Theorem: LO.FirstOrder.Arith.Model.domain_singleton (Arithmetization/ISigmaOne/HFS/Basic.lean)

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x y : M
⊢ ∀ (i : M), i ∈ domain {⟪x, y⟫} ↔ i ∈ {x}
Tactic:
simp [mem_domain_iff]
State after:
no goals