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theorem Set.mem_sUnion

theorem Set.mem_sUnion
: ∀ {α : Type u} {x : α} {S : Set (Set α)}, x ∈ ⋃₀ S ↔ ∃ t, t ∈ S ∧ x ∈ t

Published by @sam ·

View source in zpg9xh52

Definitional, with no premises to accept.