CatDat

category of metric spaces with ∞ allowed

  • notation: Met\mathbf{Met}_{\infty}
  • objects: metric spaces, where the metric is allowed to assume the value \infty
  • 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 categories: Metc\mathbf{Met}_cMet\mathbf{Met}
  • nLab Link

The fact that we allow \infty means that universal constructions work much better when compared to Met\mathbf{Met}.

Satisfied Properties

Properties from the database

Deduced properties

Unsatisfied Properties

Properties from the database

Deduced properties*

*This also uses the deduced satisfied properties.

Unknown properties

There are 3 properties for which the database doesn't have an answer if they are satisfied or not. Please help to contribute the data!

Special objects

  • terminal object: singleton space
  • initial object: empty metric space
  • products: direct products with the metric d(x,y)=supidi(xi,yi)d(x,y) = \sup_i d_i(x_i,y_i)
  • coproducts: disjoint union with the metric that extends the given ones and gives points in different spaces the distance \infty

Special morphisms

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