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point (Definition)

In The Elements, Euclid defines a point as that which has no part.

In a vector space, an affine space, or, more generally, an incidence geometry, a point is a zero dimensional object.

In a projective geometry, a point is a one-dimensional subspace of the vector space underlying the projective geometry.

In a topology, a point is an element of a topological space.

In function theory, a point usually means a complex number as an element of the complex plane.

Note that there is also the possibility for a point-free approach to geometry in which points are not assumed as a primitive. Instead, points are defined by suitable abstraction processes. (See point-free geometry.)




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"point" is owned by Wkbj79. [ full author list (4) ]
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Cross-references: point-free geometry, primitive, geometry, complex plane, complex number, function theory, element, topology, subspace, projective geometry, incidence geometry, affine space, vector space
There are 1389 references to this entry.

This is version 13 of point, born on 2006-07-24, modified 2010-07-14.
Object id is 8173, canonical name is Point.
Accessed 14465 times total.

Classification:
AMS MSC51-00 (Geometry :: General reference works )
 54-00 (General topology :: General reference works )
 15-00 (Linear and multilinear algebra; matrix theory :: General reference works )

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point by Wkbj79 on 2006-07-24 20:39:22
While reading Mathprof's entry "metacompact", I was surprised to notice that the word "point" had no link. I was curious enough to look at the TeX code and was surprised to find that he had not supressed a link.

After looking around on PM to be sure that "point" really was not an entry, I decided that it would be a good idea to have a definition of it. This is my humble and modest beginning. I am quite sure that the word "point" has many different definitions in many different areas of mathematics, and I would appreciate it if you would add them. Thanks.

Warren
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