Certainty: whether an element belongs to a set is certain, that is, any object can clearly determine whether it is an element of this set, and the two must be one of them. This is the criterion to judge whether a group of objects constitute a set.
Reciprocity: The elements of a given set are different from each other, and the same element can only be counted as one in the set.
Disorder: A set has nothing to do with the order of its elements.
Set is an important basic concept in modern mathematics. The basic theory of set theory was not established until the end of 19. Now it has become a common part of mathematics education, and it has been studied since primary school. Here is a brief and basic introduction to what mathematicians call "intuitive" or "simple" set theory; A more detailed analysis shows the naive set theory. Axiomatic set theory can be seen through the strict axiomatic deduction of sets.
Set (or simple set) is a basic mathematical concept and the research object of set theory. In the simplest way, defined by the most primitive set theory-naive set theory, a set is "a bunch of things". The "things" in a set are called elements. If x is an element of set a, let it be x ∈ a.
To put it simply, the so-called set is to divide several objects into one or several whole sizes and shapes. Generally speaking, a set is a whole of things with certain characteristics, or a set of certain objects. The things or objects that make up a set are called elements or members. The elements of a set can be anything, people, things, letters or numbers.
In computer science, a set is a combination of a variable number of data items (or possibly zero), which may share some characteristics and need to be operated together in some way. Generally speaking, these data items are the same type or the same base class (if the language used supports inheritance). A list (or array) is usually not considered as a collection because its size is fixed, but in fact it is often used as some form of collection in implementation.
The types of sets include list, set, multiple sets, tree and graph. Enumeration types can be lists or collections.
In the list, the order of data items is determined, and there may be multiple identical data items. The operations supported by the list include finding an item and finding its location (if any), deleting an item from the list, inserting an item at a specific location, and so on. The usual queue, or FIFO, is just a linked list, and entries can only be added at one end and deleted at the other. Stack or LIFO can only add or delete items on the same side. Whether it is a queue or a stack, the order of items in a collection should be certain, so these two cases are only special cases of lists. Other operations supported by lists include sorting, which once again illustrates the importance of order.
The specific forms of lists include arrays and linked lists.