# Space

<https://en.wikipedia.org/wiki/Space_(mathematics>)

A **space** is a set (sometimes a *universe*) with some added *mathematical structure*. Modern mathematics uses many types of spaces, but the term "space", per se, is a *mathematical primitive*.

A space consists of selected *mathematical objects* that are treated as *points*, and selected relationships between these points. The nature of the points can vary widely, for example, the points can be elements of a set, functions on another space or subspaces of another space. It is the relationships that define the nature of the space. More precisely, *isomorphic spaces* are considered identical, where an *isomorphism* between two spaces is a one-to-one correspondence between their points that preserves the relationships. For example, the relationships between the points of a 3D *Euclidean space* are uniquely determined by Euclid's axioms, and all 3D Euclidean spaces are considered identical.

The nature of the points can vary widely, the points can be

* elements of a set
* functions on another space
* subspaces of another space
* etc.

It is the relationships that define the nature of the space.

More precisely, *isomorphic spaces* are considered identical, where an isomorphism between two spaces is a one-to-one correspondence between their points that preserves the relationships. For example, the relationships between the points of a three-dimensional Euclidean space are uniquely determined by Euclid's axioms,\[details 2] and all three-dimensional Euclidean spaces are considered identical.

Topological notions such as continuity have natural definitions in every Euclidean space. However, topology does not distinguish straight lines from curved lines, and the relation between Euclidean and topological spaces is thus "forgetful". Relations of this kind are treated in more detail in the Section "Types of spaces".

It is not always clear whether a given mathematical object should be considered as a geometric "space", or an algebraic "structure". A general definition of "structure", proposed by Bourbaki, embraces all common types of spaces, provides a general definition of isomorphism, and justifies the transfer of properties between isomorphic structures.

Modern mathematics uses many types of spaces:

* Euclidean spaces
* linear spaces
* topological spaces
* Hilbert spaces
* probability spaces
