fact: Definition Markov : Prop := forall (P : nat -> Prop), (forall n:nat, {P n} + {~P n}) -> (~~exists n:nat, P n) -> exists n:nat, P n.
imports: Coq.QArith.QArith_base Coq.Reals.Abstract.ConstructiveReals Coq.Reals.Abstract.ConstructiveAbs