Английская Википедия:Integer broom topology

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In general topology, a branch of mathematics, the integer broom topology is an example of a topology on the so-called integer broom space X.

Definition of the integer broom space

Файл:Integer Broom Plot FBN.gif

Шаблон:Center

The integer broom space X is a subset of the plane R². Assume that the plane is parametrised by polar coordinates. The integer broom contains the origin and the points Шаблон:Nowrap such that n is a non-negative integer and Шаблон:Nowrap}, where Z⁺ is the set of positive integers. The image on the right gives an illustration for Шаблон:Nowrap and Шаблон:Nowrap. Geometrically, the space consists of a collection of convergent sequences. For a fixed n, we have a sequence of points − lying on circle with centre (0, 0) and radius n − that converges to the point (n, 0).

Definition of the integer broom topology

We define the topology on X by means of a product topology. The integer broom space is given by the polar coordinates

<math>(n, \theta) \in \{ n \in \Z : n \ge 0 \} \times \{ \theta = 1/k : k \in \Z^{+} \} \, .</math>

Let us write Шаблон:Nowrap for simplicity. The integer broom topology on X is the product topology induced by giving U the right order topology, and V the subspace topology from R.

Properties

The integer broom space, together with the integer broom topology, is a compact topological space. It is a T₀ space, but it is neither a T₁ space nor a Hausdorff space. The space is path connected, while neither locally connected nor arc connected.

See also

• Comb space
• Infinite broom
• List of topologies