty set. The same letter in linguistics represents zero , the lack of an element. It is commonly used in phonology , morphology , and syntax .
In mathematics, the empty set or void set is the unique set having no elements; its size or cardinality (count of elements in a set) is zero. [1] Some axiomatic set theories ensure that the empty set exists by including an axiom of empty set , while in other theories, its existence can be deduced.
In mathematics, the word null (from German: null [citation needed] meaning "zero", which is from Latin: nullus meaning "none") is often associated with the concept of zero or the concept of nothing. [ 1 ] [ 2 ] It is used in varying context from "having zero members in a set " (e.g., null set) [ 3 ] to "having a value of zero " (e.g., null vector).
Null symbol may refer to: Null character , U+0000 <control-0000> , U+2400 ␀ SYMBOL FOR NULL (a single-character glyph "NUL") Null sign (∅), the empty set
Null sets play a key role in the definition of the Lebesgue integral: if functions and are equal except on a null set, then is integrable if and only if is, and their integrals are equal. This motivates the formal definition of L p {\displaystyle L^{p}} spaces as sets of equivalence classes of functions which differ only on null sets.
They were introduced by the mathematician Georg Cantor [1] and are named after the symbol he used to denote them, the Hebrew letter aleph (ℵ). [2] [a] The cardinality of the natural numbers is ℵ 0 (read aleph-nought, aleph-zero, or aleph-null), the next larger cardinality of a well-ordered set is aleph-one ℵ 1, then ℵ 2 and so on.
The number 0 is represented by zero while null is a representation of an empty set {}. Hence in computer science a zero represents the outcome of a mathematical computation such as 2−2, while null is used for an undefined state (for example, a memory location that has not been explicitly initialised).
The presence of null values leads to three-valued logic. No longer is a condition either true or false, but it can be undetermined. Any computation including a null value delivers a null result. [92] In mathematics, there is no "positive zero" or "negative zero" distinct from zero; both −0 and +0 represent exactly the same number.