(************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) (* Prop, ~ (forall n:U, P n) -> exists n : U, ~ P n. Proof (Classical_Pred_Type.not_all_ex_not U). Lemma not_all_not_ex : forall P:U -> Prop, ~ (forall n:U, ~ P n) -> exists n : U, P n. Proof (Classical_Pred_Type.not_all_not_ex U). Lemma not_ex_all_not : forall P:U -> Prop, ~ (exists n : U, P n) -> forall n:U, ~ P n. Proof (Classical_Pred_Type.not_ex_all_not U). Lemma not_ex_not_all : forall P:U -> Prop, ~ (exists n : U, ~ P n) -> forall n:U, P n. Proof (Classical_Pred_Type.not_ex_not_all U). Lemma ex_not_not_all : forall P:U -> Prop, (exists n : U, ~ P n) -> ~ (forall n:U, P n). Proof (Classical_Pred_Type.ex_not_not_all U). Lemma all_not_not_ex : forall P:U -> Prop, (forall n:U, ~ P n) -> ~ (exists n : U, P n). Proof (Classical_Pred_Type.all_not_not_ex U). End Generic.