Z: integer set {…,-1, 0, 1, …}

Q: Rational number set

R: set of real numbers (including rational numbers and irrational numbers)

Others:

R+: positive real number set

R-: negative real number set

C: complex set

: empty set (a set without any elements)

N* or N+: positive integer set {1, 2,3, …}

Q+: Set of Positive Rational Numbers

Q-: set of negative rational numbers

Extended data:

Set, for short, is a basic concept in mathematics and the main research object of set theory. The basic theory of set theory was founded in19th century. The simplest statement about set is the definition in naive set theory (the most primitive set theory), that is, set is "a certain pile of things" and the "things" in set are called elements. A modern set is usually defined as a whole consisting of one or more definite elements.

Set concept:

A collection refers to a collection of concrete or abstract objects with certain attributes. Among them, these objects that make up the set are called elements of the set.

For example, the collection of all China people, its element is every China person. Generally, uppercase letters such as A, B, S, T, ... are used to represent a set, while lowercase letters such as A, B, X, Y, ... are used to represent elements in the set. If X is an element of the set S, it is said that X belongs to S and is marked as X ∈ S ... If Y is not an element of the set S, it is said that Y does not belong to S and is marked as Y? s？ [2]。

References:

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