Module

Pullbacks.lean

Nyll.ProCGroups.ProC.Category.Pullbacks
2 declarations indexed from sourceView source ↗

Pro C Groups / pro-C / Category / Pullbacks

This module relates mathlib's CategoryTheory.IsPullback predicate in ProCGrp C to the concrete universal property tested against profinite source groups.

Imports3
Imported by1

Declarations

ProCGrp.isPullback_of_hasProfiniteTestPullbackProperty

A continuous profinite-test pullback square is a pullback in ProCGrp.

Source context 7 commands

Surrounding namespaces, section variables, and local commands at this declaration.

open CategoryTheory
open CategoryTheory.Limits
open ProCGroups.Categorical
universe u
namespace ProCGrp
variable {ProC : ProCGroups.FiniteGroupClass.{u}}
variable {G H H1 H2 : ProCGrp ProC}
theorem isPullback_of_hasProfiniteTestPullbackProperty
    {alpha1 : G ⟶ H1} {alpha2 : G ⟶ H2}
    {beta1 : H1 ⟶ H} {beta2 : H2 ⟶ H}
    (hpb : HasProfiniteTestPullbackProperty
      (continuousHom alpha1) (continuousHom alpha2)
      (continuousHom beta1) (continuousHom beta2)) :
    CategoryTheory.IsPullback alpha1 alpha2 beta1 beta2
ProCGrp.hasProfiniteTestPullbackProperty_of_isPullback_allFinite

In the all-finite category, a pullback has the profinite-test universal property.

Source context 7 commands

Surrounding namespaces, section variables, and local commands at this declaration.

open CategoryTheory
open CategoryTheory.Limits
open ProCGroups.Categorical
universe u
namespace ProCGrp
variable {ProC : ProCGroups.FiniteGroupClass.{u}}
variable {G H H1 H2 : ProCGrp ProC}
theorem hasProfiniteTestPullbackProperty_of_isPullback_allFinite
    {G H H1 H2 : ProCGrp ProCGroups.FiniteGroupClass.allFinite}
    {alpha1 : G ⟶ H1} {alpha2 : G ⟶ H2}
    {beta1 : H1 ⟶ H} {beta2 : H2 ⟶ H}
    (hpb : CategoryTheory.IsPullback alpha1 alpha2 beta1 beta2) :
    HasProfiniteTestPullbackProperty
      (continuousHom alpha1) (continuousHom alpha2)
      (continuousHom beta1) (continuousHom beta2)