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+Unset Strict Universe Declaration.
+
+Universe b.
+
+Universe c.
+
+Definition U : Type@{b} := Type@{c}.
+
+Module Type MT.
+
+Definition T := Prop.
+End MT.
+
+Module M : MT.
+   Definition T := Type@{b}.
+
+Print Universes.
+Fail End M.
+
+Set Universe Polymorphism.
+
+(* This is a modified version of Hurkens with all universes floating *)
+Section Hurkens.
+
+Variable down : Type -> Type.
+Variable up : Type -> Type.
+
+Hypothesis back : forall A, up (down A) -> A.
+
+Hypothesis forth : forall A, A -> up (down A).
+
+Hypothesis backforth : forall (A:Type) (P:A->Type) (a:A),
+      P (back A (forth A a)) -> P a.
+
+Hypothesis backforth_r : forall (A:Type) (P:A->Type) (a:A),
+      P a -> P (back A (forth A a)).
+
+(** Proof *)
+Definition V : Type := forall A:Type, ((up A -> Type) -> up A -> Type) -> up A -> Type.
+Definition U : Type := V -> Type.
+
+Definition sb (z:V) : V := fun A r a => r (z A r) a.
+Definition le (i:U -> Type) (x:U) : Type := x (fun A r a => i (fun v => sb v A r a)).
+Definition le' (i:up (down U) -> Type) (x:up (down U)) : Type := le (fun a:U => i (forth _ a)) (back _ x).
+Definition induct (i:U -> Type) : Type := forall x:U, up (le i x) -> up (i x).
+Definition WF : U := fun z => down (induct (fun a => z (down U) le' (forth _ a))).
+Definition I (x:U) : Type :=
+  (forall i:U -> Type, up (le i x) -> up (i (fun v => sb v (down U) le' (forth _ x)))) -> False.
+
+Lemma Omega : forall i:U -> Type, induct i -> up (i WF).
+Proof.
+intros i y.
+apply y.
+unfold le, WF, induct.
+apply forth.
+intros x H0.
+apply y.
+unfold sb, le', le.
+compute.
+apply backforth_r.
+exact H0.
+Qed.
+
+Lemma lemma1 : induct (fun u => down (I u)).
+Proof.
+unfold induct.
+intros x p.
+apply forth.
+intro q.
+generalize (q (fun u => down (I u)) p).
+intro r.
+apply back in r.
+apply r.
+intros i j.
+unfold le, sb, le', le in j |-.
+apply backforth in j.
+specialize q with (i := fun y => i (fun v:V => sb v (down U) le' (forth _ y))).
+apply q.
+exact j.
+Qed.
+
+Lemma lemma2 : (forall i:U -> Type, induct i -> up (i WF)) -> False.
+Proof.
+intro x.
+generalize (x (fun u => down (I u)) lemma1).
+intro r; apply back in r.
+apply r.
+intros i H0.
+apply (x (fun y => i (fun v => sb v (down U) le' (forth _ y)))).
+unfold le, WF in H0.
+apply back in H0.
+exact H0.
+Qed.
+
+Theorem paradox : False.
+Proof.
+exact (lemma2 Omega).
+Qed.
+
+End Hurkens.
+
+Polymorphic Record box (T : Type) := wrap {unwrap : T}.
+
+(* Here we instantiate to Set *)
+
+Fail Definition down (x : Type) : Prop := box x.
+Definition up (x : Prop) : Type := x.
+
+Fail Definition back A : up (down A) -> A := unwrap A.
+
+Fail Definition forth A : A -> up (down A) := wrap A.
+
+Definition id {A : Type} (a : A) := a.
+Definition setlt (A : Type@{i}) :=
+  let foo := Type@{i} : Type@{j} in True.
+
+Definition setle (B : Type@{i}) :=
+  let foo (A : Type@{j}) := A in foo B.
+
+Fail Check @setlt@{j Prop}.
+Check @setlt@{Prop j}.
+Check @setle@{Prop j}.
+
+Fail Definition foo := @setle@{j Prop}.
+Definition foo := @setle@{Prop j}.