LeanPool.AFormalizationOfBorelDeterminacyInLean.Basic.General #
Auxiliary declarations for the Borel determinacy formalization.
theorem
Set.hEq_of_image_eq
{α : Type u_6}
{A A' : Set α}
(h : A = A')
{B : Set ↑A}
{B' : Set ↑A'}
(h' : Subtype.val '' B = Subtype.val '' B')
:
theorem
Cardinal.choose_injection
{α β : Type u}
(f : α → Set β)
(h : ∀ (a : α), mk α ≤ mk ↑(f a))
:
∃ (g : α → β), Function.Injective g ∧ ∀ (a : α), g a ∈ f a