fact: Definition ax_HF2_true := ∀ ∀ t_f true $1 ≢ t_dum → t_f true $1 ≡ t_f true $0 → $1 ≡ $0.
imports: Lia Arith Undecidability.PCP.PCP Undecidability.PCP.Util.PCP_facts Undecidability.Synthetic.DecidabilityFacts Undecidability(FOL.Utils.FullSyntax) Undecidability(FOL.FSAT) Undecidability.Shared.ListAutomation