NotNot : Rel ts -> Rel tsdoubleNegationElimination : Decidable n ts r => (witness : HVect ts) -> uncurry (NotNot r) witness -> uncurry r witnessdoubleNegationExists : Decidable n ts r => Ex ts (NotNot r) -> Ex ts rnegateDec : Dec a -> Dec (Not a)Convert a decision about a decidable property into one about its negation.
notExistsNotForall : {0 p : a -> Type} -> ((x : a) -> Dec (p x)) -> Dec (x : a ** Not (p x)) -> Dec ((x : a) -> p x)We can turn (Not (Exists Not)) into Forall for decidable types