category of metric spaces with non-expansive maps

Notation Met\Met Objects metric spaces Morphisms non-expansive maps ff, meaning d(f(x),f(y))d(x,y)d(f(x),f(y)) \leq d(x,y) for all x,yx,y Related Ban\BanMetc\Met_cMet\Met_{\infty}PMet\PMet External nLab Link

In contrast to continuous maps, which only refer to the induced topology, non-expansive maps are closer related to the metrics themselves. This category is badly-behaved, though, especially when compared with Met\Met_{\infty}.

Satisfied Properties

Assigned properties

Deduced properties

Unsatisfied Properties

Assigned properties

Deduced properties*

*This also uses the deduced satisfied properties.

Unknown properties

There is 1 property for which the database doesn't have an answer if it is satisfied or not. Please help to contribute the data!

Special objects

  • terminal object: singleton space
  • initial object: empty metric space
  • products: [finite case] direct products with the metric d(x,y)=supidi(xi,yi)d(x,y) = \sup_i d_i(x_i,y_i)

Special morphisms

  • isomorphisms: bijective isometries
  • monomorphisms: injective non-expansive maps
  • epimorphisms: non-expansive maps with dense image
  • regular monomorphisms:
  • regular epimorphisms: