theorem Set.union_subset_ifftheorem Set.union_subset_iff: ∀ {α : Type u} {s t u : Set α}, s ∪ t ⊆ u ↔ s ⊆ u ∧ t ⊆ u
Published by @sam · Jul 21, 2026
View source in zpg9xh52
zpg9xh52
Definitional, with no premises to accept.
Set.union_subset_iff
definitional fact