proposition: Lemma set_subset_bunion_guard s s' (S: s ⊆₁ s') ss ss' (EQ: ss = ss') : (⋃₁x ∈ s, ss x) ⊆₁ (⋃₁x ∈ s', ss' x).
proof: Proof. subst; u. Qed.
imports: HahnBase Program.Basics List Arith micromega.Lia Relations Setoid Morphisms