fact: Definition M_is_bunion a b c := a ⊆ c /\ b ⊆ c /\ forall d, d ∈ c -> d ∈ a \/ d ∈ 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)