# What is null set?

see null set means no elements in the set ,than set= set of elements ,so my question is ,no elements in the set how it becom null set?

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As the name suggests, null means empty, a set which does not have any element.

e.g. set of white crows, set of vehicles having square wheels,
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A set means a collection of elements by definition. If a set can be defined but has no elements in it then it is a null set.

Example: Set of objects traveling faster than light.
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Ur question is very good,...

But as u told Null set is a set that has no elements...

Basically null means no value...

Therefore a NULL set is called a set that has no elements in it...

Am I properly answered to ur question?
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It frustrates me when I see people talk of 'A null set' or 'An empty set'. One of the axioms of set theory is that two sets are equal if they contain the same elements. Since all null sets and empty sets contain the same elements [IE none at all] they are the same, so we refer to is as THE null set or THE empty set.

One way to think of the empty set is just through cardinality. The empty set has cardinality zero, no elements. Inset notation it's written { }. Nada, nothing. It's a subset of every single set.

In my philosophy, the empty set is the foundation of all mathematics. One is the cardinality of the set which contains the empty set, IE |{ {} }|=1

You just build up from nothing.
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You are right when you say that set is a set of elements... but then what if element=null? the analogy is an imaginary number.

We know in nature imaginary numbers cannot exist but it still is there - its there to handle exceptions that mathematical equations generate.

Like that in set theory ( and its real-life applications ) many a time, you encounter sets that have no elements in them but they do exist... they are called sets.

A foremost example of a null set would be bodies at 0kelvin temperature. They can't exist but as exceptions, you cannot negate them either ...