Difference between revisions of "Metric space"

From Conservapedia
Jump to navigation Jump to search
m (New page: A '''metric space''' is a pair (''X'', ''d'') where ''X'' is a topological space and ''d'' is a function mapping elements in ''M'' to real numbers, such that # ''d''(''x'', ''y'') ≥ ...)
 
(→‎top: clean up & uniformity)
 
(10 intermediate revisions by 5 users not shown)
Line 1: Line 1:
−
A '''metric space''' is a pair (''X'', ''d'') where ''X'' is a [[topological space]] and ''d'' is a function mapping elements in ''M'' to real numbers, such that
+
A '''metric space''' is a pair (''X'', ''d'') where ''X'' is a [[topological space]] and ''d'' is a [[Metric (mathematics)|metric]]. All metric spaces are [[Hausdorff space]]s.
−
# ''d''(''x'', ''y'') ≥ 0     (''non-negativity'')
 
−
# ''d''(''x'', ''y'') = 0   if and only if   ''x'' = ''y''     (''identity'')
 
−
# ''d''(''x'', ''y'') = ''d''(''y'', ''x'')      (''symmetry'')
 
−
# ''d''(''x'', ''z'') ≤ ''d''(''x'', ''y'') + ''d''(''y'', ''z'')     (''[[triangle inequality]]'').
 
  
−
The function ''d'' generalizes the notion of length from ordinary [[Euclidean space]].
+
Examples of metric spaces include:
 +
 
 +
*the set of [[real numbers]]
 +
*a [[Euclidean space]] of any dimension
 +
*any set of finite points where the distance between distinct points is defined as 1, and the distance between a point and itself is defined as zero.
 +
 
 +
[[Category:Mathematics]]
 +
[[Category:Topology]]

Latest revision as of 15:59, July 13, 2016

A metric space is a pair (X, d) where X is a topological space and d is a metric. All metric spaces are Hausdorff spaces.

Examples of metric spaces include:

  • the set of real numbers
  • a Euclidean space of any dimension
  • any set of finite points where the distance between distinct points is defined as 1, and the distance between a point and itself is defined as zero.