# Commit 2024-09-03 09:13 79c4b69e

View on Github →feat(Topology/CompHaus): sigma-comparison map (#15525)
This PR defines the map `CompHausLike.sigmaComparison`

associated to a presheaf `X`

on
`CompHausLike P`

, and a finite family `S₁,...,Sₙ`

of spaces in `CompHausLike P`

, where `P`

is
stable under taking finite disjoint unions.
The map `sigmaComparison`

is the canonical map `X(S₁ ⊔ ... ⊔ Sₙ) ⟶ X(S₁) × ... × X(Sₙ)`

induced by
the inclusion maps `Sᵢ ⟶ S₁ ⊔ ... ⊔ Sₙ`

, and it is an isomorphism when `X`

preserves finite
products.