The relationship between elements and sets is 1. All the specified objects form a set, usually represented by uppercase English letters, and each object is called an element, usually represented by lowercase English letters.
2. Three elements of set elements: certainty, mutual difference and disorder.
3. The relationship between sets and elements
(1) If A is an element in the set A, it is said that A belongs to A;
(2) If A is not an element in the set A, it is said that A does not belong to A;
Characteristics 1 of elements in a set, certainty For a given set, the elements in the set are certain, and any object is either an element of this 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 an unordered set are equal and have no order. So to judge whether two sets are the same, we only need to compare whether their elements are the same, and we don't need to examine whether the arrangement order is the same.
4. The three characteristics of logical set make the set itself deterministic and holistic.
5. All elements whose completeness meets the requirements are in the set.
6. All elements in the purity group meet the requirements.