Uniformly continuous map: Difference between revisions

Latest revision as of 23:07, 24 November 2008

Definition

Between uniform spaces

Suppose $(X, U)$ and $(Y, V)$ are uniform spaces (in other words, $X$ and $Y$ are sets and $U$ and $V$ are uniform structures on $X$ and $Y$ respectively). A function $f : X \to Y$ is termed a uniformly continuous map if the following holds: For any $V \in V$ (i.e., for every entourage of $Y$ ) there exists a $U \in U$ such that $(a, b) \in U ⟹ (f (a), f (b)) \in V$ .

Between metric spaces

Further information: Uniformly continuous map of metric spaces Suppose $(X, d_{X})$ and $(Y, d_{Y})$ are metric spaces (in other words, $X$ and $Y$ are sets and $d_{X}$ and $d_{Y}$ are metrics on $X$ and $Y$ respectively). A function $f : X \to Y$ is termed a uniformly continuous map if the following holds:

$\forall ε > 0 \exists δ > 0 : d_{X} (a, b) < δ ⟹ d_{Y} (f (a), f (b)) < ε$ .

@@ Line 7: / Line 7: @@
 ===Between metric spaces===
+{{further|[[Uniformly continuous map of metric spaces]]}}
 Suppose <math>(X,d_X)</math> and <math>(Y,d_Y)</math> are [[metric space]]s (in other words, <math>X</math> and <math>Y</math> are sets and <math>d_X</math> and <math>d_Y</math> are metrics on <math>X</math> and <math>Y</math> respectively). A function <math>f:X \to Y</math> is termed a '''uniformly continuous map''' if the following holds:
-<math>\forall \ \varepsilon > 0 \ \exists \delta > 0 : \left| d_X(a,b) \right| < \delta \implies \left| d_Y(f(a),f(b)) \right| < \varepsilon</math>.
+<math>\forall \ \varepsilon > 0 \ \exists \delta > 0 : d_X(a,b) < \delta \implies d_Y(f(a),f(b)) < \varepsilon</math>.