fact: Definition is_bunion a b c := a ⊆ c ∧ b ⊆ c ∧ ∀ $0 ∈ c`[↑] → $0 ∈ a`[↑] ∨ $0 ∈ b`[↑].
imports: Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.FST Undecidability.FOL.Sets.FST Lia Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation)