case h
α : Type u_1
s : Set α
t : Set Bool
x : α
⊢ x ∈ boolIndicator s ⁻¹' t ↔ x ∈ (if true ∈ t then s else ∅) ∪ if false ∈ t then sᶜ else ∅
α : Type u_1
s : Set α
t : Set Bool
⊢ boolIndicator s ⁻¹' t = (if true ∈ t then s else ∅) ∪ if false ∈ t then sᶜ else ∅
ext x
case h
α : Type u_1
s : Set α
t : Set Bool
x : α
⊢ (if x ∈ s then true else false) ∈ t ↔ x ∈ (if true ∈ t then s else ∅) ∪ if false ∈ t then sᶜ else ∅
case h
α : Type u_1
s : Set α
t : Set Bool
x : α
⊢ x ∈ boolIndicator s ⁻¹' t ↔ x ∈ (if true ∈ t then s else ∅) ∪ if false ∈ t then sᶜ else ∅
simp only [boolIndicator, mem_preimage]
no goals
case h
α : Type u_1
s : Set α
t : Set Bool
x : α
⊢ (if x ∈ s then true else false) ∈ t ↔ x ∈ (if true ∈ t then s else ∅) ∪ if false ∈ t then sᶜ else ∅
split_ifs <;> simp [*]