Difference between revisions of "Metric space"

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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'') ≥ ...)
 
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The function ''d'' generalizes the notion of length from ordinary [[Euclidean space]].
 
The function ''d'' generalizes the notion of length from ordinary [[Euclidean space]].
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[[Category: Mathematics]]

Revision as of 19:05, March 20, 2007

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

  1. d(x, y) ≥ 0     (non-negativity)
  2. d(x, y) = 0   if and only if   x = y     (identity)
  3. d(x, y) = d(y, x)     (symmetry)
  4. d(x, z) ≤ d(x, y) + d(y, z)     (triangle inequality).

The function d generalizes the notion of length from ordinary Euclidean space.