1, n: non-negative integer set or natural number set {0, 1, 2,3, ...}

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

3, z: integer set {…,-1, 0, 1, …}

4. Q: Rational number set

5.Q+: Positive Rational Number Set

6.Q-: set of negative rational numbers

7.r: set of real numbers (including rational numbers and irrational numbers)

8.R+: positive real number set

9.R-: negative real number set

10, c: complex set

1 1、? : empty set (a set without any elements)

Extended data:

Set the basics:

1. Definition: Generally speaking, we call the research object an element, and the whole composed of some elements is called a set, which is also called a set for short;

2. Representation method: sets usually use braces {? } or uppercase Latin letters a, b, c…, while elements are represented by lowercase Latin letters a, b, C….

3. On the characteristics of set elements

(1) Determinism: Given a set, determine whether any element is in this set or not; ?

(2) Reciprocity: the elements in the set are different from each other, that is, the elements in the set do not appear repeatedly;

(3) Disorder: that is, the elements in the set are disordered and can be arranged and exchanged at will.

4. Relationship between elements and sets: (The relationship between elements and sets can be divided into "attribution" and "non-attribution")

(1) If A is an element in set A, it is said that A belongs to set A;

(2) If A is not an element of set A, it is said that A does not belong to set A. ..

5. Representation method of set

(1) enumeration: the method of enumerating the elements in a collection one by one and enclosing them in curly braces is called enumeration;

(2) Description: The method of representing a set with * * * identical features of elements contained in the set is called description;

(3) venn diagram method: Draw a closed curve and use its interior to represent a set.

References:

Baidu Encyclopedia: Collection