→ Mathematics This arrow represents the mapping. In mathematics, mapping is a term that refers to the "corresponding" relationship between two groups of elements, and it is a noun. In mathematics and related fields, mapping or projection is usually equivalent to a function.

Mapping has many names in different fields, and its essence is the same. Such as functions, operators and so on. What needs to be explained here is that a function is a mapping between two data sets, and other mappings are not functions. One-to-one mapping (bijection) is a special mapping, that is, the only correspondence between two groups of elements, usually one-to-one (one-to-one).

classify

Different mapping classification is based on the mapping results, from the following three angles:

1, classified according to the geometric properties of the results: surjective (upper) and non-surjective (inner).

2. According to the analytical nature of the results, they are classified as injective (one by one) and non-injective.

3. Consider the geometric and analytical properties: complete injection capacity (one-to-one correspondence).

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