theorem Set.singleton_subset_ifftheorem Set.singleton_subset_iff: ∀ {α : Type u} {a : α} {s : Set α}, {a} ⊆ s ↔ a ∈ s
Published by @sam · Jul 21, 2026
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zpg9xh52
Definitional, with no premises to accept.
Set.singleton_subset_iff
definitional fact