T1 space

In topology and related branches of mathematics, a T₁ space is a topological space in which, for every pair of distinct points, each has a neighborhood not containing the other. An R₀ space is one in which this holds for every pair of topologically distinguishable points. The properties T₁ and R₀ are examples of separation axioms.

Definitions

Let X be a topological space and let x and y be points in X. We say that x and y can be separated if each lies in a neighborhood which does not contain the other point.

A T₁ space is also called an accessible space or a Fréchet space and a R₀ space is also called a symmetric space. (The term Fréchet space also has an entirely different meaning in functional analysis. For this reason, the term T₁ space is preferred. There is also a notion of a Fréchet-Urysohn space as a type of sequential space. The term symmetric space has another meaning.)

Space

Space is the boundless three-dimensional extent in which objects and events have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.

Glossary of chess

This page explains commonly used terms in chess in alphabetical order. Some of these have their own pages, like fork and pin. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific to chess problems, see Glossary of chess problems; for a list of chess-related games, see Chess variants.

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[adjective: prophylactic] Prophylactic techniques include the blockade, overprotection, and the mysterious rook move.

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References

Bibliography

Space (The Arrogant Worms album)

Space, stylized as SPACE, is the fourteenth album by the Canadian comedy music group, The Arrogant Worms. It was released in March 2014.

Track listing