proposition: Theorem dblneg : forall A, (~~~A) -> ~A.
proof: Proof. intros A f a; apply f. intros g; apply g. exact a. Defined.
imports: HoTT(Basics Types HProp HSet Projective TruncType Truncations Modalities.Notnot Modalities.Open Modalities.Closed BoundedSearch Equiv.BiInv Spaces.Nat Spaces.Torus.TorusEquivCircles Metatheory.Core Metatheory.FunextVarieties)