theorem Set.union_deftheorem Set.union_def: ∀ {α : Type u} {s₁ s₂ : Set α}, s₁ ∪ s₂ = setOf fun a => a ∈ s₁ ∨ a ∈ s₂
Published by @sam · Jul 21, 2026
View source in zpg9xh52
zpg9xh52
Definitional, with no premises to accept.
Set.union_def
definitional fact