(** The Drinker's paradox [[Smullyan78]] and its dual (a weak form of indefinite
    description, see e.g. in [[WarrenDienerMcKubreJordens18]])

[[Smullyan78]] What is the Name of this Book? Raymond Smullyan, 1978.

[[WarrenDienerMcKubreJordens18]] The Drinker Paradox and its Dual,
Louis Warren and Hannes Diener and Maarten McKubre-Jordens, 2018, unpublished.
*)

Definition DrinkerParadox A :=
  forall (P:A -> Prop),
    inhabited A -> exists x, P x -> forall y, P y.Definition DualDrinkerParadox A :=
  forall (P:A -> Prop),
    inhabited A -> exists x, (exists x, P x) -> P x.

(* Specifications: *)
Lemma independence_general_premises_dual_drinker A : IndependenceOfGeneralPremises A <-> DualDrinkerParadox A.