theorem Set.mem_uniontheorem Set.mem_union: ∀ {α : Type u} (x : α) (a b : Set α), x ∈ a ∪ b ↔ x ∈ a ∨ x ∈ b
Published by @sam · Jul 21, 2026
View source in zpg9xh52
zpg9xh52
Definitional, with no premises to accept.
Set.mem_union
definitional fact