English
If P.IsStableUnderBaseChange, then P.precoverage.HasIsos holds; i.e., pullbacks of covered arrows are isomorphisms when P satisfies the pullback criterion.
Русский
Если P.IsStableUnderBaseChange, то у P.precoverage возникают изоморфизмы для тяг в осн. изменение.
LaTeX
$$instance [P.IsStableUnderBaseChange] : P.precoverage.HasIsos$$
Lean4
instance [P.IsStableUnderBaseChange] : P.precoverage.IsStableUnderBaseChange where
mem_coverings_of_isPullback {ι} S X f hf T g W p₁ p₂ h Z g
hg := by
obtain ⟨i⟩ := hg
exact P.of_isPullback (h i).flip (hf ⟨i⟩)
