fact: Variable (M : fo_model Σ X) (x0 : X).
imports: List Arith Lia Undecidability.Shared.Libs.DLW.Utils(utils_tac) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.FOL.TRAKHTENBROT(notations utils fol_ops fo_sig fo_terms fo_logic)