mathlib3 documentation


Any T0 space embeds in a product of copies of the Sierpinski space. #

THIS FILE IS SYNCHRONIZED WITH MATHLIB4. Any changes to this file require a corresponding PR to mathlib4.

We consider Prop with the Sierpinski topology. If X is a topological space, there is a continuous map product_of_mem_opens from X to opens X → Prop which is the product of the maps X → Prop given by x ↦ x ∈ u.

The map product_of_mem_opens is always inducing. Whenever X is T0, product_of_mem_opens is also injective and therefore an embedding.

The continuous map from X to the product of copies of the Sierpinski space, (one copy for each open subset u of X). The u coordinate of product_of_mem_opens x is given by x ∈ u.