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