A collection refers to a collection of concrete or abstract objects with certain attributes, which are called elements of a collection. A set can be represented by symbols, and the symbols and meanings in the set are as follows:

∪

and

∩

transmit

Answer? b，

A belongs to B.

Answer? b，

A includes B.

∈

A∈A, A is the element of A.

Answer? B, a is not greater than B.

Answer? B, a is not less than B.

Φ

null set

rare

real number

ordinary

natural number

Z

integer

Z+ positive integer

Z-

negative integer

Extended data:

Set related concepts

1, meaning of set: some specified objects are set together into a set, and each object is called an element.

2. Three characteristics of elements in a set:

Determinism of (1) element;

(2) mutual anisotropy of elements;

(3) the disorder of elements

Related knowledge:

1. For a given set, the elements in the set are certain, and any object is either an element of the given set or not.

2. In any given set, any two elements are different objects. When the same object is contained in a collection, it is only an element.

3. The elements in the set are equal, and there is no order. Therefore, to judge whether two sets are the same, it is only necessary to compare whether their elements are the same, and it is not necessary to check whether the arrangement order is the same.

Set classification:

1, finite set

A collection with a finite number of elements.

2. Infinite set

A collection containing an infinite number of elements.

3. Empty set

A collection that does not contain any elements.

Example: {x|x2=-5}

Representation of a set:

1, enumeration method: list the elements in the collection one by one, and then enclose them in braces.

2. Description: A method of describing the common attributes of elements in a collection and writing them in braces to represent the collection. A method to indicate whether some objects belong to this set under certain conditions.

Reference: Sogou Encyclopedia-Mathematics Highlights